Abstract
A scan completeness auditing system for screening a volume of tissue comprising a manual image scanning device having an imaging probe, a position tracking system configured to track and record the position of the imaging probe during use, and a controller in communication with the recording system and the manual image scanning device, the controller configured to electronically receive and record the scanned images from the manual image scanning device, and to measure an image-to-image spacing and a scan-to-scan spacing between the scanned images within scan sequence and between scan sequences respectively. The scan completeness auditing system is further adapted to provide an alert to the operator if the image-to-image or scan-to-scan spacing exceeds an acceptable value.
Claims
1. (canceled)
2. A scan completeness auditing system for use with an ultrasound imaging console in screening a volume of tissue comprising: a position tracking system configured to track and record the position of a manual ultrasonic imaging probe, the position tracking system comprising a plurality of position sensors adapted to couple to a manual ultrasonic imaging probe, the position sensors configured to provide position data for the manual ultrasonic imaging probe; and a receiver comprising a controller configured to electronically receive position data for the manual ultrasonic imaging probe from the position tracking system, electronically receive and record a first scan sequence comprising a first set of scanned images representing cross-sections of the tissue from the manual imaging probe, assign a replay dwell time to each image in the first scan sequence, the dwell time for each image being based on a relative spacing for that image in the first scan sequence computed from the position data, compute image-to-image spacing between successive images within the first scan sequence, and provide an alert when the computed spacing exceeds a maximum limit.
3. The system of claim 2, wherein the controller applies an image position tracking algorithm to determine a relative resolution between the scanned images within the scan sequence.
4. The system of claim 2, wherein the controller is configured to measure a scan-to-scan spacing between the first scan sequence and a second scan sequence, the second scan sequence comprising a second set of scanned images representing cross-sections of the tissue.
5. The system of claim 4, wherein the controller is configured to measure a scan-to-scan spacing between the first and second scan sequence by calculating the distance between a first boundary of the first scan sequence and a second boundary of the second scan sequence.
6. The system of claim 4, wherein the controller is configured to measure a scan-to-scan spacing between the first and second scan sequences by computing a pixel density for a unit volume within the screened volume of tissue and comparing the computed pixel density to a minimum pixel density value, the controller configured to provide an alert to rescan the tissue if the computer pixel density is less than the minimum pixel density value.
7. The system of claim 4, wherein the controller is configured to modify the first or second scan sequences for display by removing redundancy from at least one of the scan sequences.
8. The system of claim 2, wherein the controller is configured to compute the image-to-image spacing between scanned images within a scan sequence by measuring a distance between a first pixel in a first scanned image and a second pixel in a second scanned image, wherein the first and second scanned images are sequential images.
9. The system of claim 8, wherein the controller is configured to determine whether the measured distance between the first and second pixels exceeds a maximum distance.
10. The system of claim 2, wherein the controller is configured to compute the image-to-image spacing within the first scan sequence by measuring a maximum chord distance between a plurality of successive planar images in the first scan sequence.
11. The system of claim 2, wherein the controller is configured to compute the image-to-image spacing within the first scan sequence by calculating a pixel density for a unit volume within the screened volume of tissue, and the controller adapted to compare the calculated pixel density with a minimum pixel density value.
12. The system of claim 11, wherein the minimum pixel density value is between 9,000 pixels/cm.sup.3 to 180,000,000 pixels/cm.sup.3.
13. The system of claim 2, wherein the controller is configured to only display images of a recorded scan sequence that satisfy a predetermined imaging spacing interval.
14. The system of claim 2, wherein the controller is configured to change an image display rate of a recorded scan sequence to provide a substantially uniform spatial-temporal display of the recorded scan sequence.
15. The apparatus of claim 2, wherein the receiver includes a cable configured to engage with a video output of the ultrasound imaging console.
16. The system of claim 2 wherein the controller is further configured to derive orientation data for the manual ultrasonic imaging probe from the position data.
