DETECTION OF TISSUE ABNORMALITIES USING ULTRASONIC SCANNING
RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Application Serial No. 60/358,103, filed February 15, 2002, entitled "System for Improved Detection of Tissue Abnormalities using Palpation and Ultrasonic Scanning of Subcutaneous Tissues and Organs." [0002] This application is a continuation-in-part of U.S. Application Serial
No. 09/890,501, filed August 1, 2001, entitled "Apparatus and Method for Detecting Anomalies in Human Tissue," which is the national stage of International Application No. PCT/US00/02341, filed January 29, 2000, with publication no. WO 00/44281, which claims benefit of U.S. Application Serial No. 09/241,193, filed February 1, 1999, which is a continuation-in-part of U.S. Application Serial No. 08/957,648, filed October 24, 1997, now U.S. Patent No. 6,192,143.
[0003] This application is a continuation-in-part of International Application No. PCT/USOl/31572, filed October 9, 2001, with publication no. WO 02/39891 Al, entitled "A Dynamic Health Metric Reporting Method and System," which claims benefit of U.S. P / rovisional Application Serial No. 60/238,349, filed October 6, 2000, entitled "A Dynamic Health Metric Reporting System."
[0004] The above-noted related applications (and patent) are each incorporated in their entirety by this reference.
FIELD OF THE INVENTION [0005] The present invention relates to methods and apparatus for detecting anomalies in bodily organs and tissue, and more particularly to medical imaging for such detection. The present invention includes tissue scanning and palpation, tissue anomaly detection, and three-dimensional mapping, objectively generated, that identifies pre-selected characteristics of body tissue, such as density, for comparable tissue examination against subsequent images of similar body tissue.
BACKGROUND OF THE INVENTION
[0006] There is a constant need for improved tissue anomaly detection. Recent improvements in ultrasound technology have produced ultrasound transducers
and associated computer systems for medical use in detecting abnormalities in or normal structural features of organs and tissues below the surface of the skin. For example, improved ultrasound systems have recently been used to determine whether a breast tumor greater than 1 cm in diameter is solid or cystic (hollow). In addition, ultrasound transducers are now developed for potentially higher resolution and sensitivity; however, their range of depth is still limited to about 15-20 mm.
[0007] There are medical applications where it would be useful to generate ultrasound images illustrating characteristics of tissues and organs more than 15 mm below the epidermis (i.e., exceeding a typical range of depth of an ultrasound transducer probe). One example is breast tissue, where tissue underlying the skin is soft and compressible, thereby facilitating such depth of image. Accordingly, a method and system capable of using a single ultrasound transducer probe to create maps at multiple, overlapping depths, and to generate a resulting image interpreted by fractal analysis, or other software such as that used for M-scan ultrasound, to match the overlapping topographies, would be advantageous to early anomaly detection.
[0008] Important to the generation of such an image would be an ability to know precisely, in three-dimensional space, a location of an ultrasound probe at a surface of the skin (before tissue compression), and then a precise subsequent positioning, in a dimension of depth relative to the surface of the skin, of a location of the probe during scanning, to facilitate a matching of topographies during overlap when generating the image. Further, precise control and tracking of the probe in three-dimensional space would provide for later image generation of the exact portion of the organ or tissue, for comparative examination.
SUMMARY OF THE INVENTION [0009] The present invention is an apparatus and method for early detection of small anomalies in bodily organ and tissue using ultrasound technology, or using a combination of ultrasonic scanning and mechanical palpation. The present invention generates acoustic tissue images providing both high resolution (e.g., 0.3 mm) and depths below 15 mm, serving to provide a systematic and operator-independent ultrasonic organ and tissue exam. Accordingly, the images generated by the present invention provide an examination tool for objectively tracking pre-selected characteristics of body tissue over time, facilitating early detection of even the smallest of tissue anomalies. Aspects of the present invention thereby enable use of
ultrasound as a screening tool, permitting a centralized reading and interpretation of resulting images at a site remote from the examination site. s
[0010] Objective multi-dimensional maps, with or without color, are generated using ultrasound by systematically scanning a desired region of organ or tissue in a grid, and at various depths within the grid, to develop an image that is generated objectively (without operator bias) so that it may be interpreted and compared objectively. Objective ultrasonic scanning in accordance with the present invention is especially useful for analyzing breast density, which is presently performed by human touch during a clinical breast exam. Further, objective ultrasonic tliree-dimensional imaging is also useful for monitoring tumors within the abdominal cavity, since the abdominal skin can generally be depressed until the abdominal wall is close to the internal organ or tumor(s) of interest.
