CN1774646A - Heart wall strain imaging - Google Patents

Abstract

Ultrasound image processing system comprising means for acquiring ultrasound image data of the heart, means for forming a sequence of ultrasound images of the heart during a cardiac cycle and means for providing tissue velocity data of the heart wall, and further comprising means for estimating the time occurrence of a specific event related to heart strain for a point inside the heart wall. This system may comprise means for estimating the temporal variations of heart strain measured at a selected point inside the heart wall. This system may further comprise means for estimating the instants of occurrence of maximal and minimal variations of heart strain and their amplitudes from the measured temporal variations of heart strain at a selected point inside the heart wall and means for estimating the instants of temporal occurrences of the maximal and/or minimal variations of heart strain, along a line representing the heart wall.

Description

Heart wall strain imaging

Technical field

The present invention relates to a kind of image processing system, this image processing system is used to obtain the ultrasound image data of health heart, handle this view data to estimate the Tissue velocity in the heart wall tissue, and show have with cardiac cycle during the cardiac ultrasound images of the relevant information of heart wall displacement, this information is derived by heart wall tissue speed.The invention still further relates to the supersonic inspection device that a kind of and this image processing system combines.

The present invention is applied to the medical imaging field that cardiac muscle is checked especially.

Background technology

The ultrasonoscopy treatment technology that is called as tissue doppler imaging (TDI) is for conventionally known to one of skill in the art.The velocity of displacement that this TDI technology allows to measure patient body inner tissue in no wound mode is with further estimation organizational parameter, and shows the image of representing described speed in the coloud coding mode, shows conventional ultrasound intensity image simultaneously.

Known a kind of method of during cardiac cycle, measuring the arterial wall displacement amplitude from patent US 5,938,606.This method can show the arterial wall image and indicate the motion of arterial wall that the curve that is superimposed upon on the conventional ultrasound intensity image that moves through of this arterial wall is represented.This method may further comprise the steps: carry out arterial wall and cut apart to locate this arterial wall in the image of a sequence, image data processing is defined as the function of time with the amplitude with the arterial wall displacement, and the curve of drawing expression arterial wall displacement amplitude.This method also comprises uses the image sequence that shows artery by the superimposed curves of the function of time motion.

Summary of the invention

For artery, aAs cited patents provided, the information of the displacement amplitude of wall is easy to utilize, because artery is an elongated organ with longitudinal axis.The displacement of wall is only perpendicular to this axle, and in the direction conduction that influences this axle of lower edge of heart pulse rate.

Nowadays, for the heart with the wall that is formed by the muscle around the chambers of the heart, the motion of wall is very complicated.Can not compare with the arterial wall displacement by the heart wall displacement that heart pulse rate causes, can not represent as the arterial wall displacement.The complicacy of heart wall motion is because the following fact, i.e. the contraction of heart wall after bearing diastole during each cardiac cycle, and these are taken as contraction in the heart wall of muscle and the conduction of diastole is not isotropic.Instead, contraction of these in the heart wall and diastole appear to follow specific propagation law.In fact, say that arrhythmia cordis or myocardial damage can change or disturb the contraction/relaxation conduction from clinical point.Need a kind of not normal instrument of these specific conduction of studying.

The purpose of this invention is to provide a kind of image processing system, this image processing system has and shows the device provide the image of the temporal information of heart wall displacement conduction during cardiac cycle; And more specifically has a device that provides the temporal information of myocardial wall internal modification during cardiac cycle.These images are called as strain (strain) image.

A kind of image processing system with this device is required in claim 1.

Another object of the present invention provides a kind of like this image processing system, this system has the device of display image, and each internal point place that described image is given in myocardial wall during cardiac cycle is corresponding to the maximum strain of diastole zero hour with corresponding to the information that goes out now and the described minimum and maximum value of the minimum strain that shrinks the zero hour.This image processing system is required in the dependent claims.

The advantage of this image processing system is that described system makes because myocardial contraction/relaxation phenomenon that heart polarization caused is visual, and can represent the conduction of muscle response simultaneously.

The supersonic inspection device that a kind of and this image processing system combines is required in the dependent claims.

