AU2003268593A1 - Doppler Ultrasound - Google Patents

Description

11/12 '03 THU 17:03 FAX 61 2 9888 7600 WATERMARK 006 P001 Seulan2(2 Rgulation 32(2)

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Doppler Ultrasound The following statement Is a full description of this invention, including the best method of performing it known to us: COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:03 FAX 61 2 9888 7600 WATERMARK [007 1 DOPPLER ULTRASOUND TECIUCAL FIELD The invention relates generally to medical monitoring and Sdiagnostic procedures and devices, and more particularly to a Doppler ultrsound method and apparatus afor monitoring blood flow.

BACKGROUND OF THE INVENTION Doppler ultrasound has been used to measure blood flow velocity for many years. The well-known Doppler shift pheomenon provides that ultrasonic signals reflected from moving targets will have a shift in frequency directly propordonal to the target velocity component parallel to the direction of the ubrasound beamn. The frequncy shift is the same for any object moving at a given velocity, whereas the amplitude of the detected signal is a fnmction of the acoustic reflictivity of the moving object reflecting the nltrasound. Pulcse Doppler ultrasound systenai commonly produce a spectrogram of the detected rctum signal frequency (Lea, velocity) as a function of time in a particular sample volume, with the spectrogram being used by a physician to determine blood flow shancterisSes of a patiknt.

Some Doppler ulIrasound systems also have the capability to detect and characterize emboli flowing in the bloodstream. An exampic Doppler ultrasound system with emnbolus detection capability is described in U.S. Patent No. 5,348,015, entitled "Method And Apparatus For Ultrasonically Detecting, Counting, and/or Characterizing Embolg, issued September 20, 1994, to Moehring et al, .tue disclosure of which is incorporated herein by rfrence.

Such ultrasound systems are advantageously used both for diagnostic exams (to detenrmine the presence and significance of vascular disease or dysfunction) and during smgical interventions (to indicate surgical manipulations that produce emboli or alterintenupt blood flow).

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:04 FAX 61 2 9888 7600 WATERMARK oo8 2 Typically, a user of ultrasound equipment finds it rather difficult to properly orient and position an ultrasound transducer or probe on the patient, as well as to select a depth along the ultrasound beam corresponding to the desired location where blood flow is to be monitored. This is particularly true in ultrasound applications such as transcranial Doppler imaging (TCD). The blood vessels most commonly observed with TCD are the middle, anterior, and posterior cerebral arteries, and the vertebral and basilar arteries. The Doppler transducer must be positioned so the ultrasound beam passes through the skull via the temporal windows for the cerebral arteries, and via the foramen magnum for the vertebral and basilar arteries. The user of the ultrasound equipment may find it difficult to locate these particular windows or to properly orient the ultrasound probe once the particular window is found.

A complicating factor in locating the ultrasound window Is determination of the proper depth at which the desired blood flow is located. Commonly, the user does not know if he Is looking in the correct direction at the wrong depth, the wrong direction at the right depth, or whether the ultrasound window is too poor for appreciating blood flow at all. Proper location and orientation of the Doppfer ultrasound probe, and the proper setting of depth parameters, is typically by trial and error. Not only does this make the use of Doppler ultrasound equipment quite inconvenient and difficult, it also creates a risk that the desired sample volume may not be properly located, with the corresponding diagnosis then being untenable or potentially improper.

SUMMARY OF THE INVENTION In a first aspect of the present invention, there is provided a Doppler ultrasound system for providing blood flow information of a subject, the system including: an ultrasound transducer from which ultrasound signals are emitted into the subject along an ultrasound beam axis: an ultrasound receiver detecting echo signals resulting from the ultrasound signals emitted into the subject; COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:04 FAX 61 2 9888 7600 WATERMARK 0009 3 an analog-to-digital converter (ADC) circuit coupled to the ultrasound receiver to quantize the echo signals received by the ultrasound receiver into digital sample values; a digital signal processor coupled to the ADC circuit for processing the digital sample values to calculate blood flow velocity data and detected Doppler signal power data as functions of time for a plurality of locations along the ultrasound beam axis; a graphical display; and a display controller coupled to the digital signal processor and the graphical display for controlling the graphical display to display blood flow velocity data and detected Doppler signal power data as a graphical image representative of blood flow detected along the ultrasound beam axis as a function of time. the graphical image having a color at each of the locations along the ultrasound beam axis for which data is displayed based on the blood flow velocity data and the color having a color property that varies based on the detected Doppler signal power data.

In a second aspect of the present invention, there is provided a data processing engine for a Doppler ultrasound system having an ultrasound transducer from which. ultrasound signals are emitted into the subject along an ultrasound beam axis, an ultrasound receiver detecting echo signals resulting from the ultrasound signals emitted into the subject, and a color graphical display, the data processing engine including: an analog-to-digital converter (ADC) circuit coupled to the ultrasound receiver to quantize the echo signals received by the ultrasound receiver into digital sample values, the digital sample values stored as sample vectors; a digital signal processor coupled to the ADC circuit for processing the digital sample vectors to calculate blood flow data and detected Doppler signal power data as functions of time for a plurality of locations along the ultrasound beam axis; and a display controller coupled to the digital signal processor and the graphical display for controlling the graphical display to display the blood flow data and the detected Doppler signal power data as a graphical image representative of the blood flow detected along the ultrasound beam axis as a COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUIL 17:04 FAX 61 2 9888 7600 WATERMARK 010o 3a function of time, the graphical image having a color at each of the locations for which data is displayed based on the blood flow data and the color having a color property that varies based on the detected Doppler signal power data.

In a third aspect of the present invention, there is provided a method for providing blood flow information of a subject to which the Doppler ultrasound system emitting pulsed ultrasound signals along an ultrasound beam axis and detecting echo signals resulting therefrom, is applied, the method including the steps of: for each pulse of ultrasound, quantizing the detected echo signals to generate a plurality of digital sample values representative of the echo signals; processing digital sample values of the pulses of ultrasound to calculate data representative of blood flow Information as a function of time including detected Doppler signal power data for a plurality of locations along the ultrasound beam axis; and displaying the data representative of the blood flow information for the plurality of locations along the ultrasound beam axis as a function of time. the blood flow information displayed as having an associated color at each of the plurality of locations, the associated color having a color property that varies based on the detected Doppler signal power data.

In a fourth aspect of the present invention, there is provided a method for providing blood flow information of a subject to which a Doppler ultrasound system emitting ultrasound signals along an ultrasound beam axis and detecting echo signals resulting therefrom is applied, the method including the steps of: quantizing the detected echo signals to generate a plurality of digital sample values representative of the echo signals; generating quadrature vectors from the plurality of digital sample values; processing the quadrature vectors to calculate blood flow data and detected Doppler signal power data as functions of time for a plurality of locations along the ultrasound beam axis; and displaying the blood flow data and the detected Doppler signal power data as a graphical Image representative of blood flow detected along the ultrasound beam axis as a function of time, the detected blood flow displayed as having a color at each of the locations for which data is displayed based on the blood flow COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:05 FAX 61 2 9888 7600 WATERMARK EIOII 3b data and the color having a color property based on the detected Doppler signal power data.

In fifth aspect of the present invention, there is provided a computerreadable medium having computer executable instructions for controlling digital processing circuitry in a Doppler ultrasound system to process detected ultrasound echo signals and provide blood flow Information. by: controlling an analog-to-digital converter (ADC) circuit to quantize the detected ultrasound echo signals to generate a plurality of digital sample values representative of the ultrasound echo signal; generating quadrature vectors from the plurality of digital sample values; processing the quadrature vectors to calculate blood flow data as a function of time including detected Doppler signal power data for a plurality of locations along the ultrasound beam axis; and processing the blood flow data for display as a function of time for the plurality of locations along the ultrasound beam axis, the blood flow data displayed as having an associated color at each of the plurality of locations indicative of blood flow velocity and the associated color having a color property based on the detected Doppler signal power data.

In a sixth aspect of the present invention, there is provided a Doppler ultrasound system for processing ultrasound signals along an ultrasound- beam axis and for displaying information to a user concerning blood flow, including: an ultrasound transducer operable to detect ultrasound signals and responsively produce corresponding electrical signals; a graphical display device; and signal processing circuitry coupled to the transducer and operable to receive the electric signals and determine blood flow characteristics corresponding with the detected ultrasound signals, the signal processing circuitry further coupled to the graphical display device and operable to process the detected ultrasound signals and provide data to the graphical display to display blood flow information along a time domain for a plurality of locations along the ultrasound beam axis a depiction of detected blood flow having intensity varying as a function of detected Doppler ultrasound amplitude.

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:05 FAX 61 2 9888 7600 WATERMARK M012 3c In a seventh aspect of the present invention, there is provided a method in a Doppler ultrasound system for providing information to a user concerning blood flow, including the steps of: displaying blood flow information as a function of time for a plurality of locations along an ultrasound beam axis at which blood flow is detected; and varying display intensity as a function of detected Doppler ultrasound amplitude and detected blood flow velocity at each of the locations.

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:05 FAX 61 2 9888 7600 WATERMARK [013 4 BRIEF DESCRIPTION OF THE DRAWINGS Figure I is a graphical diagram.depicting a first Doppler ultrasound system display mode in accordance with an embodiment of the invention.

Figure 2 is a graphical diagram depicting velocity and signal power parameters used in preparation of the display mode of Figure 1.

Figure 3 is a graphical diagram depicting velocity and signal power parameters used in preparation of a altenative embodiment of the display mode of Figure 1.

Figure 4 shows the alternative embodiment of the display mode of Figur I in color.

Figure 5 is a graphical diagram depicting the display mode of Figure 4 and its use to identify the pulnonary artery, Figure 6 is a graphical diagram depicting a second Doppler ultrasound system display mode in accordance with an embodiment of the invention.

Figure 7 shows two views of the display mode of Figure 6 in color.

Figre 8 is the graphical diagram of the display mode shown in Figure 1, further depicting and distinguishing embolic signals from artifact signals.

Figre 9 is a functional block diagram depicting a Doppler ultrasond system in accordance with an embodiment of the invention.

Figures 10 and II are fhnctional block diagrams depicting particular details of pulse Doppler signal processing circuitry included in the Doppler ultrasound system of Figure 9.

Figures 12-16 are process flow charts depicting particular operations performed by the pulse Doppler signal processing circuity of Figures and 11.

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:05 FAX 61 2 9888 7600 WATERMARK 2014 DETAILED DESCRIPTION OF THE INVENTION -The following describes a novel method and apparatus for providing Doppler ltrasound information to a user, such as in connection with measuring blood velocities to detect hemodynamically significant deviations from normal values, and to assess blood flow for the occurrence of microembolic signals. Certain details are set forth to provide a sufficient understanding of the invention. However, it will be clear to one skilled in the art that the invention may be practiced without these particular dtails. In other instances, well-known circuits, control signals, timing protocols, and software operations have not been shown in detail in order to avoid unnecessarily obscuring the invention.

Figure I is a graphical diagram depicting a first display mode of Doppler ultrasound information in accordance with an embodiment of the invention In this first display mode, referred to as an Aiming mode 100, two distinct ultrasound displays are provided to the user. A depth-mode display 102 depicts, with color, blood flow away from and towards the ultrasound probe at various depths along the ultrasound beam axis (vertical axis) as a function of time (horizontal axis).

The depth-mode display.102 includes colored regions 104 and 106.

9 Region 104 is generally colored red and depicts blood flow having a velocity component directed towards the probe and in a specific depth range. Region ]06 is generally colored blue and depicts blood flow having a velocity component away from the probe and in a specific depth range. The red and blue regions are not of uniform Color, with the intensity of red varying as a function of the detected intensity of the return Doppler ultrasound signal. Those skilled in the art will understand that such a display is similar to the conventional color Mmode display, in which variation in red and blue coloration is associated with variation in detected blood flow velocities. However, such M-mode displays have not been used concurrently with a spectrogram and with the specific application of locating blood flow as an input to the spectrogram, from which diagnostic decisions are made.

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:06 FAX 61 2 9888 7600 WATERMARK o015 'U99/26740 6 The Aiming mode 100 also includes a displayed spectrogram 108, with Figure 1 depicting a velocity envelope showing the characteristic systolicdiastolic pattern. Like the depth-mode display 102, the spectrogram 108 includes data points (not shown) within the velocity envelope that are colored in varying intensity as a function of the detected intensity of the retmr ultrasound signal.