17. A method for screening tissue, comprising: scanning the tissue with a manual ultrasonic imaging probe of an ultrasound imaging console along a first scanning path on the tissue; generating a first scan sequence comprising a first set of discrete digital images representing cross-sections of the scanned tissue along the first scanning path; electronically transmitting the first scan sequence to a controller; electronically communicating position data for the manual ultrasonic imaging probe to the controller, wherein the position data is collected from a plurality of position sensors; assigning a display dwell time to each image based on a relative spacing for that image in the first scan sequence computed from the position data; computing image-to-image spacing between successive images within the first scan sequence, and generating an alert when the computed spacing exceeds a maximum limit.
18. The method of claim 17 further comprising: computing an image-to-image spacing between successive images in the first scan sequence based on the position data communicated to the controller; determining whether the image-to-image spacing exceeds a maximum limit; and generating an alert when the spacing exceeds a maximum limit.
19. The method of claim 18, further comprising: generating a second scan sequence, the second scan sequence comprising a second set of discrete digital images along a second scanning path on the tissue; computing a scan-to-scan spacing between the first and second scan sequences; determining whether the computed scan-to-scan spacing exceeds a scan-to-scan spacing limit; and generating an alert when the scan-to-scan spacing exceeds the scan-to-scan spacing limit.
20. The method of claim 19, wherein the image-to-image spacing and the scan-to-scan spacing are calculated based on the position data communicated to the controller and orientation data derived from the communicated position data.
21. The method of claim 19, wherein each of the images in the first and second sets of discrete digital images comprises a matrix of pixels, each matrix having the same fixed number of rows and columns and each pixel in each matrix having a row and column location designed by r.sub.x, c.sub.x, x being the same or different for r and c, wherein computing the scan-to-scan spacing between the first and second scan sequences comprises calculating a plurality of pixel-to-pixel distances between a first pixel P(r.sub.x, c.sub.x) in a first image of the first scan sequence and a plurality of pixels in the second scan sequence, wherein the plurality of pixels in the second scan sequence have the same row location r.sub.x as the first pixel P.
22. The method claim 19 further comprising removing a redundant image from the first scan sequence or the second scan sequence.
23. The method of claim 18, wherein the computing an image-to-image spacing step comprises calculating a pixel density for a unit volume of the screened tissue; and the determining step comprises comparing the calculated pixel density to a minimum pixel density value.
24. The method of claim 18, wherein computing the image-to-image spacing step comprises calculating a maximum chord distance between images in the first scan sequence.
25. The method of claim 18, wherein computing the image-to-image spacing within the first scan sequence comprises: calculating a maximum pixel distance between a first image and a second image of the first scan sequence, the first image having a first pixel matrix and the second image having a second pixel matrix, wherein the first and second pixel matrices each have the same number of rows and columns; and determining the maximum pixel distance by measuring a pixel-to-pixel distance between at least two corresponding pixels, wherein one of the at least two corresponding pixels is in the first pixel matrix and the other of the at least two corresponding pixels is in the second pixel matrix, the corresponding pixels having the same row and column locations in respective matrices.
26. The method of claim 25, wherein determining the maximum pixel distance comprises computing the pixel-to-pixel distance between a corner pixel on the first pixel matrix and a corresponding corner pixel on the second pixel matrix.
27. The method of claim 17 further comprising deriving orientation data for the manual ultrasonic imaging probe based on the position data communicated to the controller.
28. The method of claim 17, further comprising prior to scanning, attaching the plurality of position sensors to the manual ultrasonic probe.
29. The method of claim 17, wherein the first scan sequence is transmitted from a video output of an ultrasound imaging console in communication with the ultrasonic imaging probe to the controller.
30. The method of claim 29, further comprising prior to scanning, attaching a cable to the video output of the ultrasound imaging console to the controller, wherein the first scan sequence is electronically transmitted by the cable.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0102] The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
[0103] FIG. 1 is a schematic view of the disclosed system including its various subsystem components.
[0104] FIG. 2 illustrates the hand-held ultrasound probe assembly including the affixed position sensors.
[0105] FIG. 3 illustrates an exploded view of the hand-held ultrasound probe assembly revealing the first and second support members, which encase the hand held ultrasound probe and incorporate the position sensors.