Description of drawings

In order to understand the present invention better, with reference to following schematic figures, wherein:

Fig. 1 is the ultrasonoscopy of heart left ventricle, wherein segmented line (ABC) expression left ventricular wall;

Fig. 2 illustrates speed (V) figure as time (t) function along the left ventricular wall segmented line (ABC) of Fig. 1 record by tissue doppler imaging (TDI) commercial measurement, transverse axis express time wherein, it has passed through the cardiac cycle of several successive, and Z-axis is represented segmented line (ABC);

Fig. 3 is the local train curve of measuring on the Chosen Point of segmented line (ABC), therefrom extract the strain maximal value (M1-M4) of four cardiac cycles and the time (t) that strain minimum value (m1-m4) is occurred, extract strain amplitude simultaneously, wherein the diastole that corresponds respectively to cardiac muscle of each maximal value of strain and each minimum value begins and shrinks beginning;

Fig. 4 is the ifm diagram of left ventricle, and wherein come out with color mark in the zone that presents its maximum collapse value in this particular moment during cardiac cycle; And the time reference that has wherein provided this incident in the corresponding position of ECG curve.

To the appearance (representing with black) that left ventricular wall maximum collapse among Fig. 1 was shown four cardiac cycles and the appearance (representing with white) of minimum of contraction, it is the function that is illustrated in the time (t) on the transverse axis to Fig. 5 along the segmented line (ABC) represented on Z-axis;

Fig. 6 is given in the curve that occurs the time (t) of maximum collapse on each point of segmented line (ABC) during a cardiac cycle;

Fig. 7 is the block diagram that schematically shows the ultrasonic device that combines with imaging system of the present invention;

Fig. 8 schematically shows a kind ofly to be used to obtain ultrasound data and to provide the heart strain information and the block diagram of the ultrasonic image-forming system of heart strain pattern.

Embodiment

A kind of image processing system that the echo that is provided by supersonic imaging apparatus is traced (echographic) signal that is used to handle is provided.This image processing system has the device that is used to obtain ultrasound data, is used for the view data processing and is used to carry out ultrasonic imaging.According to the present invention, this image processing system is used to carry out the measurement of heart wall strain.This imaging system has treating apparatus estimating locating the time that the minimum and maximum value of heart wall strain occurs for cardiac cycle every of heart wall, and the amplitude of heart wall strain at that time.The diastole that each maximal value of strain and each minimum value correspond respectively to cardiac muscle begins and shrinks beginning.This image processing system has the device that shows the image be called as strain pattern, and described image provides the temporal information of myocardial wall internal strain conduction during cardiac cycle.This imaging system shows the image that is given in the correct time information of each internal point place maximum distortion (the diastole zero hour) of myocardial wall and minimal deformation (shrinking the zero hour) appearance during cardiac cycle.These images are dynamic images, and it illustrates the conduction of the excited muscle response of cardiac muscle, as shown in Figure 4.

With reference to figure 8, ultrasonic examination system 50 comprises probe or scanner head 10 and display device 40.The operation of ultrasonic examination system relates to be arranged to probe 10 and the contact patients of study, to launch ultrasonic signal and to be received in the echo that the barrier that runs in the medium reflects by periodically exciting to heart of patient.Probe 10 can be made up of the ultrasonic transducer 12 that is assembled into phase battle array or linear array, bent battle array or other array.Probe can be placed on the outside or inner of the health of studying.The array of element of transducer is emission energy pulse or energy beam in health, and receives its pulse of returning from the energy of body interior structure reflection.These energy pulses or energy beam are coupled to ultrasonic system electronically.

The ultrasonic examination system that is connected to probe 10 comprises the emitter/receiver level 14 that is used to produce the excitation signal that is applied to probe 10.Probe transducers becomes these conversion of signals the ultrasonic arteries and veins train of signal of periodicity that provides with predetermined repetition frequency.The acoustic signal that returns is received by emitter/receiver level 14 and combination forms to restraint in 16.The emitter/receiver level also provides control signal to control probe 10, pulse signal and velocity estimation stages.

At the emission mode of emitter/receiver level 14, along excitation line scanning direction patient's heart.At receiving mode, consider the amplitude of the echo of the barrier reflection that conduction time in the medium and the excitation line of being considered by the edge run into, form the image of each excitation line.In the emission mode of emitter/receiver level 14, every excitation line of probe 10 can provide the acoustics high-frequency signal, and it can form the sequence that level forms intensity image by image.This intensity image sequence is called as ultrasonic grayscale image sequence, and it shows with the 2D image mode, comprises the such a image of the sector diagram that resembles Fig. 1.