The particular sample volume for which the spectrogram 108 applies is at a depth indicated in the depth-mode display 102 by a depth indicator or pointer 109. In this way, a user of the ultrasound system can conveniently see and select particular depths at which to measure the spectrogram 108. The depth-mode display 102 readily and conveniently provides the information concerning the range of appropriate depths at which a meaningful spectrogram may be obtained.

As described above, the color intensity of regions 104 and 106 preferably vary as a fnction of the detected intensity of the return ultrasound signal. Referring to Figure 2, a graphical diagram depicts how such color intensity is determined. In order to avoid display of spurious information, signals that may be intense but low velocity (such as due to tissue motion) are ignored and not displayed in the depth-mode display 102 of Figure 1. This is referred to as clutter filtering and is depicted in Figure 2 as the threshold magnitude clutter cutoff limits for positive and negative velocities. Similarly, low power signals associated with noise are also ignored and not displayed in the depth-mode display 102 of Figure 1. The user can determine the upper power limit for the color intensity mapping by selecting a power range value. Signals above a maximum power are then ignored-another clutter filtering which is especially helpful when monitoring blood flow in the cardiac environment. Those skilled in the art will appreciate that other filtering techniques may be employed to improve the depth-mode display image, including delta modulator or other suitably adapted filtering techniques.

While the currently preferred embodiment of the depth-mode display 102 employs color intensity mapping as a function of signal intensity, and further colored red or blue according to flow directions towards or away COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:06 FAX 81 2 9888 7600 WATERMARK 0016 7 from the probe, those skilled in the art will appreciate that color intensity as a function of detected velocity may be employed instead. In such case, and as shown in Figure 3, color intensity varies frm the clutter cutoff magnitude to a maximum velocity magnitude, corresponding with one-half the pulse repetition frequency (PRF). Detected signals,having a power below the noise threshold or above the selected upper power limit are ignored. Figure 4 is a color figure that shows the Aiming mode display 100 in which the color intensity of the regions 104 and 106 vary as a function of detected velocity. Both the depth-mode display 102 and the specrogram 108 are displayed relative to the same time axis, and the depth-mode display shows variation both in spatial extent and in color intensity with the same periodicity as the heart beat Those skilled in the art will also appreciate that instead of varying color intensity solely as a function of signal amplitude or solely as a function of velocity, one could advantageously vary color intensity as a function of both signal amplitude and velocity.

The particularly depicted depth-mode display 102 shown in Figure I shows a simplified display ofa single, well-defined red region 104 and a single, well-defined blue region 106. Those skilled in the art will appreciate that the number and characteristics of colored regions will vary depending on ultrasound probe placement and orientation. Indeed, a catalogue of characteristic depth-mode displays can be provided to assist the user in determining whether a particularly desired blood vessel has, in fact, been located. Once the user finds the characteristic depth-mode display for the desired blood vessel, the user can then conveniently determine the depth at which to measure the spectrogram 108, The Aiming mode 100 enables the user to quickly position the ulrasound probe, such as adjacent to an ultrasound window through the skull so that intracranial blood flow can be detected. Use of colorized representation of signal amplitude is particularly advantageous for this purpose, since a strong signal is indicative of good probe location and orientation. The use of colorized representation of flow velocity may not be as advantageous, except where blood flow velocities vary significantly over blood vessel cross-section. However, COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:06 FAX 61 2 9888 7600 WATERMARK [a1017 8 when attempting to monitor blood flow near appreciably moving tissue cardiac motion above clutter cutoff velocity), colorized representation of flow velocities may be preferred.

Referring to igure 5, use of the Aiming mode 100 is shown in connection with identifying a particular blood vessel, such as the pulmonary artery or femoral vein. In this case, a colorized representation of flow velocity is advantageously used in the depth-mode display 102, because of the high variation in blood flow velocities in these particular blood vessels. By observing the temporal variation in the depth-mode display 102, and the corresponding spectrogram 108, a user can identify optimal location of the pulmonary artery as follows: the depth-mode display of the pulmonay artery will be blue with the same periodicity as the heart beat; (2)the blue region will typically reside between 4 and 9 cm depth; along the time axis, the blue signal will be relatively intense in the middle of systole, corresponding to peak velocity: and the signal will have the largest vertical extent in the depth-mode display, indicating that the user has positioned the probe such that the longest section of the pulmonary artery is aligned coincident with the ultrasound beam during systole. The user can then adjust other parameters, such as gate depth for the displayed spectrogram 108 and clutter filter parameters.

The Aiming mode 100 also indicates to the user where to set the depth of the pulse Doppler sample gate so that the spectrogram 108 wil process Doppler shifts from desired blood flow signals. It is the spectrogram 108 that is of primary clinical interest, allowing the user to observe and measure parameters associated with a particular blood flow and providing information that might suggest hemodynamically significant deviations in that blood flow. Along with the depth-mode display 102 and the correspondingly selected spectrogram 108, the information displayed to a user also typically includes well-known numerical parameters associated with the spectrogram, such as mean peak systolic velocity, mean end diastolic velocity, pulsatility index, and the relative change in mean peak systolic velocity over time. Those skilled in the art will appreciate that COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:07 FAX 61 2 9888 7600 WATERMARK 0os18 9 other parameters and displays may also be provided, including data provided by other monitoring devices, such as EKG- or EEG-related information.

The Aiming mode display 100 of Figure 1 is particularly useful in positioning and orienting the Doppler ultrasound probe, and in first selecting a depth at which to measure the spectrogram 108. Following probe location and orientation and range gate selection, the user will typically prefer to have an information display emphasizing the clinically valuable spectrogram 108.

O Referring to Figure 6, a second display mode is shown that is referred to as a Spectral mode 110. In this mode, the spectrogram 108 occupies a larger display area, Instead of the full depth-mode display 102, a compressed depth-mode display 112 is provided. This compressed depth-mode display 112, on a shortened time scale, provides information concerning the depth of the sample volume at which the specroram 108 is taken, and the status ofthe blood flow in that sample volume, towards or away from the probe Thus, the user is continually informed concerning the desired sample volume depth and associated blood flow. This allows for quick understanding and compensation for any changes in the location of the desired sample volume relative to the blood flow, such as due to probe motion. This also allows a user of the ultrasound system to fine tune the sample volume depth even while focusing primary attention on the clinically important spectrogram 108.

Figure 7 shows two different views of the Spectral mode 110 in color. In one view, the selected depth indicated by the pointer 109 in the compressed depth.mode display 112 is not a location at which blood flows, and consequently no there are no blood flow signals in the displayed spectrogram 108. In the other view, the selected depth indicated by the pointer 109 does coincide with blood flow, and a corresponding spectrogram 108 is displayed. In the particular embodiment shown in Figure 7, the color intensity of the region 104 varies as a function of detected velocity, and shows a characteristic color variation that may be associated with variation in blood velocity across blood COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:07 FAX 61 2 9888 7600 WATERMARK 1019 vessel cross-section, a variation with depth in the alignment of the detected blood flow relative to the ultrasound beam axis, or both.

Those skilled in the art will appreciate the important advantages provided by the diagnostic information displays shown in Figures 1,4, 6, and 7.

While the displayed spectrogram 108 is not itself new, today's pulse Doppler ultrasound systems that do not have B-mode capability lack a means for successfully and reliably locating and orienting an ultrasound probe and detennining an appropriate sample volume depth at which to detect the blood flow of interest Also, while colorized representation of blood flow directions and speeds or signal amplitude is well known in the ar such as in color M-mode displays, such displays have not been used for the purpose of aiming ultrasound probes or in selecting particular sample volume depths for conourent spectrogram analysis.

Referring to Figure 8, the simultaneous presentation of the depthmode display 102 and spectrogram 10 can also provide important information for detecting embolic signals and differentiating such signals from non-embolic artifacts. Figure 8 depicts three events: A, B, and C. In event A, the depthmode display 102 shows a particularly high intensity signal having a non-vertical slope-i.., a high-intensity signal that occurs at different depths at different times. In event A, the signal exists only within the boundary of one of the colored blood flow regions 104 and 106. In the spectrogram 108, a particularly high intensity signal is seen to have different velocities, bounded by the maximum flow velocity, within a short temporal region within the heartbeat cycle. Event A is stong evidence of an embolus passing through a blood flow region near the selected sample volume.

Event B is another likely candidate for an embolus. In this case, the high-intensity signal seen in the depth-mode display 102 is non-vertical, but does not appear exclusively within a range of depths where blood is flowing, While this signal is strong enough and/or has a long enough back scatter to appear outside the blood flow margin in the depth-mode display 102, the COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:07 FAX 61 2 9888 7600 WATERMARK [020 11 spectrogram display 108 still shows the characteristic high intensity transient signal associated with an embolus. Event B is also evidence of an embolus, but likely an embolus different in nature from that associated with event A.

Although the particular signal characteristics of various emboli have not yet been fully explored in the depth-mode display, the distinction between events A and B is likely that of different embolus types. For example, event A may be associated with a particulate embohls, whereas event B may be associated with a gaseous embolus, with the different acoustic properties of a gas bubble causing the particularly long back scatter signal and the appearance of occurrence outside the demonstrated blood flow margins.

Event C is an artifat, whether associated with probe motion or some other non-embolic event. Event C appears as a vertical line in the depthmode display 102, meaning that a high-intensity signal was detected at all depth locations at precisely the same time-a characteristic associated with probe motion or other artifact. Similarly, the high-intensity signal displayed in the spectrogram display 108 is a vertical line indicating a high-intensity signal detected for a wide range of velocities (including both positive and negative velocities and velocities in excess of the maximum blood flow velocities) at precisely the same time. Event C then is readily characterized as an artifact signal, and not embolic in nature.

Those skilled in the art will appreciate that the simultaneous display of the depth-mode display 102 and the spectrogram 108 provides not only convenient means for locating the desired sample volume, but also provides a particularly useful technique for distinguishing embolic signals from artifact signals, and perhaps even for characterizing different embolic signals. Such embolic detection and characterization is easily observed by the operator, but can also be automatically performed and recorded by the ultrasound apparatus.

Automatic embolus detection is provided by observing activity in two or more sample gates within the blood flow at the same time. The system discriminates between two different detection hypotheses: COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUIT 17:08 FAX 61 2 9888 7600 WATERMARK (1021 12 If the signal is embolic, then it will present itself in multiple sample gates over a succession of different times.

If the signal is a probe motion artifact, then it will present itself in multiple sample gates simultaneously.

These two hypotheses are mutually exclusive, and events that are declared embolic arc done so after passing the "Basic Identification Criteria of Doppler Microembolic Signals" (see, for example. Stroke, vol. 26, p. 1123, 1995) and verifying that successive detection (by time-series analysis or other suitable technique) of the embolic signal in different sample gates is done at different points in time, and that the time delay is consistent with the direction of blood flow. The differentiation of embolic from artifact signals can be further confirmed by also observing activity at one or more sample gates. outside the blood flow.

Figure 9 is a functional block diagram that depicts an ultrasound system 150 in accordance with an embodiment of the invention. The ultrasound system 150 produces the various display modes described above in connection with Figures 1-8 on an integrated flat panel display 152 or other desired display format via a display interface connector 154. The signal processing core of the Doppler ultrasound system 150 is a master pulse Doppler circuit 156 and a slave pulse Doppler circuit 158. The Doppler probes 160 are coupled with other system components by a probe switching circuit 162. The probe switching circuit 162 provides both presence-detect functionality and the ability to distinguish between various probes, such as by detecting encoding resistors used in probe cables or by other conventional probe-type detection. By providing both the master and slave pulse Doppler circuits 156 and 158, two separate ultrasound probes 160 may be employed, thereby providing unilateral or bilateral ultrasound sensing capability (such as bilateral transcranial measurement of blood velocity in the basal arteries of the brain). The master and slave pulse COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:08 FAX 61 2 9888 7600 WATERMARK 1022 13 Doppler circuits 156 and 158 receive the ultrasound signals detected by the respective probes 160 and perform signal and data processing operations, as will be described in detail below. Data is then transmitted to a general purpose host computer 164 that provides data storage and display. A suitable host computer 164 is a 200 MHz Pentium processor-based system having display, keyboard, internal hard disk, and external storage controllers, although any of a variety of suitably adapted computer systems may be employed.