[0011] one aspect of the present invention, a method for detecting anomalies in bodily organs and/or tissue ("body tissue") includes positioning a probe into acoustic contact with a desired region of body tissue, performing an ultrasound scan using the probe, advancing the probe a pre-determined depth into the body tissue, performing another ultrasound scan using the probe, and integrating data from the ultrasound scans in a dimension of depth, to generate an image identifying one or more pre-selected characteristics of body tissue. [0012] Integrating data from the ultrasound scans could be performed by matching overlapping topographies in the dimension of depth. The image could identify the one or more pre-selected characteristics of body tissue at depths greater than a depth of view capability of the probe. The depth of view capability could refer to the rated range of view according to probe specification, or an actual range of view according to a scan of the subject tissue. The body tissue could be breast tissue, the pre-selected characteristic of body tissue could be density, the probe could be positioned and advanced robotically or by human operator, and the pre-determined depth of probe advancement could be a pre-established percentage of the rated depth (range) of view of the probe, or a pre-established percentage of the actual range of view.
[0013] In another aspect of the present invention, the method for detecting anomalies in bodily organs and/or tissue ("body tissue") includes outlining a desired region of body tissue, generating characteristic data for the desired region of body tissue outlined, and generating scanning methodology based upon the characteristic
data, and based upon operating specification data of an ultrasound probe. Then, the probe is positioned about the desired region of body tissue, and ultrasound scans are intermittently taken in accordance with the scanning methodology generated. The scanning data is then integrated, with matching topographies overlapped, to generate an image identifying one or more pre-selected characteristics of the body tissue.
[0014] For the above aspects of the present invention, the integration of overlapping topographies, with generation of resulting images, could occur in one, two, or three dimensions. Further, the above aspects could each further include a monitoring of resistance to probe motion, where probe motion would cease in a certain direction when a pre-selected resistance to probe motion in the certain direction is reached (detected).
[0015] another aspect of the present invention, the method for detecting anomalies in bodily organs and/or tissue ("body tissue") includes positioning a probe into acoustic contact with a desired region of body tissue, recording position characteristics of the probe, performing an ultrasound scan using the probe, advancing the probe a pre-determined depth into the body tissue, recording position characteristics of the probe, and performing another ultrasound scan using the probe. Recording, scanning and advancement is repeated at the desired region of body tissue until a pre-selected resistance to probe motion is detected, or until a desired depth into the body tissue is reached, upon which probe advancement into the body tissue ceases and a final ultrasound scan is performed at the desired region of body tissue. Then, the probe is retracted a distance indicative of pre-established criteria, and the probe is positioned at a new location of acoustic contact with the body tissue, where recording, scanning and advancement is repeated until a pre-selected resistance to probe motion is detected, or until a desired depth into the body tissue is reached, and a final scan is performed at this location. The above is repeated for all locations within the desired region of interest, and the scanning data is then integrated, and overlapping topographies matched, to generate an image identifying pre-selected characteristics of body tissue. This aspect of the invention could further include preliminarily outlining the desired region of body tissue, generating characteristic data for the desired region outlined, and generating scanning methodology based upon the characteristic data and upon operating specification data of the ultrasound probe. The scanning methodology would then be used to direct probe positioning, advancement, and the taking of ultrasound scans.
[0016] h another aspect of the present invention, an apparatus for detecting anomalies in bodily organs and/or tissue ("body tissue") is provided, and includes an ultrasound probe to scan a desired region of body tissue at a plurality of depths, a positioning device to position the probe at the plurality of depths; and a computer- readable medium that configures a computer system to integrate data from the ultrasound scans, to match overlapping topographies in at least a dimension of depth, and to generate an image identifying one or more pre-selected characteristics of body tissue. The apparatus could further include a position tracking system to monitor the position of the probe in each of three dimensions, and/or to further assist in directing the positioning of the probe. The positioning device could be a rpbotic positioning device, or could be a hand-held device adapted for a human operator.