Supersonic inspection device also comprises the device of permission with tissue doppler imaging's pattern (TDI) operation of coloud coding, and it can determine the speed in patient's organ-tissue.Tissue doppler imaging is the technology that a kind of estimation projects the Tissue velocity vector components on the acoustic beam.The displacement of structures of interest is to cause phase shift by organizing on the backward scattered continuous high frequency ultrasound echo of motion.I is passed through in these phase shifts, and Q demodulation stae 18 separates level 30 to be handled with tissue/flow, so that the local velocity of the tissue that estimation is checked in histokinesis's estimation level 31.

Then, tissue velocity estimation stage 31 is handled the doppler echo signal that sent by level 30 to obtain Doppler's shift characteristics, such as the frequency corresponding with speed.Doppler processor 31 is handled the echoed signal that receives from the same space position of heart and is determined Doppler phase shift or frequency displacement.Doppler processor 31 can be by Fast Fourier Transform (FFT) (FFT) or the displacement of autocorrelation operation estimating Doppler.Doppler's estimator 31 is preferred to adopt two-dimensional autocorrelations, and it carries out auto-correlation and produces accurate, the high-resolution Doppler estimation that is shifted on time and space.

Tissue velocity processor stage 32 is handled tissue signal, and if desired, it can comprise that also scan conversion 33 is to convert the required image pattern to.In level 32, the signal colour is depicted as the value of color zone.The cromogram of Doppler signal utilizes video processor 34 can be covered on the gray level image that is provided by B schema processor 20 then.The colour of indication speed is added on the gray level image of intensity, thereby forms the tissue velocity image sequence of coloud coding.The tissue velocity sequence of this coloud coding can be stored in the storer.

The signal Processing of carrying out in TDI is similar to the color Doppler imaging system blood flow is carried out the signal Processing that imaging is adopted.Yet, need make amendment to the setting of ultrasonic system, because Tissue velocity is lower than blood flow velocity, and the tissue signal amplitude is than blood signal amplitude height.These modifications comprise the shortening entire length, reduce pulse repetition rate (PRF) and make wall portion wave filter (if present) ineffective.

According to the present invention, this TDI technology is used for measuring the speed of patient's heart wall.The operation of heart wall velocity survey comprises the heart wall motion estimation.Motion by the observed biological structure such as tissue of TDI is to be produced by the interaction between internal mechanical power (angiosthenia, myocardial contraction/diastole power) and the tissue (cardiac muscle).Adopt the TDI sequence just might extract special physiological parameters, but these parameter imagings and be used to measure the biomechanics function of heart wall.According to the present invention, adopt the TDI image from calculating heart wall strain along the space derivative on the supersonic beam of space, as described below.

With reference now to Fig. 1,, the B mode sector image of its expression cardiac muscle, wherein the mensuration of myocardium strain rate at first comprises heart wall segmentation.For example adopt edge detecting technology from B mode image sequence, to extract the heart wall edge, thereby the segmented line SL of expression heart wall position is provided.The position of wall segmentation line SL is added on the B mode image of Fig. 1.

Still,, must on a complete cardiac cycle, observe the heart wall activity for estimating the speed of tissue perpendicular to heart wall with reference to figure 1.Therefore, must form the image sequence that adds up to N that covers the time interval that equals a cardiac cycle at least, these images are in each n generation constantly, and N is the number greater than 1.In addition, must discern for the tissue velocity image sequence with for cardiac cycle is the time mark that has.Like this, just can observe heart tissue according to the out of phase of cardiac cycle.

On the TDI datum plane, draw the position of wall segmented line SL then.Based on the position of motor tissue, carry out local time's integral Calculation of TDI velocity amplitude.This calculating provides as whole cardiac cycle length function with as the wall shift value of function of position.

If z is any coordinate along on the acoustic beam and institute inspection heart wall inside.The displacement of this point is provided by following formula:

$M(z,t)=\underset{t_0}{\overset{t}{\∫}}V(z,u)\mathrm{du}---\left(1\right)$

Wherein (z u) is the speed that is provided by TDI to V, and t ₀It is zero hour of cardiac cycle for example.

TDI speed along segmented line SL among Fig. 1 is measured with time t function, as shown in Figure 2.Speed is represented along Z-axis, and time t represents along transverse axis.Some A among Fig. 2, B, C are corresponding to some A, B, C among Fig. 1.Fig. 2 relates to the duration of about four cardiac cycle.White portion is at a high speed corresponding, and the corresponding low speed of dark part.