[0106] FIG. 4 illustrates a side view of the first support member shown in FIG. 3;
[0107] FIG. 5 illustrates a first transverse sectional view of the first support member shown in FIG. 3 revealing the conduits for incorporation of the position sensors and leads;
[0108] FIG. 6 illustrates a second transverse sectional view of the first support member shown in FIG. 3 revealing the conduits for incorporation of the position sensors and leads.
[0109] FIG. 7 illustrates a first cross-sectional view of the human breast including the hand-held ultrasound probe assembly shown at various positions during the course of a scan sequence.
[0110] FIG. 8A illustrates discrete images in a scan sequence.
[0111] FIG. 8B illustrates a second cross-sectional view of the human breast including the hand-held ultrasound probe assembly shown at various positions during the course of a scan sequence;
[0112] FIG. 9 illustrates a perspective view of the human breast and a ultrasound scan sequence including the hand-held ultrasound probe assembly shown at one position during the course of a scan sequence.
[0113] FIG. 10A illustrates a first top view of the human breast illustrating the locations of 14 scan sequences.
[0114] FIG. 10B illustrates a second top view of the human breast illustrating the locations of 13 scan sequences;
[0115] FIG. 10C illustrates a perspective view of the human breast illustrating the locations of 2 scan sequences and volume of tissue included within 2 scan sequences.
[0116] FIG. 10D illustrates a third top view of the human breast with a plurality of scan sequences.
[0117] FIG. 10E illustrates a fourth top view of the human breast with a plurality of scan sequences.
[0118] FIG. 10F illustrates two radial scan sequences.
[0119] FIGS. 10G-10L illustrate discrete images in two scan sequences.
[0120] FIG. 10M illustrates two radial scan sequences.
[0121] FIG. 11A-11F combine as labeled thereon to show a flow chart of the procedure associated with a described embodiment.
[0122] FIG. 12A illustrates the superposition of a single component volume unit on two sequential two-dimensional ultrasound scan images;
[0123] FIG. 12B illustrates the superposition of four component volume units at each of the corners of both planes of two sequential two-dimensional ultrasound scan images.
[0124] FIG. 13 is a schematic view of the disclosed system based on optical-based position sensing including its various subsystem components.
[0125] FIGS. 14A-14C illustrate a hand-held ultrasound probe assembly including affixed optically unique position sensors.
[0126] FIG. 15 illustrates an exploded view of a hand-held ultrasound probe assembly revealing the first and second support members, which encase the hand held ultrasound probe and incorporate the optically unique position sensors.
[0127] FIGS. 16A-16B illustrate the spacing between adjacent ultrasound scan images as a function of the depth of the ultrasound image within the tissue.
[0128] FIGS. 17A-17B illustrate a top view of a plurality of scan sequences with overlap.
DETAILED DESCRIPTION
[0129] As described briefly above, embodiments contemplated provide for methods, devices, systems that can be used with manual imaging techniques to ensure satisfactory quality and adequate completeness of a scanning procedure for a patient's target region. Some embodiments employ rapid-response position sensors or rapidly imaged optical registers affixed to an existing hand-held imaging system, for example, a diagnostic ultrasound system, and associated hand-held imaging probes. By way of example, one type of ultrasound system that can be used with some embodiments described is the Phillips iU22 xMatrix Ultrasound System with hand-held L12-50 mm Broadband Linear Array Transducer (Andover, Mass.). Also, a commercially available system which provides accurate x, y, z position coordinates for multiple sensors as a function of time, providing said position information at a rapid tracking rate, is, by way of example, the Ascension Technology 3D Guidance trakSTAR (Burlington, Vt.).