[0017] In another aspect of the present invention, the apparatus for detecting anomalies in bodily organs and/or tissue ("body tissue") includes an ultrasound probe and system to scan a desired region of body tissue, a position tracking system to outline the desired region of body tissue, a computer-readable medium that configures a computer system to generate characteristic data for the desired region of body tissue outlined, and to generate and maintain the scanning methodology. The apparatus also includes a positioning device for manipulating the ultrasound probe about the desired region of body tissue, and a computer-readable medium configuring a computer to direct the scanning in accordance with the scanning methodology generated, to integrate data from the ultrasound scans, to match overlapping topographies, and to generate an image identifying one or more pre-selected characteristics of body tissue. The apparatus could further include a memory device to record data obtained and generated, a strain gauge located in communication with the probe to monitor a resistance to probe motion, and/or a transmitter to signal and/or direct the positioning device when a pre-selected resistance to probe motion is detected. The positioning device could again be robotic, or a hand-held device adapted for a human operator.
[0018] Aspects of the present invention could also further include incorporation of palpation data for the subject organ or tissue, where the body tissue is palpated with a palpation probe, then a distance traveled by, or a velocity of motion of, or a time in motion of, the palpation probe is detected, and one or more preselected characteristics of body tissue based upon at least one of the distance traveled by, the velocity of motion of, or a time in motion of, the palpation probe is determined. An image could then be generated, the image identifying the one or more
pre-selected characteristics of body tissue based upon the palpation data, whereby the present invention provides two images for anomaly detection, one that acoustically identifies the one or more pre-selected characteristics of body tissue based upon the ultrasound scans, and another that mechanically identifies the one or more pre- selected characteristics of body tissue based upon the palpations. In this aspect, the apparatus for further include at least one palpation probe to palpate the desired region, at least one detector to detect a distance traveled by, or a velocity of motion of, or a time of motion of, the at least one palpation probe, and a computer-readable medium to configure a computer system to determine the one or more pre-selected characteristics of body tissue.
[0019] Aspects of the present invention could also be used and incorporated into a dynamic health metric reporting system, where the reporting system collects and stores examination data (acoustic or mechanical) for each of multiple examinations of subject bodies (regions of bodily organs or tissue of interest). The examination data from two or more selected examination dates is compared, and differences determined, for a specific subject body. The differences between two or more examination dates are characterized and stored in a database. A report is generated that details the differences in the examination data to assist in predicting a likely course of health for the subject body.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention is a method and system for detecting anomalies in bodily organs and tissue, and for generating images of the bodily organs and tissue for use in detecting such anomalies, and for use in detecting anomalies by comparing the image to similar images generated at different points in time. For purposes herein, bodily organs and tissue refer to any organs and tissue, whether living or dead, and whether plant or animal, as the present invention is equally applicable to human, veterinary, and/or horticultural uses. For simplicity, the term "body tissue", or "tissue", may be used in the specification, with the understanding that this term is not limiting, and that any bodily organ or tissue is contemplated. While use directed to all organs and tissue is contemplated, the present invention may be particularly useful for organs and tissue accessible by surface examination, and for organs and tissue uniquely deformable, such as breast tissue. The present invention also contemplates objective image generation of the bodily organs and tissue, thereby removing operator
sampling bias when choosing an image or volume to scan, and examination that is precise and more readily reproducible, thereby facilitating comparative analysis over time.