The ultrasound system 150 also provides Doppler audio output signals via audio speakers 166, as well as via audio lines 168 for storage or for oniput via an alternative mdium. The ultrasound system 150 also includes a microphone 170 for receipt of audible information input by the user. This information can then be output for external storage or playback via a voice line 172. The user interfaces with the ultrasound system 150 primarily via a keyboard or other remote input control unit 174 coupled with the host computer 164.

Figures 10 and 11 depict particular details of the master and slave pulse Doppler circuits 156 and 158. To the extent Figures 10 and 11 depict similar circuit saucttres and interconnections, these will be described once with identical reference numbers used in both Figures. Figure 10 also depicts details concerning the input and output of audio information to and from the ultrasound system 150 via the microphone 170, the speakers 166, and the audio output lines 168 172, the operations of which are controlled by the master pulse Doppler circuit 156.

At the transducer input/output stage, each of the pulse Doppler circuits 156 and 158 includes a transmit/receive switch circuit 175 operating under control of a timing and control circuit 176 (with the particular timing of operations being controlled by the timing and control circuit 176 of the master pulse Doppler circuit 156). The timing and control circuit 176 also controls operation of a tansmit circuit 178 that provides the output drive signal causing the Doppler probes 160 (see Figure 9) to emit ultrasound. The timing and COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:08 FAX 61 2 9888 7600 WATERMARK 14 control circuit 176 also controls an analogto-digital converter circuit 180 coupled to the transmit/receive switch 175 by a receiver circuit 182_ The fnmction and operation of circuits 175-182 are well known to those skilled in the art and need not be described fbrther.

The primary signal processing functions of the pulse Doppler circuits 156 and 158 are performed by four digital signal processors P1-P4. PI is at the front end and receives digitizd transducer data from the receiver 182 via the analog-to-digital converter circuit 180 and a data buffer circuit or FIFO 186.

P4 is at the back end and peforms higher level tasks such as final display preparation. A suitable digital signal processor for PI is a Texas Instruments TMS320LC549 integer processor, and suitable digital signal processors for P2- P4 are Texas Instruments TMS320C31 floating point processors, although other digital signal processing circuits may be employed to perform substantially the same functions in accordance with the invention.

Received ultrasound signals are first processed by the digital signal processor PI and then passed through the signal processing pipeline of the digital signal processors P2, P, and P4. As described in detail below, the digital signal processor PI constructs quadrature vectors from the received digital data, performs filtering operations, and outputs Doppler shift signals associated with 64 different range gate positions. The digital signal processor P2 performs cluer cancellation at all gate depths. The digital signal processor P3 performs a variety of calculations, including autocorrelation, phase, and power calculations.

P3 also provides preparation of the quadrature data for stereo audio output. The digital signal processor P4 performs most of the calculations associated with the spectrogram display, including computation of the spectrogram envelope, systole detection, and also prepares final calculations associated with preparation of the Aiming display.

Each of the digital signal processors PI-P4 is coupled with the host computer 164 (see Figure 9) via a host bus 187 and control data buffer circuitry, such as corresponding FFOs 188(1) 188(4). This buffer circuitry allows COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:09 FAX 61 2 9888 7600 WATERMARK (0024 initialization and program loading of the digital signal processors PI-P4, as well as other operational communications between the digital signal processors PI-P4 and the host computer. Each of the digital signal processors P2-P4 is coupled with an associated high-speed memory or SRAM 190(2) 190(4), which function as program and data memories for the associated signal processors. In the particularly depicted signal processing chain of Figure 10 or 11, the digital signal processor PI has sufficient internal memoy, and no external program and data memory need be provided. Transmission of data from one digital signal processor to the next is provided by intervening data buffer or FIFO circuitry 192(2) 192(4). The ultrasound data processed by the digital signal processor P4 is provided to the host computer 164 via data buffer circuitry such as a dual port SRAM 194.

Referring to Figure 10, the digital signal processor P4 of the master pulse Doppler circuit 156 also processes audio input via the microphone 170, as well as controlling provision of the audio output signals to the speakers 166 and audio output lines 168, 172. P4 controls the audio output signals by controlling oprations of an audio control circuit 196, which receives audio signals from both the master and the slave pulse Doppler circuits 156 and 158.

Referring to process flow charts shown in Figures 12-16, a detailed description will now be provided of the operations performed by of each of the digital signal processors P1-P4 included in both the master and slave pulse Doppler circuits 156 and 158. Particular detailed calculations and numerical information are provided to disclose a current embodiment of the invention, but those skilled in the art will appreciate that these details arc exemplary and need not be included in other embodiments of the invention.

Referring to Figure 12, the operations of digital signal processor PI are as follows: 1. DIGITIZATION OF RAW DATA. Read a series of N 14-bit values from the input A/D. The values are converted at 4X the Doppler COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:09 FAX 61 2 9888 7600 WATERMARK Z025 16 carrier frequency (8MHz), and commence synchronously with the start of the trsmit burst N=1000 if the Doppler pulse repetition frequency (PRF) is SkHz 1280 if the Doppler PRF is 625Hz and 1600 if the Doppler PRF i SkHz.

2. QUADRATURE VECTOR CONSTRUCTION. Construct two vectors with N/4 points each according to the following rules: and Bi(1 N/4A(2:4.N;I-2).(4.4N).

Br and Bi are the digitally demodulated quadrature Doppler values for a series of N/4 different gate depths. The subtractions here remove DC bias from the data.

3. LOW-PASS FILTER COEFICIENTS. Br and Bi contain frequencies up.

to carrier/4, and need to be fimther filtered to remove noise outside the bandwidth of the Doppler transmit burst The coeicients for accomplishing this low-pass filtering are determined by a creating, with standard digital filter design softwvare such as MATLAB, an order 21 lowpass FIR filter. The normalized cutoff of this filter is where T is the time duration of the transmit burst and fs is the sample rate of the data in Br and Bi (2MIz). Call this filter C(1:21). The coefficients of this filter will vary as the transmit burst length is changed by the user, and a bank of several different sets of filter coefficients is accordingly stored to memory.

4. INDEX ARRAYS. Data from 64 range gate positions re to be pmrocessed and passed onto P2. For ease of graphical display, these range gate positions are selected to be Imm apart. However, the quadrature vectors Br and Bi do not contain elements that arc spaced Imm apart-they are .385mm apart Therefore, indices into the Br and Bi arrays are used that correspond to values falling closest to multiples of Imm, as a means to decimating Br and Bi to umm sampling increments. This is done by having a prestored array of indices, DI(J:64), corresponding to depths COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:09 FAX 61 2 9888 7600 WATERMARK IM026 17 29:92m for 8kHz PRF, and indices D2(1:64) and D3(1:64) with corresponding or deeper depth ranges for 625kHz and 5kHz PRFs.

LOW-PASS FILTER AND DECIMAnON OF QUADRATURE

DATA.

The Br and Bi arrays are low-pass filtered and decimated to 64 gates by S the following rules (note cb> is the 32 bit accumulated integer dot product of vectors a and b): SkHz PRF: ErGi) C, B(DI(j+(-io0;Ilo))> Ei) C, andj-1:64.

6.25kHzPRF: Er c C, EiJ)* C, and j=-1:64.

PRF:

Er)= C, Br(D3j)+(-10:10))> EiO) C, andj=1:64.

6. PASS RESULTS TO P2. Er and Ei, 128 values altogether, comprise the Doppler shift data for 1 pulse repetition period, over a set of 64 different sample gates spaced approximately 1mm apart. These arrays are passed to P2 with each new transmtnit burst.

Refening to Figure 13, the operations of digital signal processor P2 are as follows: 1. ACCUMULATE INPUT DATA. Collect a buffer of M Er and Ei vectors from PI over a period of 8m, into floating point matrices Fr and FiL At the PRFs of [8,6.25,S]kHz, the matrices Fr and Fi will each contain respectively M[64,50.40] vectors. The jthi Er and Ei vectors at their respective destinations are denoted by Fr(l:64j) and Fi(1:64J) (these are column vectors). The kth gate depth across the M collected vectors is indexed by Fr(kM) and Fi(k:M) (these are row vectors).

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:10 FAX 61 2 9888 7600 WATERMARK 027 18 2. PRESERVATION OF RAW DATA AT "CHOSEN" GATE DEPTH.

Reserve in separate buffer the raw data at the user-chosen gate depth, t at which the Doppler spectrogram is proccssed. This row vector data, G1(LMM)Fr(xo,1M) and Gi(1M)=Fi(kl:M), is passed forward to P3 and eventually to the host for recording purposes.

3. CLUTTER CANCELLATION. Apply a fourth order clutter cancellation filter to each row of Fr and Fi. Hr(I:64,:M) and Hi(1:64,1M) are the destination matrices of the Sitered Fr(l:64,1:M) and Fi(:64,1M) data.

Application of this filter with continuity reqties maintaining state variables and some previous Fr and Fi values. The coefficients of the clutter filter will vay depending on the user choice of [Low Boost, 200Hz 300Hz, and High Boost]. These coefficients are available.

by table lookup in processor RAM, given the user choice from the above options.

4. PASS RESULTS TO P3.

Or, Gi, Hr and HI are passed to P3 for further processing.

Referring to Figure 14, the operations of digital signal processor P3 are as follows: 1. ACCUMULATE INPUT DATA. Receive Or, G, Hr and Hi from P2.

2. COMPUTE AUTOCORRELAION. Comrpute the first lag of the autocorrelation of the data at each gate over time. Use Pll M values at each gate in this calculation. This will generate an array of 64 complex values, one for each gate. For the kth gate depth, let Then the first lag autocorrelation for this depth is AC(k) (Note that in a dot product of complex values, the second vector is conjugated. Also note that this and all dot products in P2, P3, or P4 are floating point calculations.) In this manner, construct the complex vector AC(l:64).

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:10 FAX 61 2 9888 7600 WATERMARK 1028 19 3. COMPUTE PHASE FOR EACH AC VALUE. For each autocorrelation value, us a four quadrant arctangent lookup to determine the phase of the complex value. Specifically, ANGLE(k) arctan( imag( AC(k) real(AC(k))). The ANGLE(k) value is proportional to the mean flow velocty at the gate depth k.

4. If cmbolus characterization distinguishing a particle from a bubble) capability is enabled, the method routes to a subroutine described below in connection with Figure 16.

COMPUTE POWER. Compute the signal power. Use all M values at each gate in this calclation. This will generate an aay of 64 real values, one for each gate. For the kth gate depth, again let P=Hr(k,L:M)+J Then the power for this depth is POWER(k) (note that in a dot product of complex values, the second vector is conjugated). In this manner, construct the real vector POWER(1:64).

6. LOG COMPRESS POWER. Convert POWER to Decibels: POWERd(1:64) 10*Iog0(POWER(I:64)).

7. COMPUTE POWER TRACES FOR EMBOLUS DETECTION. For each of four preset gate depths (one being the user selected depth and the other three being correspondingly calculated), compute power from a 60 point moving window at M different positions of the window. Note that some history of the data at the specific gate depths will be required to maintain this calculation without interrption from new data spilling in every 8ms.

Specifically, for gate n, POWER_TRACEn(i) <Hr(n,i-59:i) jHi(n,i- 59:) Hr(n,i-59i) +jHi(ni-59:i). Note 3 power traces are taken from the region including the sample volume placed inside blood fow, while the fourth power trace is taken from a sample volume well outside the blood flow.

8. COMPLEX BANDPASS FILTER FOR USE IN AUDIO OUTPUT PREPARATION. The min and max frequencies resulting from user COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THLT 17:10 FAX 81 2 9888 7600 WATERMARK M029 specified spectral nwrapping of the spectrogram are used to determine a complex bandpass filter for making the audio output sound congment with what is shown on the spewogram display. For example, if the unwrapping occurs at [-1,7kH, then the audio complex bandpass fither S has edges at -1kHz and +7kHz A bank of several sets of complex bandpass fier coefficients, corresponding to different unwrap ranges, is generated ofine and placed in memnory. Each coefficient set corresponds to one of the unwrapping selections the user can make. Let the operative set of filter coefficients be called UWa(I;O) and UWb(l:OX where 0 is the filter order plus aone.

9. AUDIO OUTPUT PREPARATION: RESAMPLE. At the gate depth selected by the user, k, the Doppler shift signals are to be played out the audio speakers. Before doing so, sama prepping of the audio signals is important to match the user-selected spectral iwrapping. Resample the audio signal r(k,3:M) and Hi(k1:M) to twice the ?f by multiplexing the respective arrays with zeros: Qr(k,1:2M){Hr(,1J) 0, Hr(k,2), Hr(k,3, 0, Hr(kM), 0) and Qi(k,12M){Hi(kI), 0, Hi(k,2), 0, if3l) 0, Hi(kM4 0).