[0130] Referring to FIG. 1, two principal subsystems are illustrated. A first subsystem is the hand-held imaging system 12, which includes hand-held imaging monitor console 18, display 17, hand-held imaging probe 14 and connecting cable 16. A second system (referred to hereinafter as the Scan Completeness Auditing System), according to the invention, is represented in general at 10. The Scan Completeness Auditing System 10 comprises a data acquisition and display module/controller 40 including microcomputer/storage/DVD ROM recording unit 41, display 3 and footpedal or other control 11. Foot pedal 11 is connected to microcomputer/storage/DVD ROM recording unit 41 via cable 15 and removably attachable connector 13. The Scan Completeness Auditing System 10 also comprises position-tracking system 20, which includes, by way of example, position tracking module 22 and position sensor locator, such as a magnetic field transmitter 24. In addition, the Scan Completeness Auditing System 10 also comprises a plurality of position sensors 32a, 32b and 32c affixed to the hand-held imaging probe 14. Although the hand-held imaging system 12 is shown as a subsystem separate from the scanning completeness auditing system 10, in some embodiments, the two systems are part of the same overall system. In some cases, the imaging device may be part of the scanning completeness auditing system.
[0131] Still referring to FIG. 1, hand-held imaging system 12 is connected to data acquisition and display module/controller 40 via data transmission cable 46 to enable each frame of imaging data (typically containing about 10 million pixels per frame) to be received by the microcomputer/storage/DVD ROM recording unit 41 the frequency of which is a function of the recording capabilities of the microcomputer/storage/DVD ROM recording unit 41 and the image data transmission capabilities, whether it is raw image data or video output of the processed image data, of the hand-held imaging system 12. Position information from the plurality of position sensors 32a, 32b, and 32c, is transmitted to the data acquisition and display module/controller 40 via the transmission cable 48. Cable 46 is removably attached to microcomputer/storage/DVD ROM recording unit 41 of data acquisition and display module/controller 40 with removably attachable connector 43 and is removably connected to diagnostic ultrasound system 12 with connector 47. The successive scans associated with the hand-held imaging procedure are stored and subjected to computational algorithms to assess completeness of the diagnostic ultrasound scanning procedure as described in greater detail in the specifications which follow.
[0132] Still referring to FIG. 1, position tracking module 22 is connected to data acquisition and display module/controller 40 via data transmission cable 48 wherein cable 48 is removably attached to microcomputer/storage/DVD ROM recording unit 41 of data acquisition and display module/control 40 with connector 45 and is removably connected to position tracking module with connector 49. Position sensor locator, such as a magnetic field transmitter 24 is connected to position tracking module 22 via cable 26 with removably attachable connector 25. Hand-held imaging probe assembly 30 seen in FIG. 1 includes, by way of example, position sensors 32a-32c, which are affixed to hand-held imaging probe 14 and communicate position data to position tracking module 22 via leads 34a-34c, respectively, and removably attachable connectors 36a-36c, respectively. Position sensor cables 34a-34c may be removably attached to ultrasound system cable 16 using cable support clamps 5a-5f at multiple locations as seen in FIG. 1
[0133] Referring now to FIG. 2, the position-sensor instrumented hand-held imaging probe is described in greater detail. In one embodiment, the hand-held probe assembly 30, a hand-held imaging probe 14 is enclosed within first and second clamshell type support members 42 and 44, respectively. First support member 42 incorporates three raised ridges 35a-35c, which provide three conduits (not shown) for position sensors 32a-32c, respectively, and position sensor cables 34a-34c, respectively.
[0134] Another embodiment is further illustrated in an exploded view of the hand-held probe assembly 30 as seen in FIG. 3. Said first support member 42 includes the aforementioned raised ridges 35a-35c and associated conduits 33a-33c, respectively, which accommodate position sensors 32a-32c and their corresponding cables 34a-34c, respectively. First support member 42 also incorporates extension ears 36a and 36b, each with a drilled hole to enable secure mechanical attachment to second support member 44. Said second support member 44 likewise incorporates extension ears 38a and 38b, each with a drilled hole which matches drilled holes in first support member to enable secure mechanical attachment to second support member 42 using screws 39a and 39b, respectively. First and second support members may be manufactured using a non-ferromagnetic metal or alloy or, preferably, an injection molded plastic. The interior contours and dimensions of the first and second support members 42 and 44 are designed to match the particular contour and dimensions of the off-the-shelf hand-held ultrasound probe being instrumented with the position sensors 32a-32c. Accordingly, the contours and dimensions of the first and second support members 42 and 44 will vary according the hand-held ultrasound probe design. The exact location of the position sensors 32a-32c relative to the ultrasound transducer array at the end face of the hand-held imaging probe (not shown) will accordingly be known for each set of first and second support members since they are designed to attached to and operate in conjunction with a specific hand-held ultrasound probe.