[0021] In a general embodiment, the present invention is directed to using ultrasound scanning as a screening tool for early detection of bodily organ and tissue anomalies, by using resulting ultrasonic scanning data to generate images of preselected organ and tissue characteristics in three-dimensions, where at least a dimension of depth displayed in the image includes data from two or more scans integrated together, with matching topographies overlapped. The dimension of depth displayed in the image could, therefore, exceed a range of depth of view of a typical high resolution ultrasound probe, or of any ultrasound probe, or where a depth displayed exceeds a tissue transparency evident from a single surface scan of non- deformed tissue. Generally, the method entails positioning a probe into acoustic contact with body tissue of interest and performing an ultrasound scan using the probe. Next, the probe is advanced a pre-determined depth into the body tissue and another ultrasound scan is performed. After a desired number of scans are taken, data from the scans is integrated, and matching topographies are overlapped in at least a dimension of depth, to generate a map identifying one or more pre-selected characteristics of body tissue. [0022] The general method described above could be repeated at various other surface locations of body tissue, with data appropriately integrated, and overlapping topographies matched in one, two, or three-dimensions, to generate an image, perhaps in color, characterizing and identifying the one or more pre-selected characteristics of body tissue in the one, two, or three-dimensions. Data from the scans could be interpreted by fractal analysis, or other software such as that used for
M-scan ultrasound, to match the overlapping topographies. The objective generation of the image, as described above, lends itself to comparative evaluation relative to similarly generated images of the body tissue of interest performed at different points in time. [0023] Suitable probes and for the present invention could be obtained from
Cortex Technology of Denmark. Ten MHz through thirty MHz probes are available and are sufficient, as are either linear scanning transducer heads or sector scanning transducer heads. Alternatively, the Sonoline® Elegra ultrasound platform, by
Siemens Medical Systems, Inc., could be adapted to the present invention.
[0024] Probe positioning and advancement could be performed by an operator, or performed robotically. Each presents particular advantages and/or variations in features and performance. If robotic probe positioning is desired, a robotic positioning device satisfying present invention requirements is disclosed in U.S. Patent 6,192,143, the device therein referred to as the UltraTouch Palpagraph, and incorporated herein by reference. Alternatively, a suitable robot would also be the Motoman® UPJ, by Motoman Inc., of West Carrollton, Ohio, which has .03 mm repeatability, a personal computer based controller, and interface capability with an external force sensor. Alternatively, any robotic positioning device may be used having position capability within about 0.1 mm to 1.5 mm (preferably 0.2 mm to 0.6 mm) in three-dimensional space.
[0025] Integrating the scanning data, and matching overlapping topographies, could be performed using existing three-dimensional rendering techniques. For the present invention, these techniques integrate and smooth the data from one scan location to the next, in one, two, or three-dimensions. To minimize an amount of data in need of integration, thereby expediting image generation, while still ensuring high image resolution, the locations of probe placement and the extent of probe advancement into body tissue between ultrasonic scans are each efficiently predetermined based upon a consideration of probe operating specifications. Spatial relationships between locations of probe placement, and an amount of probe advancement between scans, will each be maximized (to minimize an overall amount of data) to an extent not sacrificing the operating capabilities of the probe. Alternatively, tissue transparency could be tested prior to determining the extent of probe advancement between scans, to identify a depth of acceptable resolution. Then, a pre-determined percentage of that depth is selected as the extent of probe advancement between scans in an effort to minimize an amount of data in need of integration, while still ensuring high image resolution.
[0026] The general embodiment could further include a monitoring of resistance, or return pressure, exerted by the body tissue on the advancing probe. After the probe is positioned into acoustic contact with the body tissue, and ultrasonic scan performed, the probe is advanced into the body tissue a pre-determined depth and another ultrasound scan is taken. Probe advancement continues in this way, with further scans taken, until enough data is acquired for a desired total depth of body tissue. If, during this probe advancement process, a pre-selected resistance, or return
pressure, is reached (detected), probe advancement will cease, and another ultrasound scan taken. The pre-selected resistance, or return pressure, is detected (sensed), and/or signaled, by a suitable load sensor placed in communication with the probe. The load sensor could be a strain gauge. The pre-selected resistance could be a force approximately between 150 grams and 1 kilogram.