AUDIO OUTPUT PREPARATION: COMPLEX BANDPASS. Apply a complex bandpass filter to Qzi+jQi in order to remove the extra images introduced by muhiplexiig the data with zeros: where Q(k) Qr(k)4jQi(k).

11. AUDIO OUTPUT PREPARATION: HILBERT TRANSFORM. The audio data in the sequence R(n) is in quadrature format and needs to be converted into stereo left and right for playing to the operator. This is done with a Hilbert transform, and a 95 point transform, H(1:95), is used in this work-the coefficients can be obtained with fonmulas in the literature or standard signal processing software such as MATLAB. The COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:10 FAX 61 2 9888 7600 WATERMARK 0030 21 application of the Hilbert trasform to a data sequence is done as an FIR mter. Construction of stereo separated signals RL and RR from Rn) is done according to [RL Hilbert(Rr) Delay RR Hilbert(Rr)- Delay(Ri)] where Delay is a (Nh+4-l)/2 step delay of the imaginary component of R. and Nh is the size of the Hilbert filter 12. Pass Gr, Gi ANGLE, POWERd, POWER_TRACE POWER

TRACE

POWERflAG3, POWERTRACE4. Rr, R RL and RR to P4 for further proccssing.

Refeing to Figr 15, the operations of digital signal processor P4 are as follows: 1. ACCUMULATE INPUT DATA. Receive Gr. i, ANGLE, POWERd, POWER TRACE!L POWER TRACE2 POWER_TRACE3, POWER TRACE4, Rr, Ri, RL and RR from P3.

2. CALCULATE SPECTROGRAM. Compute power spectrum via the following steps: a) Concatenate new points in the Ri+jRi sequence with old points such that there are 128 points altogether, b) Multiply the 128 point sequence against a 128 point Hanning window, c) Calculate P, the FFT of the 128 point sequence, d) Calculate Pd JO*logIO(P), and e) FFrTSHIFT th Pd sequence such that DC is at its center.

3. ENVELOPE. Compute the maximum frequency follower or "envelope" function, which indicates the upper edge of the flow signals in the spectrogram. This is an integer between 0 and 63, and is indexed by FFT caculatiodn-Le, for every spectral line calculation there is one value of E. Those skilled in the art will know of a variety of algorithms for making this calculation.

4. SYSTOLE DETECTION. Based on the maximum frequency follower, detect the start of systole. When the systolic start has been determined, set SYSTOLE_FLAG-TRUE. Also calculate the end diastolic velocity COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUJ 17:11 FAX 61 2 9888 7600WAEAR J03

WATERMARK

Ch 0.31 value,6 VEND, the peak systolic velocity value, VPEAJ, and the mcan velocity, V.MEAN.

AI MG DISPLAY PREPARATION. hPrear the Aiming dislay via the following steps: a) Subtract the value of the -ai, noise"- Parameter set bythe user from the POWEmd W~2PW~d.i nieb multply POWERdZ by a factor which is 64 (the number of color shades) divided by the value of the range parameter Set by the user- POW7E3=PW~d.

6 4 im_ nmc,) clip the resulting power data at Oon th low end and 63ontehigh gwsno c.pudt entries in a 6 4-valuc red or blue Color table, And place results in arry POWERd4, and d) multiply each of the power values by 1. 0 or-1 depending respectvely on whether the associated ANGLE value is greate than the "filer c'utoff ,paramctet,% less in absolute value tha the filter cutoff parameter, or less than the negative of the fiter Cutoff parameter.

This results in 64 values (one per gate: depth) in the range of [-64,d63].

This inodified aiming stray, POWERdS, is ready to display aftr sending to the host comnpute.

6. SPECTRORA DISPLAY PREPARATION. Ppre the pctrogam display via -the following steps: a) Subtract t&9 n5er-selectc4 noise floor9 pnnctrr from the aWay Pd-Pd Pd-spectrani nise, b) Rescade the spectra data to conltain 2.56 colors a-oss the user-specifled dynami .c raale--Pd3=#rPd226specr2Jrange, a) trnnatelclip the data to be integer valued from 0 to 2 s5S-pd4-nn2zss,o~rgPd)), d) tumeate the data to 8 bits-Pd5= bit tzuncate(.Pd4).

7. AUDIO OUTPUT. Sedtea-'RIIl 1 h ih n etpac audio ourputs to the speakers vAn port writes.

S. ROPUT MICROPHONE Sam ple M values into vector MIC from the input nmicrophonr, port (m is or transmit Pulse repetitions within an Sins period).

COME 0D No: SMBI-00532034 Received by IP Australia: Time 17:17 Date (V-M-cl) 2003-12-11 11/12 '03 THU 17:11 FAX 61 2 9888 7600

WATERMARK

0032 23 9. EMBOLUS DETECTION: BACKGROUND POWER IN POWER TRACES. For each of the four power traces, POWER TRACELPOWER TRACE4, corresponding to the four preset gate depths, compute a background power level. Recall that POWER TRACEn contains M values, where M is of transmit pulse repetitions within an ims period). The background power value is obtained by a delta-follower for each tace, and is denoted by 51, 82, 63, and d 84.

81new=Blold+A, where A=sign(lold-mean(PO _TRACEl)) U. dB.

B2newa2old+A, where A=sign(f2old-mcan(R TRACE2)) 0.dB.

83new=83old+A, where Asign(83pld-man(POWER TRACE3)) 0ldB.

64new84old+4, where A=sign(4old-manr(POWRTRACE4)) 0.1dB.

This update in the background values is done once every M power values, or every 8ms.

EMBOLUS DETECTION: PARABOLIC FIT. Apply a parabolic fit algorithm to the power trace each gate and determnine if an event is occuning during the 8ms period. This fit must be applied to successive data windows spaced apart by at most Ims. If the parabolic fit is concave down, and has a peak that exceeds the background power for the gate depth by 6 dB (an arbirary threshold), then an event is detected.

11. EMBOLUS DETECTION: TIME DETERMINATION. For any singlegate events, compute the exact time of the event by analyzing the power trace between the -6dB points on either side of the peak power of the cvm. Record event results and times so that current events may be compared to past ones.

12. EMBOLUS DETECTION: HIGH LEVEL CALCULATION. If the following conditions are true, then set DETECTION=TRUE: a) at least two adjacent of three gates in vicinity of blood flow show events within a COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THiT 17:11 FAX 61 2 9888 7600WAEMR 03

WATERMARK

Z 033 24 4 0 un time window, 19 the gate outside the blood flow shows no detection, und c) the limin of events shows progression in the directon of blood flow (Lae, the embolus is not swimmingupstream).

13. Pass Or, Cu. POWER4S PdS, SYSTOLEFLAG. VEND, VhMAN, VPEAK, MIC and DETECTION to host -for further pro1cessing, Rcfcuing to Figure 16, the embolus chractcizaioz subroutine operatons of digita signal processor, P3 are as follows: 4A- CALCUILAT.EMATrRIXELMENT MAGNLTUE5of Hr +ijM HnMas(64.M)=1o*oga0Qj.A2+H 4

.LA)

4a. CALCULATEl REFflEc BACKojRoUMq POWER LEVEL Pb.

11m-su(sm(Tn~L41:M))I IF PbOLD)>Hc~ TIEN PI=-PbOLD-0. dE3, ELSE PlrzPbOLD)ra 1dB. (This is a delta *follower of the background power level).

4C. DEThRMENAflON O]F I and R, constants to be used in chamcteriztim Ti=rnnuit barat lengthi in Microsecornds. ?2-pulse repetition peaio4, in mnicrosecny& We know a pflofl tat elements of H06)ate attached to 1mm increment in depth. Then Rlrala resolution in fllf=(7*fl/a, where c,11.S4invnicrosecon&, an R2t2SRI.

For -exampeit 320 CYcle transmit burst at 2M4Hz cardier frequencyba R172mzn, where R2a44nuy a ]DETECT EMOLUS SIGNATURE by mmining each column of Hunag(l:64,J:M) and determiig longest Contiguous segment of data such that each element in the contiguous segment is greater tha Pb+XdB (XC1, More specificatly, let HKIl:64)=-Hmagc1:cttakj Locate longest sequenc within Hit, demarcated by startinogand ending indices MHJl~2X such that 1{kQ)>Th+X if f<jcl*The length of. this sequenc~e is then detcnjed by fining the firs three points of HI(il:i2) with a Parabola, and fndng the left Most poinit on the abscissa, 2, where the ~parbola crosses the ordinate of Pb. If the Parabola does not intersect the COMS ID No: SMRI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:12 FAX 61 2 9888 7600 WATERMARK 0034 79 line rPb th. zl=il. Similarly, the last three points of k(iiZ) are fited with a parabola and z2 is located. If the parabola does not intrsect the line rPb. then z2i2. The length ofHkk(li2) is 2-zl. IF z2-zl<RJl then no embohus is present If RI<z2-zlcR2 then a particulate is present Ifz2-zl> then a bubble is present 4E. Pass this infomnation along to P4. If P4 agrees that a embolus is being detected, then attach the characterizmron infomation.

Those skilled in the arsit will appreciate that the invention may be accomplished with circuits other than those particularly depicted and described min connection with Figures 9-11. These figumes represent just one of many possibleimplementaions of a Doppler ultrasound system in accordance with the invention. Likewise, the invention may be accomplished using process steps other than those particularly depicted and described in connection with Figwr 12-16.

Those silled in the at will also understand that each of the circuits whose functions and intcrconnections are described in conhection with Figures 9-11 is of a type known in the art Therefore, one skilled in the art will be readily able to adapt such circuits in the described combination to practice the invention Particular details of these circuits are not critical to the invention, and a detailed description of the internal circuit operation need not be provided Similarly, each one of the process steps described in connection with Figures 12- 16 will be undestood by those silled in the art, and may itself be a sequence of operations that need not be described in detail in order for one sIdilled in the art to practice the invention.

It will be appreciated that, although specifc embodiments of the invention have been described for puposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. For example, a user interface in accordance with the present invention may be provided by means other than a video display, such as a printer or other visual COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:12 FAX 81 2 9888 7600 WATERMARK S035 26 display device. Those skilled in the art will also appreciate that many of the advantages associated with these circuits and processes described above may be provided by other circuit configurations and processes. Accordingly, the invention is not limited by the particular disclosure above, but instead the scope of the invention is determined by the following claims.

Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11

Claims (99)

1. A Doppler ultrasound system for providing blood flow information of a subject, the system including: an ultrasound transducer from which ultrasound signals are emitted into the subject along an ultrasound beam axis; an ultrasound receiver detecting echo signals resulting from the ultrasound signals emitted into the subject; an analog-tc-digital converter (ADC) circuit coupled to the ultrasound receiver to quantize the echo signals received by the ultrasound receiver into digital sample values; a digital signal processor coupled to the ADC circuit for processing the digital sample values to calculate blood flow velocity data and detected Doppler signal power data as functions of time for a plurality of locations along the ultrasound beam axis; a graphical display; and a display controller coupled to the digital signal processor and the graphical display for controlling the graphical display to display blood flow velocity data and detected Doppler signal power data as a graphical image representative of blood flow detected along the ultrasound beam axis as .a function of time, the graphical image having a color at each of the locations along the ultrasound beam axis for which data is displayed based on the blood flow velocity data and the color having a color property that varies based on the detected Doppler signal power data.

2. The system of claim 1, wherein the property of the color that is varied based the detected Doppler signal power data includes the intensity of the color.

3. The system of claim 1 or 2, wherein the digital signal processor includes: first processing circuitry for processing the digital sample values to calculate data representative of quadrature vectors, each quadrature vector having a first vector component and a second vector component; COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:12 FAX 61 2 9888 7600 WATERMARK ID037 28 digital filter circuitry coupled to the first processing circuitry for processing the data representative of the quadrature vectors to provide filtered quadrature vector data, the filtered quadrature vector data representative of the quadrature vectors having noise from outside a bandwidth of interest removed; clutter removal circuitry coupled to the digital filter circuitry for processing the filtered quadrature vector data to provide clutter cancelled vector data, the dutter cancelled vector data representative of the filtered quadrature vector data having contribution from stationary reflectors removed: and second processing circuitry coupled to the clutter removal circuitry for processing the clutter cancelled vector data to provide the blood flow velocity data and the detected Doppler signal power data as functions of time for the plurality of locations along the ultrasound beam axis.