[0135] Additional features of first support member 42 are revealed in FIGS. 4, 5 and 6 which illustrate an embodiment of the first support member 42 in a side view (see FIG. 4) and sectional views (see FIGS. 5 and 6) at two locations along the length of first support member 42. As seen in FIG. 4, the raised ridge 35a is seen which extends along most of the length of first support member 42. Also, extension ear 36a is seen one end of the first support member 42. Referring to FIGS. 5 and 6, which provides transverse cross-sectional views of first support member 42, conduits 33a, 33b and 33c are revealed. The dimensions of conduits 33a-33c are selected to accommodate position sensors 32a-32c and their corresponding cables 34a-34c, respectively. By way of example, position sensors are commercially available which have a diameter of nominally 2 mm or less. Accordingly, one described embodiment provides conduits 33a-33c dimensioned to accommodate a 2 mm diameter position sensor. As seen in FIGS. 2, 3, 5 and 6, position sensors 32a-32c and their respective cables 34a-34c can be affixed within conduits 33a-33c using an adhesive (e.g., epoxy or cyanoacrylate).
[0136] Returning to FIG. 2, by way of example, the typical dimensions of a hand-held ultrasound probe 14 are provided below: [0137] W1=1.5 to 2.5 inches [0138] L1=3 to 5 inches [0139] D1=0.5 to 1 inch
[0140] Accordingly, as specified in the previous paragraph, the first and second support members 42 and 44 are sized to correspond to the particular contour and dimensions of a specific hand-held ultrasonic probe design. For the case of injection-molded plastic, e.g., a biocompatible grade of polycarbonate, the inner dimensions of said first and second support members 42 and 44 are designed to closely match the outer dimensions of the hand-held ultrasound probe 14. The wall thickness, t1 (see FIG. 5) of the injection molded plastic support members 42 and 44 is preferably in the range from 0.05 to 0.10 inch.
[0141] An example of the use of described embodiments is seen in FIG. 7 for the case of the hand-held ultrasound examination of a human breast 60. In the example seen in FIG. 7, a hand-held ultrasound probe assembly 30 with affixed position sensors is illustrated at a starting position on the human breast 60 adjacent to the nipple 64 and areola 62. In an example hand-held ultrasound scanning procedure of the human breast 60, the hand-held ultrasound probe assembly 30 starts immediately over the nipple and progresses radially and follows the contour of the human breast as illustrated by translation vectors 52a-52b and 52b-52c corresponding to hand-held ultrasound probe assembly 30 successive positions 30a, 30b and 30c with the latter two positions shown in phantom format. During the scan sequence, the ultrasound transducer array 57 is maintained in direct contact with the skin, usually with an intervening layer of an ultrasound coupling gel. An ultrasound coupling gel is usually used (e.g., Aquasonics 100, Parker Laboratories, Inc., Fairfield, N.J.) to improve ultrasound interrogation by providing an improved acoustic pathway between the ultrasound transducer array and the skin.
[0142] By way of example, the hand-held ultrasound probe assembly 30 is moved by the operator using a manual technique along the pathway illustrated in FIG. 7, referred to herein as a single scan sequence, beginning at the nipple 64 and ending when the ultrasound transducer array has reached the surface of the chest 61 beyond the perimeter of the breast 60, or beginning at the chest wall and ending when the ultrasound transducer has reached the nipple. If this example scan sequence is performed within the acceptable limits of translation speed and rate of change of the orientation of the hand-held ultrasound probe assembly 30, then this scan sequence would be verified as a complete scan sequence. As seen in FIG. 7, a planar ultrasound beam 50a-50c is emitted and a corresponding ultrasound image is obtained at each momentary position 30a-30c of the hand-held ultrasound probe assembly 30. As the hand-held ultrasound probe assembly 30 is translated along the illustrated scan sequence path in FIG. 7, an ultrasound beam is emitted and an image is received, constituting a single image frame, at a rate in the range from about 10 to 40 times (or frames) per second. A typical frame may contain an array of 400600 pixels of image data or 240,000 pixels per frame. A new frame is obtained at a rate of about 10 to 40 frames per second.