[0027] The general embodiment could further include the step of preliminarily outlining, or mapping, of a region of body tissue desired, to facilitate a systematic and objective plan to acquire scanning data to generate images of the region, the systematic plan accommodating comparative examination of the image with other images of the region generated at other times. A digital photograph could be taken, to provide a field of view for examination, to guide probe positioning, and to provide for future probe positioning in subsequent examinations. If digital photographs are employed for outlining the region of interest, a photographic mapping device satisfying present invention requirements is disclosed in U.S. Patent 6,192,143, the device therein referred to as the UltraTouch Palpagraph, and incorporated herein by reference.
[0028] Alternatively, a suitable real-time motion tracking system adaptable to the present invention is pciBIRD™, provided by Ascension Technology Corp., of Burlington, Vermont. Using 8 mm probes, pciBLRD™ has a static accuracy of 1.4 mm RMS, a resolution of 0.5 mm, and an orientation resolution of 0.1 degrees at 30.5 cm distance. Alternatively, a three-dimensional position, or motion, tracking device, capable of simultaneous tracking of one or more sensors in three-dimensional space, could be used for tissue region mapping prior to ultrasonic scanning. The position, or motion, tracking is preferably performed in real-time, preferably includes orientation tracking, and is preferably compatible with a standard personal computer. With one sensor of the position tracking device placed in communication with the probe, probe positioning and advancement can be precisely performed, either robotically or by operator, and systematically recorded, to facilitate the acquisition of adequate scan data, and to minimize an amount of scans necessary to acquire the adequate scan data. [0029] The position tracking device could further be used to preliminarily establish one or more reference points with respect to the body, or patient, to continually monitor probe position and orientation with respect to the patient, thereby ensuring precise performance of probe positioning and advancement while compensating for patient movement during examination, and to preserve positional
mapping of the region of interest from exam to exam in relation to the patient's own body, in addition to three-dimensional positioning in absolute space.
[0030] The one or more reference points could be established on a patient backdrop, patient table, a patient positioning device, or on pre-selected locations of the body tissue under examination. If established on the body tissue, typical locations could be in the vicinity of bony structures, such as the sternoclavicular notch, or the lower sternocostal notch, or acromial protuberances (for breast examination). If established on a patient positioning device, one or more sensors could be placed or attached in pockets of, or in other previously identified positions of, a garment used to ensure consistent positioning of the body tissue. The garment could be constructed of a material facilitating acoustic contact with the probe. Or, the garment could be saturated with ultrasound coupling gel. Or, the garment could simply provide support for the body tissue subject to examination, preventing tissue movement during probe positioning and advancement. For example, a bra, with a pocket (perhaps located in the sternal area), could be used if breasts are the body tissue of interest.
[0031] The general embodiment could further include use of an ultrasound probe in conjunction with a mechanical palpation head, such as that disclosed in U.S. Patent 6,192,143 (the UltraTouch Palpagraph). The palpation head could be located in communication with the ultrasound probe, or the ultrasound probe could serve as the palpation head. Performing ultrasonic scanning in conjunction with mechanical palpation, the mechanical palpation as described in U.S. Patent 6,192,143, provides the advantage of generating simultaneous images of both acoustic density (revealed by ultrasound reflections) and mechanical density (from palpation detenninations). Because palpation by hand is a first modality for detection of breast cancer more than 70% of the time, and because ultrasound is so frequently used as a confirmatory diagnostic modality for lumps palpated by hand, a combination of ultrasound technology with mechanical palpation in one diagnostic exam will save time and improve diagnostic precision.
[0032] The various embodiments described above provide a mechanism making ultrasound tissue examination systematic, with objective generation of images identifying tissue characteristics, thereby permitting a centralized reading and interpretation of the images at a site remote to that of the examination site, and permitting a comparison of images of similar regions of interest taken at different points in time. A comparison of two or more images of selected tissue characteristics
for a single region of interest, with data collected at two or more points in time, provides opportunity for a further recordation, study, and reporting of the collected data, thereby improving the utility of diagnostic technology in the practice of medicine. [0033] Accordingly, scanning and/or palpation data collected and integrated into images identifying characteristics of body tissue, in accordance with methods and systems of the present invention, can be incorporated into a dynamic health metric reporting method and system, such as that disclosed in international application serial no. PCT/US01/31572, publication no. WO 02/39891 Al, which is incorporated herein by reference.