4. The system of claim 3, wherein the first and second vector components includes a real vector component and an imaginary vector component, respectively. The system of any one of the preceding claims, wherein a first color of the graphical image is representative of. blood flow in a first direction, and a second color of the graphical image is representative of blood flow in a second direction.

6. The system of any one of the preceding claims, wherein the display controller further controls the graphical display to display locations along the ultrasound beam axis at which blood flow is not detected.

7. The system of any one of the preceding claims, wherein the graphical display is a first graphical display, and the system further includes a second graphical display coupled to the display controller, the display controller controlling the second graphical display to display a spectrogram indicating blood flow velocities as a function of time for a selected location along the ultrasound beam axis. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:13 FAX 61 2 9888 7600 WATERMARK 038 29

8. The system of claim 7, wherein the display controller further controls the first graphical display to display a location Indicator identifying the selected location along the ultrasound beam axis for which the spectrogram is displayed.

9. The system of claim 7 or 8 wherein the first and second graphical displays are displayed simultaneously. A data processing engine for a Doppler ultrasound system having an ultrasound transducer from which ultrasound signals are emitted into the subject along an ultrasound beam axis, an ultrasound receiver detecting echo signals resulting fmm the ultrasound signals emitted into the subject, and a color graphical display, the data processing engine including: an analog-to-digital converter (ADC) circuit coupled to the ultrasound receiver to quantize the echo signals received by the ultrasound receiver into digital sample values, the digital sample values stored as sample vectors; a digital signal processor coupled to the ADC circuit for processing the digital Sample vectors to calculate blood flow data and detected Doppler signal power data as functions of time for a plurality of locations along the ultrasound beam axis; and a display controller coupled to the digital signal processor and the graphical display for controlling the graphical display to display the blood flow data and the detected Doppler signal power data as a graphical image representative of the blood flow detected along the ultrasound beam axis as a function of time, the graphical image having a color at each of the locations for which data is displayed based on the blood flow data and the color having a color property that varies based on the detected Doppler signal power data.

11. The data processing engine of claim 10 wherein the property of the color that is varied based the detected Doppler signal power data includes the intensity of the color. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUI 17:13 FAX 61 2 9888 7600 WATERMARK oa039

12. The data processing engine of claim 10 or 11, wherein processing the digital sample vectors by the digital signal processor to calculate blood flow data includes calculating a mean blood flow velocity for the plurality of locations along the ultrasound beam axis and the display controller controls the graphical display to display a color at each of the locations for which data is displayed that is representative of the direction of blood flow.

13. The data processing engine of claim 12 wherein the display controller further controls the graphical display to display color regions corresponding with the locations at which blood flow is detected, the color of the color regions having a varying color property as a function of a detected Doppler signal power and mean blood flow velocity.

14. The data processing engine of claim 13, wherein the property of the color that is varied as a'function of the detected Doppler signal power and mean blood flow velocity includes the intensity of the color. The data processing engine of any one of claims 10 to 14, wherein the digital signal processor includes: first processing circuitry for processing the sample vectors to calculate data representative of quadrature vectors; digital filter circuitry coupled to the first processing circuitry for processing the data representative of the quadrature vectors to provide filtered quadrature vector data, the filtered quadrature vector data representative of the quadrature vectors having noise from outside a bandwidth of interest removed; clutter removal circuitry coupled to the digital filter circuitry for processing the filtered quadrature vector data to provide clutter cancelled vector data, the clutter cancelled vector data representative of the filtered quadrature vector data having contribution from stationary reflectors removed; and COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:13 FAX 61 2 9888 7600 WATERMARK Z040 31 second processing circuitry coupled to the clutter removal circuitry for processing the clutter cancelled vector data to provide the blood flow velocity data and the detected Doppler signal power data.

16. The data processing engine of claim 15, wherein the first processing circuitry includes processing circuitry for calculating data representative of quadrature vectors, each quadrature vector having a first vector component and a second vector component.

17. The data processing engine of claim 16, wherein the first and second vector components includes a real vector component and an imaginary vector component

18. The data processing engine of any one of claims 10 to 17, wherein the display controller further controls the graphical display to display a spectrogram indicating blood flow velocities as a function of time for a selected location along the ultrasound beam axis.

19. The data processing engine of claim 18, wherein the display controller further controls the graphical display to display a location indicator identifying the selected location along the ultrasound beam axis for which the spectrogram is displayed, The data processing engine of claim 18 or 19, wherein the graphical image representative of the blood flow data and the spectrogram are displayed simultaneously.

21. A method for providing blood flow information of a subject to which a Doppler ultrasound system emitting pulsed ultrasound signals along an ultrasound beam axis and detecting echo signals resulting therefrom is applied, the method including the steps of; for each pulse of ultrasound, quantizing the detected echo signals to generate a plurality of digital sample values representative of the echo signals; COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUI 17:14 FAX 61 2 9888 7600 WATERMARK M041 32 processing digital sample values of the pulses of ultrasound to calculate data representative of blood flow information as a function of time including detected Doppler signal power data for a plurality of locations along the ultrasound beam axis; and displaying the data representative of the blood flow information for the plurality of locations along the ultrasound beam axis as a function of time, the blood flow information displayed as having an associated color at each of the plurality of locations, the associated color having a color property that varies based on the detected Doppler signal power data.

22. The method of claim 21, wherein the color property that is varied based the detected Doppler signal power data includes the intensity of the color.

23. The method of claim 21 or 22, further including the step of calculating filter coefficients based on the rate at which the detected echo signals are quantized, wherein the step of processing the digital sample values includes the steps of: generating a quadrature vector from the plurality of digital sample values of each pulse of ultrasound; processing each quadrature vector using the filter coefficients to calculate filtered quadrature vector data representative of the quadrature vector having noise from outside a bandwidth of interest removed; calculating from a plurality of quadrature vectors clutter cancelled vector data representative of the filtered quadrature vectors having contribution from stationary reflectors removed from the filtered quadrature vectors; and calculating the detected Doppler signal power for the plurality of locations along an ultrasound beam axis from the clutter cancelled vector data.

24. The method of claim 23, wherein the quantizing step includes the step of quantizing the detected echo signals at four times the frequency of the emitted ultrasound signals. The method of claim 24, wherein the generating step includes the steps of: COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:14 FAX 61 2 9888 7600 WATERMARK 1042 33 dividing the sample values into sets of four values, each set having first, second, third and fourth values; and for each set, subtracting the third from the first values to generate a real vector component of the quadrature vector and subtracting the fourth from the second values to generate an imaginary vector component of the quadrature vector.

26. The method of any one of claims 21 to 25, wherein the step of processing the digital sample values further includes the step of calculating mean blood flow velocity data as a function of time for locations along the ultrasound beam axis and the step of displaying the data representative of blood flow information includes the step of displaying a first color representative of blood flow in a first direction and displaying a second color representative of blood flow in a second direction.

27. The method of claim 26 wherein the step of displaying the data representative of blood flow information further includes the step of displaying color regions corresponding to blood flow detected as having a blood flow velocity exceeding a velocity threshold.

28. The method of claim 27, wherein the velocity threshold is user programmable.

29. The method of any one of claims 21 to 28, wherein the step of displaying the data representative of blood flow information includes the step of displaying color regions corresponding with the locations at which blood flow is detected having detected Doppler signal power exceeding a power threshold.

30. The method of claim 29, wherein the power threshold is user programmable. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THIU 17:14 FAX 61 2 9888 760 ATRAR O WATERMARK 10043 34

31. The method of any one Of claims 21 to 30, further including the step of displaying spectral graphical information indicating blood flaw velocities at the selected one of the displayed locations.

32. The method 0of clai m 31. wherein the data representative of blood flow information for the plurality of locations along the ultrasound beam axis and spectral information are displayed simultaneously.

33. The method of claim 31 or 32, further including the step of displaying a location indicator identfyng the selected one of the displayed locations,

34. The method of any one of claims 21 to 33. further including the step of displaying locations along the ultrasound beam axis at which blood flow is not detected. A method for providing blood flow information of a subject to which a Doppler ultrasound system emitting ultrasound signals along an ultrasound beam axis and detecting echo signals resulting therefrom is applied,, the method including the steps of. quantizing the detected echo signals to generate a plurality of digital sample values representative of the echo signals; generating quadrature vectors from the plurality of digital sample values; processing the quadrature vectors to calculate blood flow data and detected Doppler signal power data as functions of time for a plurality of locations along the ultrasound beam axis; and displaying the blood flow data and the detected Doppler signal power data ors a graphical image representative of blood flow detected along the ultrasound beam axis as a function of time, the detected blood flow displayed as having a color at each of the locations for which data is displayed based on the blood flow data and the color having a color property based on the detected Doppler signal power data. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:14 FAX 61 2 9888 7600 WATERMARK Z044

36. The method of claim 35, wherein the color property that is varied based the detected Doppler signal power data includes the intensity of the color.

37. The method of claim 35 or 36, wherein the quantizing step includes the step of quantizing the detected echo signals at four times the frequency of the emitted ultrasound signals.

38. The method of claim 37, wherein the step of generating quadrature vectors from the plurality of digital sample values includes the steps of: dividing the sample values into sets of four values, each set having first, second, third and fourth values; and for each set, subtracting the third from the first values to generate a real vector component of the quadrature vector and subtracting the fourth from the second values to generate an imaginary vector component of the quadrature vector.

39. The method of any one of claims 35 to 38. further including the step of calculating filter coefficients based on the rate at which the detected echo signals are quantized, wherein the step of processing the quadrature vectors to calculate blood flow data and detected Doppler signal power data includes the steps of: processing each quadrature vector using the filter coefficients to calculate filtered quadrature vector data representative of the quadrature vector having noise from outside a bandwidth of interest removed; calculating from the data fur a plurality of quadrature vectors clutter cancelled vector data representative of the filtered quadrature vectors having contribution from stationary reflectors removed from the filtered quadrature vectors; and calculating the detected Doppler signal power for each of the first plurality of locations along an ultrasound beam axis from the clutter cancelled vector data. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUL 17:15 FAX 61 2 9888 7600WAEAR J04 WATERMARK 4045 36 The method of any one of claims 35 to 39, further including the step of Processing the quadrature vectors to calculate a mean velocity for each of the plurality of locations along the ultsound beam awus.

41. The method of any one of claims 35 to 40, further including the step of displaying spectral graphical information indicating blood flow velocities at the selected one of the displayed locations.

42. The method of claim 41, wherein the graphical image representtive of blood flow detected along the ultrasound beam axis and spectral information are displayed simultaneously. 43, The method of claim 41 or 42, further including the stop of displaying a location indicator Identifying the selected one of the displayed locations,

44. The m-ethod of any one of claims 35 to 43, further including the step of displaying locations along the ultrasound beam axis at which blood flow is not detected. The method of any one of claims 35 to 44, whereln the step of displaying the graphical image representative of blood flow detected along the ultrasound beam axis includes the step of displaying a first color representative of blood flow in a first direction and displaying a secornd color representative of blood flow in a second direction.

46. The method of any one of claims 35 to 45, wherein the step of displaying the graphical image representfaiy of blood flow detected along the ultrasound beam axis includes the step of displaying color regions corresponding with the locations at which blood flow is detected as having a blood flow velocity exceeding a velocity threshold. COMIS ID NO: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THUT 17:15 FAX 61 2 9888 7600WARAK 04 WATERMARK 10046 37

47. The mnethod Of claim 46. wherein the velocity threshold is user programmable.

48. The Method of any one Of claims 35 to 47, wherein the step of displaying the graphical image representative of blood flow detected along the ultrasound beam axis Includes the step of displaying color regions corresponding with the locations at which blood flow is detected having detect ed Doppler signal power exceeding a power threshold.

49. The method of claim 48, wherein the power thresholdi Is user programmable. A computer-readable medium having computer executable instructions for controlling digital processing circuitry in a Doppler ultrasound system to process detected ultrasound echo signals and provide blood flow information, hr controlling an analog-o..digih; converter (ADC) circuit to quantize the detected ultrasound echo signuls to generate a plurality of digital sample values representative of the ultrasound echo signal; generating quadrature vectors from the plurality of digital sample values; processing the quadrature vector-s to calculate blood flow data as a function of time including detected Doppler signal power data for a plurality of locations along the ultrasound beam-r axis; and processing the blood flow data for display as a function of time for the plurality of locations along the ultrasound beam axis, the blood flow data displayed as having an associated color at each of the plurality of locations indicative of blood flow velocity and the associated color having a color property based on the detected Doppler signal power data. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:15 FAX 61 2 9888 7600 WATERMARK [047 38

51. The computer readable medium of claim 50, wherein the computer executable instructions for processing the blood flow data includes processing the blood flow data to be displayed as having an associated color at each of the plurality of locations and the associated color having a color intensity based on the detected Doppler signal power data.