Now, the compressibility ability organized is represented in strain.Suppose that along two close positions of acoustic beam be z and z+dz, then in the inspection tissue, strain S (z t) equals:

$S(z,t)=\frac{M(z+\mathrm{\δz},t)-M(z,t)}{\mathrm{\δz}}=\frac{\mathrm{\δM}(z,t)}{\mathrm{\δz}}---\left(2\right)$

Rate of strain is represented the speed of tissue compression or expansion.Rate of strain is by to give a definition:

$\mathrm{SR}(z,t)=\frac{\mathrm{\δS}(z,t)}{\mathrm{\δt}}---\left(3\right)$

Drawing rate of strain by (1) and (2) can directly derive from the TDI velocity information:

$\mathrm{SR}(z,t)=\frac{\mathrm{\δV}(z,t)}{\mathrm{\δz}}---\left(4\right)$

Can directly derive strain in conjunction with equation (3) and (4) from the TDI velocity information:

$S(z,t)=\underset{t_0}{\overset{t}{\∫}}\frac{\mathrm{\δV}(z,u)}{\mathrm{\δz}}\mathrm{du}---\left(5\right)$

After this adopt equation (5) so that estimate heart wall strain.

Measure myocardial wall speed from the tissue Doppler velocity image of the cardiac muscle that forms as shown in Figure 2.Then, the estimating speed gradient, just rate of strain is revised with supersonic beam angle function certificate.The calculating of this correction is called as spatial gradient procedure.Because myocardial wall is the fact that moves with respect to current supersonic beam, so these corrections are necessary.Then, make up gradient image and at each point of wall to Grad by the time integration.

With reference to figure 3, according to the present invention, equation (5) is used to estimate by the Chosen Point on the segmented line SL of some A, a B, C, i.e. the change curve of the function of time of the strain amplitude measured of variable Z chosen place.For the every bit of velocity image, extract the time curve of distortion and be referred to as strain curve.In example shown in Figure 3, this curve has provided the time t of strain amplitude peak M1 in four cardiac cycles, M2, M3, M4 and strain minimum radius m1, m2, m3, m4 appearance, and provided these strain amplitude values constantly, wherein each maximal value of strain and each minimum value correspond respectively to myocardial relaxation and begin and shrink beginning.Estimated to be used to make up the minimum and maximum amplitude of strain curve and the time of appearance thereof for each the point-of-interest storage on heart wall and particularly the segmented line SL.

With reference to figure 4, the information architecture that is provided by the strain curve of Fig. 3 shows corresponding to the contraction starting position of minimum strain with corresponding to the dynamic sequence of the diastole starting position of maximum strain.Consider such as ultrasonic image sequence shown in Figure 1 now.When the every bit of described picture centre flesh wall during corresponding to maximum collapse value or minimum of contraction value, described point receives the color of stack separately.Because the position of maximum or minimum strain value changes in time, so these images form contraction/relaxation conducting image sequence.Amplitude peak is expressed as for example red, and minimum radius can be expressed as green.Image sequence such as image shown in Figure 4 allows to manifest a kind of mode, and according to this mode, an incident for example corresponding to the maximum or the minimum strain of maximum or minimum of contraction, is conducted in the represented space of cardiac muscle and as the function of time.These event tables reveal defers to specific rule.

For describing these relevant expressions with this in the key diagram 4, the white marking part is corresponding to the part that maximum strain (diastole begins) is located occurs at moment t.The present invention allows to utilize these specific excited propagation law of image studies of Fig. 4, Fig. 5 and Fig. 6, and it is relevant with the maximum collapse conduction.Same research can be used for minimum of contraction propagation.

With reference to figure 5, it makes up an image again, this image is for four cardiac cycles, on the segmented line SL that passes through ABC that launches along Z-axis, provide the maximum strain (representing) that occurs in the left ventricular wall of Fig. 1 and the minimum strain (representing) of appearance, the function that appears as the time of on transverse axis, representing (t) of these strains with white with black.This image can manifest the response to heart pulse rate, and can study during cardiac cycle strain is according to which kind of mode to conduct in the heart wall.