[0034] When adopting a dynamic health metric reporting method and system to one or more of the above embodiments of the present invention, the reporting system collects and stores examination data for each of multiple examinations of subject bodies (regions of bodily organs or tissue of interest). The examination data from two or more selected examination dates is compared, and differences determined, for a specific subject body. The differences between two or more examination dates are characterized and stored in a database. A report is generated that details the differences in the examination data to assist in predicting a likely course of health for the subject body. [0035] Alternatively, the system collects and stores examination data for each of multiple examinations of subject bodies. The examination data from two or more selected examination dates is compared for a specific subject body, differences are determined and one dynamic metric is created for the subject body, and stored in a database, for each pair of examination dates compared. One or more dynamic metrics for the subject body are compared with dynamic metrics for a relevant comparison population of similarly situated subject bodies in the database and reports are generated detailing the similarities and differences in the dynamic metrics for the subject body with the dynamic metrics of similarly situated subject bodies to assist in predicting a likely course of health for the subject body. An exemplary embodiment of the present invention
[0036] By way of example, a robotically controlled ultrasound scanning system according to the present invention operates as follows: first, one or more reference points are established on a patient backdrop, table, or patient positioning device, or on pre-selected locations of body tissue under examination. The reference
points are established by placing one or more sensors of a position tracking system in one or more of the above-referenced locations. Another sensor of the position tracking system is placed in communication with the ultrasound probe.
[0037] A region (area or volume) of the body tissue of interest is outlined using the position tracking sensor located in communication with the ultrasound probe. Characteristic data for the region of the body tissue outlined is generated and stored. The characteristic data can include a determination of the area, volume, and/or location of the region outlined in two or three-dimensions relative to the reference points established, or relative to absolute space. [0038] Software is then used to generate a scanning methodology based upon the characteristic data, and/or the operating specifications of the probe. The scanning methodology can include grid points, each grid point defined in a "x" and "y" dimension relative to the established reference point(s) or absolute space, each grid point having one or more associated scan points, each scan point defined in a "z" dimension relative to the associated grid point and/or the established reference point(s). The "x" and "y" dimension, as used in this example embodiment, lie in a plane parallel to a plane defining the patient backdrop, table, or patient positioning device, or parallel to a plane outlining generally the region of body tissue under examination. The "z" dimension is perpendicular to the plane, generally representing a depth into or out of the body tissue. Accordingly, the scanning methodology is established in three-dimensions to appropriately acquire data adequate to generate a three-dimensional image of the region of tissue outlined, and at a desired depth of view, even if the depth desired exceeds a range of view capability of the probe and/or exceeds a single scan transparency of the body tissue (i.e., a single, surface scan taken without tissue deformation).
[0039] This embodiment of the present invention contemplates minimizing the amount of data in need of integration, to expedite image generation, and contemplates doing so without sacrificing image resolution. Accordingly, the scanning methodology is generated through consideration of the operational specifications of the probe. For example, a diameter of the ultrasound probe would determine the grid size and resolution of the maps. More specifically, if the ultrasound probe is 5 millimeters in diameter and the radius of detection is 10 millimeters, then the ultrasound probe would be moved 20 millimeters to view the tissue to avoid misdetection, or the creation of a void, in the region desired.
[0040] Further, after grid points are established, scan points are determined considering the range of depth of view of the probe. This range of depth of view of the probe could be the rated range of view according to product specification, or an actual range of view according to a scan of the subject tissue. In this embodiment, scan points are separated a distance of approximately 65%> to 85%> of the rated range of depth of view of the probe, which in this embodiment is a high resolution probe, thereby creating approximately 15%> to 35%> overlap of scanning data in the "z" dimension. Scan points separated a distance of approximately 70%> to 80%) of the rated range of depth of view of the probe might be preferable, whereby approximately 20%) to 30%o overlap of scanning data in the "z" dimension is created for later integration. Without limitation, the present invention contemplates employing either a linear scanning transducer head and/or a sector scanning transducer head, the sector scanning transducer head being more compact since the transducer only has to swivel to scan a region of desired body tissue. [0041] The scanning methodology (grid and scan points) essentially provides an order and a number of ultrasound scans to perform in each of three- dimensions. Software then programs the robotic system to systematically sample the area outlined in accordance with the scanning methodology generated, through use of a pre-defined algorithm. [0042] The probe is then robotically positioned at a first grid point, defined in a "x" and "y" dimension relative to the established reference point(s), or to absolute space. The probe is then positioned into acoustic contact with the body tissue, through advancement in the "z" dimension. An orientation and location of the probe in each of three-dimensions is recorded, and an ultrasound scan is performed. [0043] The probe is then advanced a pre-determined distance in the "z" dimension, in accordance with the scanning methodology determined. The orientation and location of the probe in each of three-dimensions is again recorded, and another ultrasound scan performed.