52. The computer readable medium of claim 50 or 51, wherein the computer executable instructions for controlling the ADC circuit includes computer executable instructions for controlling the ADC circuit to quantize the detected echo signals at four times the frequency of the emitted ultrasound signals.

53. The computer readable medium of claim 52, wherein the computer executable instructions for generating quadrature vectors from the plurality of digital sample values includes computer executable instructions for: dividing the sample values Into sets of four values, each set having first. second, third and fourth values; and for each set, subtracting the third from the first values to generate a real vector component of the quadrature vector and subtracting the fourth from the second values to generate an imaginary vector component of the quadrature vector.

54. The computer readable medium of any one of claims 50 to 53, further Including computer executable instructions for calculating filter coefficients based on the rate at which the detected echo signals are quantized, wherein the computer executable instructions for processing the quadrature vectors to calculate blood flow data and detected Doppler signal power data includes computer executable instructions for processing the quadrature vectors using the filter coefficients to calculate filtered quadrature vector data representative of the quadrature vectors having noise from outside a bandwidth of Interest removed; COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:16 FAX 61 2 9888 7600 WATERMARK 048 39 calculating clutter cancelled vector data representative of the filtered quadrature vector data having contribution from stationary reflectors removed from the filtered quadrature vector data; and calculating the detected Doppler signal power as a function of time for the plurality of locations along an ultrasound beam axis from the clutter cancelled vector data. The computer readable medium of any one of claims 50 to 54, further including computer executable instructions for processing the quadrature vectors to calculate a mean velocity for the plurality of locations along the ultrasound beam axis.

56. The computer readable medium of any one of claims 50 to 55, further including computer executable instructions for processing the blood flow data to display spectral graphical information indicating blood flow velocities at the selected one of the displayed locations.

57. The computer readable medium of any one of claims 50 to 56, further including computer executable instructions for processing the blood flow data to display locations along the ultrasound beam axis at which blood flow is not detected.

58. The computer readable medium of any one of claims 50 to 57. wherein the computer executable Instructions for processing the blood flow data for display includes computer executable instructions for processing the blood flow data to display a first color representative of blood flow in a first direction and displaying a second color representative of blood flow in a second direction. COMS ID No: SMBI-00532034 Received by IP Australia: Time 17:17 Date 2003-12-11 11/12 '03 THU 17:17 FAX 61 2 9888 7600 WmIR 0 WATERMARK Q 002

59. The computer readable medium of any one of claims 50 to 58, wherein the computer executable instructions for processing the blood flow data for display includes computer executable instructions for processing the blood flow data to- display color regions corresponding with the locations at which blood flow having a blood flow velocity exceeding a velocity threshold. The computer readable medium of any one of claims 50 to 59, wherein the computer executable instructions for processing the blood flow data for display includes computer executable instructions for processing the blood flow data to display color regions corresponding with the locations at which blood flow is detected having detected Doppler signal power exceeding a power threshold.

61. A Doppler ultrasound system for processing ultrasound signals along an ultrasound beam axis and for displaying information to a usor concerning blood flow, including: an ultrasound transducer operable to detect ultrasound signals and responsively produce corresponding electrical signals; a graphical display device; and signal processing circuitry coupled to the transducer and operable to receive the electric signals and determine blood flow characteristics corresponding with the detected ultrasound signals, the signal processing circuitry further coupled to the graphical display device and operable to process the detected ultrasound signals and provide data to the graphical display to display blood flow information along a time domain for a plurality Of locio~ns along the ultrasound beam axis a depiction of detected blood flow having intensity varying as a function of detected Doppler ultrasound amplitude.

62. The Doppler ultrasound system of claim 61, wherein the signal processing circuitry is further operable to process the detected ultrasound signals and provide data to the graphical display to display spectral graphical information Indicating blood flow velocities at a selected one of the plurality of locations- COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:17 FAX 61 2 9888 7600 WATERMARK I003 41

63. The Doppler ultrasound system of claim 62, wherein the selected one of the plurality of locations is indicated by a location indicator displayed on the graphical display device.

64. The Doppler ultrasound system of any one of claims 61 to 63, wherein the graphical display device is operable to display the plurality of locations at which blood flow is detected and the spectral graphical information are displayed simultaneously. The Doppler ultrasound system of any one of claims 61 to 64, wherein the signal processing circuitry Is further operable to process the detected uttaound signals and provide data to the graphical display to display a color region corresponding with the locations at which blood flow is detected, the color of the color region having an intensity varying with the detected Doppler ultrasound amplitude and detected blood flow velocity.

66. The Doppler ultrasound system of claim 65, wherein the color of the color region comprises first or second colors, the first and second colors associated' with blood flow in first and second directions, respectively.

67. The Doppler ultrasound system of any one of claims 61 to 66, wherein the signal processing circuitry is further operable to process the detected ultrasound signals and provide data to the graphical display to display along the time domain for a plurality of locations along the ultrasound beam axis a depiction of where blood flow is not detected.

68. A method in a Doppler ultrasound system for providing information to a user concerning blood flow, including the steps of: displaying blood flow information as a function of time for a plurality of locations along an ultrasound beam axis at which blood flow is detected; and COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:17 FAX 61 2 9888 7600 WATERMARK o00o4 42 varying display intensity as a function of detected Doppler ultrasound amplitude and detected blood flow velocity at each of the locations.

69. The method of claim 68, further including the step of displaying velocities of monitored blood flow at a selected one of the displayed locations. The method of claim 69, wherein the step of displaying velocities of monitored blood flow includes displaying spectral graphical information indicating blood flow velocities at the selected one of the displayed locations.

71. The method of any one of claims 68 to 70, wherein the step of displaying the plurality of locations at which blood flow is detected includes displaying color regions corresponding with the locations at which blood flow is detected.

72. The method of claim 71, wherein the step of displaying the plurality of locations at which blood flow is detected further includes displaying first and second colors associated with blood flow in first and second directions, respectively.

73. The method of claim 71, wherein the step of displaying the plurality of locations at which blood flow is detected further includes displaying first and second colors associated with blood flow in first and second directions, respectively, and wherein the step of varying display intensity includes varying color intensity of the color regions.

74. The method of any one of claims 68 to 70, wherein the step of displaying the plurality of locations at which blood flow is detected includes displaying color regions corresponding with the locations at which blood flow having a blood flow velocity exceeding a velocity threshold is detected. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:18 FAX 61 2 9888 7600 WATERMARK b005s 43 The method of any one of claims 68 to 70, wherein the step of displaying the plurality of locations at which blood flow is detected includes displaying color regions corresponding with the locations at which blood flow is detected having detected Doppler ultrasound amplitude exceeding a power threshold.

76. A Doppler ultrasound system for providing blood flow information of a subject, substantially as hereinbefore described with reference to the accompanying drawings.

77. A data processing engine for a Doppler ultrasound system, substantially as hereinbefore described with reference to the accompanying drawings.

78. A method of providing blood flow information of a subject to which a Doppler ultrasound system is applied, substantially as hereinbefore described with reference to the accompanying drawings.

79. A computer-readable medium having a computer executable instructions for controlling digital signal processing circuitry in a Doppler ultrasound system, substantially as hereinbefore described with reference to the accompanying drawings. A Doppler ultrasound system for processing ultrasound signals along on ultrasound beam axis and for displaying information to a user concerning blood flow, substantially as hereinbefore described with reference to the accompanying drawings. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:18 FAX 61 2 9888 7600 WATERMARK oo006 44