With reference to figure 6, by the value that image calculated of design of graphics 5, the contraction that begins corresponding to diastole now is peaked to be gone out to be indicated on along on the Z-axis of time t now, and the point of segmented line SL is indicated on the transverse axis.Therefore, the curve of Fig. 6 provides the moment that relation begins to occur among every of the SL during cardiac cycle.The instantaneous slope of these curves provides conduction orientation by the symbol of slope, and provides conduction of velocity by the amplitude of slope.For example, conduction of velocity can be measured with mm/s.Experiment shows that the curve that obtains is very similar on several cardiac cycles.Equal research can provide the moment that occurs corresponding to the contraction minimum value of shrinking beginning along on the Z-axis of time t, and the point of segmented line SL on transverse axis=not shown.

Fig. 7 illustrates the figure according to supersonic inspection device of the present invention that combines with the system 50 of Fig. 8.This equipment comprises the probe 10 of the Digital Image Data that is used to obtain an image sequence, and the Vltrasonic device 53 that is used to handle these data according to the present invention.Particularly, data processing equipment 53 has calculation element and the memory storage that calculates and make up aforesaid image.Also can realize a kind ofly having preprogrammed instruction and calculating and the computer program of design of graphics picture to finish.This ultrasonic calculation element can be applicable to the medical image stored, for example is used to estimate medical parameter.This system provides the view data of processing to display device and/or memory storage.Display device 40 can be a screen.Memory storage can be the storer of system 53.Described memory storage also can be chosen as external memory.This image observation system 53 can comprise the computing machine of suitable programming, or has the application specific processor of the circuit arrangement such as LUT, storer, wave filter, logical operator, and these circuit arrangements are provided to carry out according to calculating of the present invention.System 53 also can comprise keyboard 55 and mouse 56.Can on screen, be provided with the icon that starts by click, perhaps can specific button be set in system, think that the user sets up control device 41, thereby at the treating apparatus of the choice phase start-up system of calculating.This medical observation system 50 can be bonded in the supersonic inspection device.This medical examination device can comprise patient lie thereon bed or be used to make patient's other parts with respect to the equipment location.The view data that is produced by supersonic inspection device is fed to medical observation system 50.

Claims (11)

1. ultrasonoscopy disposal system, the device that comprises the ultrasound image data that is used to obtain heart, be used for during cardiac cycle, forming the device of the ultrasonic image sequence of heart, and the device that is used to provide the Tissue velocity data of heart wall, and the device that also comprises the time of occurrence that is used to estimate particular event, this particular event is with relevant corresponding to the heart contraction/diastole of the minimum/maximum strain of any in the heart wall.

2. the system as claimed in claim 1 comprises the sectioning of the position that is used to estimate heart wall point selected on the segmented line of heart wall.

3. as the described system in one of claim 1 or 2, comprise the device that time of the heart strain that is used to estimate that the Chosen Point place is measured in heart wall changes.

4. system as claimed in claim 3 comprises that the time that is used for the basis heart strain that the Chosen Point place is measured in heart wall changes the device in the moment of the minimum and maximum variation appearance of estimating the heart strain.

5. as the described system in one of claim 3 or 4, comprise that the time that is used for the basis heart strain that the Chosen Point place is measured in heart wall changes the device of the amplitude of the minimum and maximum variation of estimating the heart strain.

6. system as claimed in claim 3 comprises that the time that is used for the basis heart strain that the Chosen Point place is measured in heart wall changes the device that now and their amplitude of the minimum and maximum variation of estimating the heart strain.

7. system as claimed in claim 6 comprises the imaging device that is used to make up dynamic sequence, and this dynamic sequence shows position that the contraction corresponding to minimum strain begins and the position that begins corresponding to the diastole of maximum strain (strain maximum).

8. as described system one of in the claim 3 to 7, comprise the device of image that is used for making up the time of occurrence of the maximum of heart strain and/or minimum change along the line of expression heart wall.

9. as described system one of in the claim 3 to 8, comprise being used for to estimating the maximum of heart strain and/or the device that goes out now of minimum radius along the Chosen Point on the line of expression heart wall.

10. supersonic inspection device comprises the ultrasonic probe of the element of transducer of the image sequence that is used to obtain heart, as described system one of in the claim 1 to 9, and the display device that is used to show ultrasonoscopy.

11. a program product has one group of instruction that is used for finishing as the function of the device of the described system of one of claim 1 to 9.

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