[0044] Advancement in the "z" dimension, and subsequent ultrasound scanning, is repeated until a desired depth into the body tissue is reached, or until a pre-selected resistance to probe motion in the "z" dimension is detected, through use of a strain gauge in communication with the probe, upon which probe advancement ceases and a final ultrasound scan is performed at this "x" and "y" dimension (i.e., at the first grid point).
[0045] The probe is then retracted a distance in the "z" dimension indicative of pre-established criteria, and translated to a second grid point (a new desired location in the "x" and "y" dimension), in accordance with the scanning methodology. In this embodiment, the pre-established criteria is minimal acoustic contact between the probe and the body tissue. The strain gauge, continuously monitoring tissue resistance thereupon, monitors probe retraction in the "z" dimension until a preselected force is recognized, the force being indicative of minimal acoustic contact. The probe is then translated to the second grid point, or new location in the "x" and "y" dimension, while ensuring that the pre-selected force is maintained through adjustment of the probe position in the "z" dimension during "x" and "y" dimensional translation.
[0046] Upon probe translation to the second grid point, and assurance of acoustic contact with the body tissue, the orientation and location of the probe is recorded in three-dimensions and an ultrasound scan is performed. The above methodology (scan, advance probe, scan, advance probe, etc.) is repeated at this grid point until the desired depth is reached, or the pre-selected resistance is detected, A final ultrasound scan is performed at this "x" and "y" dimension, the probe is retracted, and then translated to the next grid point, in accordance with the scanning methodology determined. [0047] Upon completion of the above methodology for all grid points included in the scanning methodology for the body tissue under examination, construction of the three-dimensional image can be completed. Data from the ultrasound scans is integrated, overlapping topographies are matched, and a three- dimensional image is generated that identifies one or more pre-selected characteristics of the body tissue. In this embodiment, the integration of scanning data matches overlapping topographies of two or more scans in each of three-dimensions, to identify the pre-selected characteristics of body tissue. The image could identify the pre-selected characteristics of body tissue at a depth exceeding the depth of view capability of the high resolution probe. In this embodiment, the pre-selected characteristic of body tissue is density and color is used to represent regions of changing density.
[0048] An apparatus for this robotic embodiment of the present invention includes an ultrasound system having at least one probe to scan a desired region of body tissue at a plurality of locations and depths, and a position tracking system
having one or more sensors located on one or more of a patient backdrop, table, or positioning device, or on pre-selected locations of body tissue of a patient under examination, to establish one or more reference points, the position tracking system also having at least one sensor in communication with the ultrasound probe to track a location and orientation of the ultrasound probe relative to one or more of the reference points and/or absolute space. The apparatus further includes a computer- readable medium that configures a computer system to generate characteristic data for the desired region of body tissue outlined, and to generate and maintain scanning methodology based upon the characteristic data for the desired region of body tissue outlined, the operating specification data of the ultrasound probe, and other data obtained during scanning, such as a resistance to probe motion during probe positioning and advancement. Also included is a robotic positioning device that positions a probe into acoustic contact with the body tissue at desired locations (grid points) in a "x" and "y" dimension, the desired locations determined relative to the established reference points and/or absolute space, and for advancing and retracting the probe in a "z" dimension, generally representing a depth into or out of the body tissue. A memory device is included to record the generated data, the scanning data, and an orientation and location of the probe in three-dimensions during probe positioning and advancement, as well as a strain gauge located in communication with the at least one probe to monitor the resistance to probe motion. Lastly, a computer- readable medium is included to integrate data from the ultrasound scans, to match overlapping topographies, and to generate an image identifying one or more preselected characteristics of body tissue.