81. A method in a Doppler ultrasound system for providing information to a user concerning blood flow, substantially as hereinbefore described with reference to the accompanying drawings. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 TBUL 17:18 FAX 61 2 9888 7600 WATERMARK oo 07 CLAMS 1. A user interface for output on a visual display device, the user interface providing information in connection with Doppler ultrasound monitoring of blood flow, comprising; a fixst graphical display indicating a plurality of locations along an ultrasound beam axis at which blood flow is detected and including a location indicator idcnti1ying a selected one of the locations; and a second graphical display indicating velocities of monitored blood flow at the selected location. 2. The user interface of claim I wherein the plurality of locations is a first plurality and wherein the graphical display indicates a second plurality of locations along the ultrasound beam axis at which blood flow is not detccted. 3. The user interface of claim I wherein the first graphical display includes first and second colors associated with blood flow in first and second directions, respectively. 4. The user interface of claim 1 wherein the first graphical display includes a color region corresponding with the locations at which blood flow is detected. The user interface of claim 1 wherein the first graphical display includes a color region corresponding with the locations at which blood, flow is detected, the color having varying intensity as a fonction of a detected Doppler ultrasound signal amplitude. 6. The user interface of claim I wherein the first graphical display includes a color region corresponding with the locations at which blood flow is COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:18 FAX 61 2 9888 7600WAhMR oo WATERMARK 2008 46 detected, the color associated with detected blood flow direction and having varying intensity as a flmiclion of a detected )Doppler ultrasound signal amplitude. 7. The user interface of claim 1 wherein the firs graphical display includes a color region corresponding wit the locations at which blood flow is detected, the color associated with detected blood flow direction and having varying intensity as a fimetion of detected blood flow velocities. 8. The user interface of claim I wherein the second graphical display is a spectrogram indicating the velocities of the tmonitored blood flow at the selected location as a fumction of time. 9. The user interface of claim I wherein the first graphical display includes a color region corresponding with the locations at which blood flow is detected, the location indicator being a pointer direczed towards a position within the color region, and wherein the second graphical display is a spectrogram indicating the velocities of the monitored blood flow at the selected location as a finction of time. The user interface of claim I wherein the first graphical display indicates the plurality of locations at which blood flow is detected as a -tunction of time.. 11. The user interface of claim 1 wherein the first and second gra~hica1 displays are provided simultaneously. 12. ,A graphical display for providing information in connection with Doppler ultrasound monitoring of blood flow, comprising: a blood locator display depicting a plurality of locations along an ultrasound beam axis at which blood flow is detected; and COMS ID No: SMBI-00532124 Received by IP Australia: Time (I-tm) 17:28 Date 2003-12-11 11/12 '03 THU 17:19 FAX 61 2 9888 7600 WATERMARK [ao09 47 a spectrogram depicting detected blood flow velocities as a ftmction of time at a selected one of the locations. 13.. The graphical display of claim 12, further comprising a location indicator identifying the selected location. 14. The graphical display of claim 13 wherein the location indicator is a pointer directed to the selected location depicted in the blood locator display. The graphical display of claim 12 wherein the blood locator display includes a color region corresponding to the depicted locations at which blood flow is detected, the color having varying intensity as a function of a detected DLoppler ultrasound signal amplitude. 16. The graphical display of clain 12 wherein the blood locator display includes a color region corresponding to the depicted locations at which blood flow is detected, the color associated with blood flow direction and having varying intensity as a function of a detected Doppler ultrasound signal amplitude, 17. The graphical display of claim. 12 wherein the blood locator display includes a color region corresponding to the depicted locations at which blood flow is detected, the color associated with blood flow direction and having varying intensity as a function of a detected blood flow velocities. 18. A graphical display for providing information in connection with Doppler ultrasound monitoring of blood flow, comprising: a blood locator display having a color region depicting a plurality of locations along an ultrasound beam axis at which blood flow is detected, and including a location indicator identifying a selected one of the locations; and COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:19 FAX 61 2 9888 7600 WATERMARK O00O 48 a spectrogram depicting detected blood flow velocities as a function of time at the selected location. 19. The graphical display of claim 18 wherein the location indicator is a pointer directed towards a position within the color region corresponding to the selected location. The graphical display of claim 18 wherein the color region has one of first and second colors corresponding with first and second detected blood flow directions. 21. The graphical display of claim of claim 18 wherein the color region has one of first and second colors corresponding with first and second detected blood flow directions, the intensity of the color varying as a function of a detected one of blood flow velocity and Doppler ultrasound signal amplitude. 22. Thc graphical display of claim 18 wherein the location indicator is a pointer directed towards a position within the colored region corresponding to the selected location, and wherein the colored region has one of first and second colors corresponding with first and second detected blood flow directions, the intensity of the color varying as a fnction of a detected one of blood flow velocity and Doppler ultrasound signal amplitude. 23. A Doppler ultrasound system for processing ultrasound signals along an ultrasound beam axis and for displaying information to a user concerning blood flow, comprising: an ultrasound transducer operable to detect ultrasound signals and responsively produce corresponding electrical signals; COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THUL 17:19 FAX 61 2 9888 7600WARAK jOi WATERMARK [a oil 49 signal processing circuitry coupled with the transducer and operable to receive the electrical signals and determine blood flow characteristics corresponding with the deteced ultrasound signals, a display coupled with the signal processing circuitry and operable, to provide graphical information to the user corresponding wit the determnined blood flow characteristics, the display providing aiming graphical infornation indicating a plurality of locations along the beam axis at which blood flow is detected, the display further providing spectral graphical infonnuation indicating blood flow velocities at a selected one of the locations, aind the display fivcrhr providing a location indicator identify'ing the selected location. 24. The Doppler ultrasound system of claim 23 wherein the aiming graphical information includes a color region corresponding with the locations at which blood flow is detected, the color asociated with blood flow direction and having varying intensity as a function of one of detected blood flow velocity and detected Doppler ultrasound signial strength, and wherein the location indicator is a pointer directed towards a position within the colored region correspondinlg to the selected location. The Doppler ultrasound system of claim 23 wherein the display provides the aiming and spectral graphical information simultaneously- 26. In a Doppler ultrasound system for processing ultrasound signals along an ultrasound beam axis, a method of providing information to a user concerning blood flow, comprising: displaying first graphical information depicting Wlood flow at a plurality of locations along the beam axis; and displaying second graphical informnation depicting blood flow velocities at a selected one of the locations, the first and second graphical information being displayed simultaneously. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:19 FAX 61 2 9888 7600 WATERMARK IM 01 so 27. The method of claim 26 wherein displaying the first graphical information includes displaying a location indicator directed to the selected location. 28. The. method of claim 26 wherein the -selected location is determined by the user. 29. The method of claim 26 wherein displaying the first graphical information includes displaying a color region corresponding with locations where blood flow is detected. The method of claim 26 wherein displaying the first graphical infornation includes displaying color having a vaying intensity in correspondence with detected Doppler ultrasound signal amplitude. 31. The method of claim 26 wherein displaying the first graphical information includes displaying one of first and second colors corresponding to blood flow in first and second directions, respectively. 32. The method of claim 26 wherein displaying the first graphical information includes displaying one of first and second colors corresponding to blood flow in first and second directions, respectively, and varying the intensity of the first and second colors in correspondence with detected blood flow velocities. 33. The method of claim 26 wherein displaying the first graphical information includes displaying one of first and second colors corresponding to blood flow in first and second directions, respectively, and varying the intensity of the first and second colors in correspondence with detected Doppler ultrasound signal amplitude. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:20 FAX 61 2 9888 7600 WATERMARK [a1013 51 34. The method of claim 26 wherein displaying the first graphical information includes depicting the blood flow at the plurality of locations as a function of time. In a Doppler ultrasound system for processing ultrasound signals along an ultrasound beam axis, a method of detecting and characterizing emboli in blood flow, comprising: determining a first plurality of locations along the beam axis in which blood flows and determining a second plurality of locations along the beam axis in which blood does not flow; determining the direction in which the blood flows at each of the first locations; and if a first ultrasound signal having an intensity greater than a threshold intensity is received, then: determining if the first ultrasound signal corresponds ,with the first locations; determining if the first ultrasound signal corresponds with the second locations; determining if the first ultrasound signal corresponds with the determined direction and velocity of the blood flow; if the first ultrasound signal does not correspond with the determined direction or velocity of the blood flow, then identifying the first ultrasound signal as a non-embolic signal; if the first ultrasound signal corresponds with the detenrmined direction or velocity of the blood flow, and if the first ultrasound signal corresponds solely with the first locations, then identifying the first ultrasound signal as an embolic signal of a first type; and if the first ultrasound signal corresponds with the determnnined direction and velocity of the blood flow, and if the first ultrasound signal corresponds COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:20 FAX 61 2 9888 7600 WATERMARK 1014 St 52 both with the first and second locations, then identifying the first ultrasound signal as an embolic signal of a second type. 36. The method of claim 35, further comprising selecting one of the first locations, and wherein the first ultrasound signal is a signal corresponding with the selected location. 37. The method of claim 35 wherein determining the first plurality of locations in which blood flows includes displaying graphical information having a color region corresponding to the first locations. 38. The method of claim 35 wherein determining the first plurality of locations in which blood flows includes displaying graphical information having a color region corresponding to the first locations, and wherein determining the direction in which the blood flows at each of the first locations includes selecting one of first and second colors for the color region, the first and second colors corresponding with first and second blood flow directions along the beam axis, respectively. 39. The method of claim 35 wherein determining the first plurality of locations in which blood flows includes displaying graphical information having a color region corresponding to the first locations, and varying the intensity of the color as a function of detected Doppler ultrasound signal intensity, and wherein determining if the first ultrasound signal corresponds with the first locations includes displaying a graphical event signal corresponding with the first ultrasound signal and determining if the graphical event signal is positioned within the color region. The method of claim 35 wherein determining the first plurality of locations in which blood flows includes displaying graphical information having a color region corresponding to the first locations, and varying the intensity of the color COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:20 FAX 61 2 9888 7600 WATERMARK 53 as a limction of detected Doppler ultrasound signal intensity, and wherein determining if the first ultrasound signal corresponds with the determined direction and velocity of blood flow includes displaying a graphical event signal corresponding with the first ultrasound signal and determining if the graphical event signal is positioned in a predetnmzined orientation relative to the color region. 41. The method of claim 35 wherein determining if the first ultrasound signal corresponds with the determined direction and velocity of blood flow includes detemining if the first ultrasound signal corresponds with a velocity not exceeding a maximum velocity of the blood flow. 42. In a Doppler ultrasound system for processing ultrasound signals along an ultasound beam axis, a method of locating a selected one of a plurality of blood vessels, comprising: determining a plurality of locations along the beam axis in which blood flows; displaying first graphical information depicting the locations at which blood flow is detected; determining the velocity with which blood flows in each of the locations; selecting a first one of the locations; displaying second graphical information depicting blood flow velocities at the first location; detecting a temporal variation in the first graphical information; detecting a temporal variation in the second graphical information; and determining, whether the detected temporal variations in the first and second graphical information corresponds with the selected blood vessel. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THUL 17:20 FAX 61 2 9888 7600 WATERMARK Z016 S4 43. The method of claim 42 wherein displaying the first graphical information includes displaying a color region corresponding with the locations at which blood flow is detected. 44, The method of claim 42 wherein displaying the first graphical information includes displaying a color region corresponding with the locations at which blood flow is detected, and varying the intensity of the color as a function of detected Doppler ulrasound signal intensity. The method of claim 42 wherein displaying the first graphical information includes displaying a color region corresponding with the locations at which blood flow is detected, and varying the intensity of the color as a function of the deternined blood flow velocities. 46. The. method of claim 42 wherein displaying the first graphical information includes displaying a color region corresponding with the locations at which blood flow is detected, and wherein detecting a temporal variation in the first graphical information includes detecting a temporal variation in the size of the color region. 47. The method of claim 42 wherein displaying the first graphical information includes displaying a color region corresponding with the locations at which blood flow is detected, and varying the intensity of the color as a function of the determined blood flow velocities, and whercin detecting a temporal variation in the first graphical information includes detecting a temporal variation in the color intensity of the color region. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:21 FAX 61 2 9888 7600WARAK I07 WATERMARK Z017 48. A computer readable medium whose contents configure a computer system to provide information to a user concerning blood flow detected by processing Doppler ultrasound signals along an ultrasaund beam axis, comprising; displaying first graphics] infornation depicting blood flow at a plurality of locations along the beam axis; and Idisplaying second graphical information depicting blood flow velocities at a selected one of the locations the first and second graphical information being displayed simultaneously. 49. The computer readable 'medim of claim 48 wherein displaying the firs graphical information includes displaying a location indicator directed to the selected location. The computer readable medium of claim 48 wherein the selected location is determined by a -user of the computer system. 51. The computer readable medium of claim. 48 wherein displaying the first graphical Information includes displaying a color region corresponding with locations where blood flow is deteced. 52. The computer readable medium of claim 48 wherein displaying the first graphical information includes displaying color having a varying intensity in correspondence with detected Doppler ultrasound signal amplitude. 53. The computer readable medium of claim 4S wherein displaying the first graphical information includes displaying one of first and second colors corresponding to blood flow in first and second directions, respectively. 54, The computer readable mediumn of claim 48 wherein displaying the first graphical information includes displaying one of first and second colors COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:21 FAX 61 2 9888 7600 WATERMARK 2018 56 coiresponding to blood flow in first and second directions, respectively, and varying the intensity of the first and second colors in correspondence with detected blood flow velocities. The computer readable medium of claim 42 wherein displaying the first graphical information includes displaying one of first and second colors corresponding to blood flow in first and second directions, respectively, and varying the intensity of the first and second colors in correspondence with detected Doppler ultasound signal amplitude. 56. The computer readable medium of claim 48 wherein displaying the first graphical information includes depicting the blood flow at the plurality of locations as a function of time. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THiU 17:21 FAX 81 2 9888 7600 WTRAKlii WATERMARK 0019 57 13S. A Doppler ultrasound system, comprising: an ultrasound transducer from which ultnd signals are em-itted into the subject along an ultrasound beam axis; an ultrasound receiver detecting echo signals resulting from the ultrasound signals emitted into the subject; an analog-to-digital converter (ADC) circuit coupled to the ultrasound receiver to quantize the echo signals received by the ultrasound receiver into digital sample values; and a processor coupled to the ADC circuit for processing the digital sample values to calculate blood flow velocity data as functions of time for a plurality of locations along the ultrasound beam axis, the processor further operable to generate data from the blood flow velocity data that is representative of blood flow velocity detected along the ultrasound beam axis as a function of time and having a component associated with blood- flow velocity at each of the locations along the ultrsound beam axis for which data is generated.

135.1. The system of claim 135 wherein the processor comprises a processor calculating detected Doppler signal power data as a function of time for a plurality of locations along the ultrasound beam axis and the processor is further operable to generate data that varies the blood flow velocity component based on the detected Doppler signal power data.

137. The system of claim 135 wherein the processor comprises: first processing circuitry for processing the digital sample values to calculate data representative of quadrature vectors, each quadrature vector having a first vector component and a second vector component; digital filter circuitry coupled to the first processing circuitry for processing the data representative of the quadrature vectors to provide filtered quadrature vector data, the COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THUT 17:21 FAX 61 2 9888 7600 WTRAK~ 2 WATERMARK [a 020 58 filtered quadrature vector data representative of the quadrature vectors having noise from outside a bandwidth of interest removed; clutter removal circuitry coupled to the digital filter circuitry for processing the filtered quadrature vector data to provide clutter cancelled vector data the clutter cancelled vector data representative of the filtered quadrature vector data having contribution from stationary reflectors removed; and second processing circuitry coupled to the clutter removal circuitry for processing the clutter cancelled vector data to provide the blood flow velocity data as a function of time for the plurality of locations along the ultrasound beam axis. 137. 1. The system of claim 137 wherein the second processing circuitry coupled to the clutter removal circuitry farther processes the clutter cancelled vector data to provide detected Doppler signal power data as a function of time for the plurality of locations along the ultrasound bean axis.

138. The system of claim 137 wherein the first and second vector components comprises a real vector component and an imaginary vector component, respectively.

139. 1The system of claim 135 wherein a first blood flow velocity colmponenlt is representative of blood flow in a first direction, and a second blood flow velocity component is representative of blood flow in a second direction.

141. The system of claim 135 wherein the processor coupled to the ADC is further operable to generate data indicating blood flow velocities as a function of time for a selected, location along the ultrasound beam axis.

144. A data processing engine for a Doppler ultrasound system having an ultrasound transducer from which ultrasound signals are emitted into the subject along an COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:22 FAX 61 2 9888 7600 WTRAK~ 2 WATERMARK [a 021 59 ultrasound beam axis and an ultrasound receiver detecting echo signals resulting from the ultrasound signals emitted into the subject, the data processing engine comprising: an analog-to-digital converter (ADC) circuit coupled to the ultrasound receiver to quantize the echo signals received by the ultrasound receiver into digital sample values, the digital sample values stored as sample vectors; and a processor coupled to the ADC circuit for processing the digital sample vectors to calculate blood flow data as a function of time for a plurality of locations along the ultrasound beam axis, the processor further operable to generate data from the blood flow data that is representative of the blood flow velocity detected along the ultrasound beam axis as a function of time and has a component associated with blood flow velocity at each of the locations for which data is generated. 144. 1. The data processing engine of claim 144 wherein the processor comprises a processor for processing the digital sample vectors to calculate detected Doppler signal power data as a function of time for a plurality of locations alonig the ultrasound beam axis, and further operable to generate data to vary the component based on the detected Doppler signal power data.

146. The data processing engine of claim 144 wherein processing the digital sample vectors by the digital signal processor to calculate blood flow data comprises calculating a mean blood tlow Velocity for the plurality of locations alon g the ultrasound beam axis and the display controller generates data to display a color at each of the locations for which data is displayed that is representative of the direction of blood flow.

149. The data processing engine of claim 144 wherein the digital signal processor compnises: first processing circuitry for processing the samnple vectors to calculate data representative of qoadrature vectors; COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:22 FAX 61 2 9888 7600 WTRAK~ 2 WATERMARK [a 022 digital filter circuitry coupled to the first processing circuitry for processing the data representative of the quadrature vectors to provide filtered quadrature vector data, the filtered quadrature vector data representative of the quadrature vectors having noise from outside a bandwidth of interest removed; clutter removal circuitry coupled to the digital filter circuitry for processing the filtered quadrature vector data to provide clutter cancelled vector data, the clutter cancelled vector data representative of the filtered quadrature vector data having contribution from stationary reflectors removed;- and second processing circuitry coupled to the clutter removal circuitry for processing the clutter cancelled vector data to provide the blood flow velocity data. 149.1- The system of claim 137 wherein the second processing circuitry coupled to the clutter removal circuitry further processes the clutter cancelled vector data to provide detected Doppler signal power data as a function of time for the plurality of locations along the ultrasound beam axis.

150. The data processing engine of claim 149 wherein the first processing circuitry comprises processing circuitry for calculating data representative of quadrature vectors, each quadrature vector having a first vector component and a second vector component.

151. The data processing engine of claim 150 wherein the first and second vector components comprises a real vector component and an imaginary vector component.

152. The data processing engine of claim 144 wherein the processor further generates data indicating blood flow velocities as a function of time for a selected location along the ultrasound beam axis. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THIT 17:22 FAX 61 2 9888 7600 WATERMARK IM023 61

169. In a Doppler ultrasound system emitting pulse ultrasound signals along an ultrasound beam axis and detecting echo signals resulting therefrom, a method for generating blood flow information of a subject to which the Doppler ultrasound system is applied, the method comprising: for each pulse of ultrasound, quantizing the detected echo signals to generate a plurality of digital sample values representative of the echo signals; and processing digital sample values of the pulses of ultrasound to calculate data representative of blood flow information that is representative of blood flow velocity detected along the ultrasound beam axis as a function of time and having a component associated with blood flow velocity at each of the plurality of locations along the ultrasound beam axis. 169.1. The method of claim 169, further comprising generating detected Doppler signal power data for a plurality of locations along the ultrasound beam axis and generating data that is representative of varying the component based on the detected Doppler signal power data.

171. The method of claim 169, further comprising calculating filter coefficients based on the rate at which the detected echo signals are quantized and wherein processing the digital sample values comprises: generating a quadrature vector from the plurality of digital sample values of each pulse of ultrasound; processing each quadrature vector using the filter coefficients to calculate filtered quadrature vector data representative of the quadrature vector having noise from outside a bandwidth of interest removed; and calculating from a plurality of quadrature vectors clutter cancelled vector data representative of the filtered quadrature vectors having contribution from stationary reflectors removed from the filtered quadrature vectors- and COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THUL 17:23 FAX 61 2 9888 7800 WTRAK~ 2 WATERMARK [a 024 62 171.!. The method of claim 171, further comprising calculating detected Doppler signal power for the plurality of locations along an ultrasound beam axis from the clutter cancelled vector data.

172. The method of claim 171 wherein quantizing comprises quantizing the detected echo signals at four times the frequency of the emitted ultrasound signals.

173. The method of claim 172 wherein generating quadrature vectors from the plurality of digital sample values of each pulse of ultrasound comnpr-ises: dividing the sample values into sets of four values, each set having first, second, third and fourth values; and for each set, subtracting the third from the first values to generate a real vector component of the quadrature vector and subtracting the fourth from the second values to grenerate an imaginary vector component of the quadrature vector.

174. The method of claim 169 wherein processing the digital sample values to calculate data representative of blood flow information further comprises calculating mean blood flow velocity data as a function of time for locations along the ultrasound beam axis.

175. The method of claim 174 wherein generating data to display the hilood flow information for the plurality of locations along the ultrasound beam axis comprises generating data corresponding to blood flow detected as having a blood flow velocity exceeding a velocity threshold,

176. The method of claim 175 wherein the velocity threshold is user programmable.

177. The method of claim 169 wherein generating data to display the blood flow information for the plurality of locations along the ultrasound beam axis comprises COMS 10 No: SMSI-00532124 Received by IP Australia: Time 17:28 Date (Y-M-cI) 2003-12-11 11/12 '03 THUL 17:23 FAX 61 2 9888 7600WARAK02WATERMARK [a 025 463 generating data to display color regions corresponding with the locations at which blood flow is detected having a detected Doppler signal power exceeding a power threshold.

178. The method of claim 177 wherein the power threshold is user programmable,

179. The method of claim 169, further comprising generating data to representing spectral graphical information indicating blood flow velocities at the selected one of the displayed locations. 182, The method of claim 169, futher comprising generating data to display locations along the ultrasound beam axis at which blood flow is not detected.

183. In a Doppler ultrasound system emitting ultrasound signals along an ultrasound beam axis and detecting echo signals resulting therefrom, a method for providing blood flow information of a subject to which the Doppler ultrasound system is applied, the method comprising: quantizing the detected echo signals to generate a plurality of digital sample values representative of the echo signals; generating quadrature vectors from the plurality of digital sample values; processing the quadrature vectors to calculate blood tlow data as a function of time for a plurality of locations along the ultrasound beam axis; and generating data from the blood flow data that is representative of blood flow detected along the ultrasound beam axis as a function of time, the data having a component associated with blood flow velocity at each of the locations for which data is generated. 183.1. The method of claim 183, further comprising processing the quadrature vectors to calculate detected Doppler signal power data as a function of time for the plurality of locations along the ultrasound beam axis, and generating data from the detected Doppler signal COMS IDNo: SMBI-00532124 Received by IP Australia: Time (I-tm) 17:28 Date 2003-12-11 11/12 '03 THU 17:23 FAX 61 2 9888 7600 WATERMARK o026 64 power data representative of varying the blood flow velocity component based on the detected Doppler signal power data.

185. The method of claim 183 wherein quantizing comprises quantizing the detected echo signals at four times the frequency of the emitted ultrasound signals.

186. The method of claim 185 wherein generating quadrature vectors from the plurality of digital sample values comprises: dividing the sample values into sets of four values, each set having first, second, third and fourth values; and for each set, subtracting the third from the first values to generate a real vector component of the quadrature vector and subtracting the fourth from the second values to generate an imaginary vector component of the quadrature vector.

187. The method of claim 183, further comprising calculating filter coefficients based on the rate at which the detected echo signals are quantized, and wherein processing the quadrature vectors to calculate blood flow data comprises: processing each quadrature vector using the filter coefficients to calculate filtered quadrature vector data representative of the quadrature vector having noise from outside a bandwidth of interest removed; calculating from the data for a plurality of quadrature vectors clutter cancelled vector data representative of the filtered quadrature vectors having contribution from stationary reflectors removed from the filtered quadrature vectors; and 187.1. The method of claim 187, further comprising calculating detected Doppler signal power for each of the first plurality of locations along an ultrasound beam axis from the clutter cancelled vector data. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 -II- 11/12 '03 THUL 17:23 FAX 61 2 9888 7600WAEAR j02 WATERMARK 10 027

188. The method of claim 183, fur-ther comprising processing the quadrature vectors to calculate a mean velocity for each of the plurality of locations along the ultrasound beam axis.

189. The method of claim 183, further comprising generating data representing spectral graphical information indicating blood flaw velocities at the selected one of the displayed locations.

198. A computer-readable medium having computer executable instructions for controlling digital processing circuitry in a Doppler ultrasound system to process detected ultrasound echo signals and provide blood flow information, by: controlling an analog-to-digital convertr (ADC) circuit to quantize the detected ultrasound echo signals to generate a plurality of digital sample values representative of the ultrasound echo signal; generating quadrature vectors from the plurality of digital sample values; processing the quadrature vectors to calculate blood flow data as a function of tine for a plurality of locations along the ultrasound beam axis; and processing the blood flow data to generate data that is representative of blood flow velocity as a function of time detected for the plurality of locations along the ultrasound beam axis, the blood flow data having a component at each of the plurality of locations indicative of blood flow velocity. 198.1. The computer readable medium of claim 198 wherein the computer extecutable instructions for processing the blood flow data comprises processing the quadrature vectors to calculate detected Doppler signal power data for the plurality of locations along the ultrasound beam axis and processing the blood flow data to generate data representing varying the component based on the detected Doppler signal power data. COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:24 FAX 61 2 9888 7600 WTRAK~ 2 WATERMARK [a 028 66

200. The computer readable medium of claim 198 wherein the computer executable instructions for controlling the ADC circuit comprises computer executable instructions for controlling the ADC circuit to quantize the detected echo signals at four times the frequency of the emnitted ultrasound signals. 201, The computer readable medium of claim 200 wherein the computer executable instructiors for generating quadrature vectors from the plurality of digital sample values comprises computer executable instructions for: dividing the sample values into sets of four values, each set having first, second, third and fourth values; and for each set, subtracting the third from the first values to generate a. real vector component of the quadrat=r vector and subtracting the fourth from the second values to generate an imaginary vector component of the quadrature vector.

202. Tlhe computer readable medium of claim 198, further comprising. computer executable instructions for calculating filter coefficients based on the rate at which the detected echo signals are quantized, and wherein the computer executable instructions for processing the quadrature vectors to calculate blood flow data comprises computer executable instructions for: processing the quadrature vectors using the filter coefficients to calculate filtered quadrature vector data representative of the quadrature vectors having noise from Outside a bandwidth of interest removed; and calculating clutter cancelled vector data representative of the filtered quadrature vector data having contribution from stationary reflectors removed from the filtered quadrature vector data. 202.1 The computer readable medium of claim 202, further comprising computer executable instructions for calculating the detected Doppler signal power as a function COMS ID No:SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THUl 17:24 FAX 61 2 9888 7600 WTRAKEjz WATERMARK [a 029 67 of time for the plurality of locations along an ultrasound beam axis from the clutter cancelled vector data,

203. The computer readable medium of claim 198, further comprising computer executable instructions for processing the quadrature vectors to calculate a mean velocity for the plurality of locations along the ultrasound beam axis. 204 The computer readable medium of claim 198, further comprising computer executable instructions for processing the blood flow data to display spectral graphical information indicating blood flow velocities at the selected one of the displayed locations. 205, The computer readable medium of claim 198, further comprising computer executable instructions for processing the blood flow data to display locations along the ultrasound beam axis at which blood flow is not detected.

206. The computer readable medium of claim 198 wherein the computer executable instructions for processing the blood flow data for display comprises computer executable instructions for processing the blood flow data to generate data representative of blood flow in a first direction and generate data representative of blood flow in a second direction.

207. The computer readable medium of claim 198 wherein the computer executable instructions for processing the blood flow data for display comprises computer executable instructions for processing the blood flow data to genera-te data corresponding with the locations at which blood flow having a blood flow velocity exceeding a velocity threshold.

208. The computer readable medium of claim 198 wherein the computer executable instructions for processing the blood -flow data for display comprises COMS ID No: 5MBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11 11/12 '03 THU 17:24 FAX 61 2 9888 7600 WATERMARK 12030 68 computer executable instructions for processing the blood flow data to generate data corresponding with the locations at which blood flow is detected having detected Doppler signal power exceeding a power threshold.-- COMS ID No: SMBI-00532124 Received by IP Australia: Time 17:28 Date 2003-12-11