A second exemplary embodiment of the present invention [0049] By way of example, an operator controlled, hand-held ultrasound scanning system according to the present invention operates as follows: first, one or more reference points are established on a patient backdrop, table, or patient positioning device, or on pre-selected locations of body tissue under examination.
The reference points are established by placing one or more sensors of a position tracking system in one or more of the above-referenced locations. Another sensor of the position tracking system is placed in communication with the ultrasound probe on the hand-held device.
[0050] The operator, using the hand-held device, outlines a region of the desired body tissue, and characteristic data for the region of the body tissue outlined is
generated and stored. Software then generates a scanning methodology, in three- dimensions, based upon the characteristic data, and based upon the operational specifications of the probe. A projection of the region to be scanned is displayed on a monitor, guiding the operator to systematically move the probe in three-dimensions around the region to be imaged, until the volume is filled. The projection can be made three-dimensional through use of color, thereby showing the operator whether the full-depth region has been adequately scanned.
[0051] While viewing the monitor display, the operator accordingly moves the probe about the region of interest. The software program, having recorded the scanning methodology (i.e., grid and scan points), transmits a signal governing the taking of each ultrasound scan. In this embodiment, the taking of each ultrasound scan is directed electronically, based upon the scanning methodology determined, and the tracked orientation and location of the probe during translation by the operator. Triggering each scan electronically better ensures the generation of a static image, by removing the operator sampling bias that occurs when relying on the operator to choose scan location.
[0052] hi this embodiment, a strain gauge is positioned in communication with the probe, on the hand-held device, to monitor resistance to probe movement during operator manipulation of the probe. While the operator is capable of recognizing a force upon which continued advancement of the probe in a particular direction could be problematic, the monitoring and recording of the resistive force provides the computer software with information directed to whether every programmed grid and/or scan point can be accessed for an ultrasound scan. For instance, if the operator is manipulating the probe at a particular grid point (at a particular "x" and "y" dimension), and is advancing the probe in the "z" dimension to access, say, five scan points, and the pre-selected resistance to probe motion is reached at, say, the third scan point, the software acknowledges that the fourth and fifth scan points will not be accessed, and accordingly removes these scan points from the scanning methodology. A "calling" for these scan points, by the scanning methodology, will be removed from the monitor display, so that the operator will, at all times, have an accurate indication on the monitor display of those grid and/or scan points that must still be reached (accessed), and scanned, to complete the region of interest and acquire data adequate to generate the objective three-dimensional image desired.
[0053] Accordingly, the operator moves the hand-held device about the region of interest, with guidance from the monitor display, until all grid and scan points are accessed, as indicated by the display. Data from the ultrasound scans is then integrated, with overlapping topographies matched, to generate the three- dimensional image identifying the one or more pre-selected characteristics of body tissue.
[0054] An apparatus for this operator controlled embodiment of the present invention includes an ultrasound probe to scan a desired region of body tissue, a position tracking system to outline the desired region of body tissue, a computer- readable medium that configures a computer system to generate characteristic data for the desired region of body tissue outlined, and to generate and maintain scanning methodology based upon the characteristic data for the desired region of body tissue outlined, the operating specification data of the ultrasound probe, and other data obtained during scanning, such as a resistance to probe motion during probe positioning and advancing. The apparatus further includes a hand-held device for positioning the ultrasound probe about the desired region of body tissue in accordance with the scanning methodology generated, a strain gauge located in communication with the hand-held device to monitor the resistance to hand-held device motion, a display to guide the operator during the examination, and a memory device to record the generated data, the scanning data, and an orientation and location of the probe in three-dimensions during probe positioning and advancement. Lastly, a computer- readable medium is included to direct the scanning in accordance with the scanning methodology generated and the resistance to motion monitored, to integrate data from the ultrasound scans, to match overlapping topographies, and to generate an image identifying one or more pre-selected characteristics of body tissue.