[0143] An important aspect of the present invention is illustrated in FIGS. 8A, 8B, and 9 related to computing (or auditing) the completeness of each scan sequence. This described method and algorithm assures the frame-to-frame resolution of any individual scan sequence (e.g., any individual path scanned beginning at the nipple of the breast and ending at the chest surface beyond the perimeter of the breast boundary, or scan beginning at the chest surface and ending at the nipple, or any scan beginning at the clavicle and ending at the base of the rib cage, or any scan beginning at the base of the rib cage and ending at the clavicle, or any scan beginning in the crevice of the armpit and ending at the inferior lateral side of the rib cage).
[0144] In some embodiments, measuring or calculating the spacing or distance between individual images in a scan sequence may be referred to as determining the image-to-image resolution or spacing between discrete images in a scan sequence. Alternatively, frame to frame resolution may also be used to describe the spacing/distance between images in a scan sequence.
[0145] By way of example and referring first to FIG. 8.A, the hand-held ultrasound probe assembly 30 is translated across the surface of the skin by the human hand 700. That translation will follow a linear or non-linear path 704, and there are a series of corresponding ultrasound beam positions 50s-50v, each with a corresponding ultrasound image that is recorded, as depicted in FIG. 1, by the acquisition and display module/controller 40 via the data transmission cable 46, to be received by the microcomputer/storage/DVD ROM recording unit 41, the frequency of which is a function of the recording capabilities of the microcomputer/storage/DVD ROM recording unit 41 and the image data transmission capabilities. Again referring to FIG. 8A, the images are stored as a set of pixels, including pixels 94a-94l, which are displayed in a two-dimension matrix of pixels, each matrix consisting of horizontal rows 708a-708h and vertical columns 712a-712h. A single pixel 94a-94h, is displayed has a unique display address P(r.sub.x, c.sub.x), where r.sub.x is the row of pixels on the image, r.sub.1 being the row at the top, e.g. 708e, or the row representing structures closest to the probe, and r.sub.last being the row at the bottom (e.g. 708f), or the row representing structures furthest away from the probe; and where c.sub.x is the column of pixels on the image, c.sub.1 being the column on the left (as viewed by the reviewer, e.g. 712g), and c.sub.last being the column on the right (as viewed by the reviewer, e.g. 712h). A typical recorded ultrasound image will have between 300 and 600 horizontal rows 708 and between 400 and 800 vertical columns 712. Thus, a typical recorded ultrasound image shall have between 120,000 and 480,000 pixels 94.
[0146] Referring again to FIG. 8A, the recorded image for each ultrasound beam position 50s-50v will have an identical pixel format. A corresponding row is the row 708 which is displayed at the same distance, vertical from the top, in every image. The depth, as measured as distance away from probe, shall be the same for corresponding horizontal rows 708. In the way of example, the information in the 8.sup.th horizontal row 708 in one image represents structures which are the same distance, away from the probe at the time they are recorded, as the location of the information in the 8.sup.th horizontal row 708 in another image at the time that image is recorded. The same logic applies to the corresponding vertical columns 712. By way of example, the information in the 12.sup.th vertical column 712 in one image represents structures that are the same distance, horizontally, from the center of the probe at the time that image is recorded as the location of the information in the 12.sup.th vertical column 712 in another image at the time it is recorded. Thus, the information described any one pixel 94, P(r.sub.x, c.sub.x), in one image is the same distance away from the surface of the probe (depth) and from the center line of the probe as the information described at the same pixel 94 location P(r.sub.x, c.sub.x), in another image. These pixels 94 that share common locations on the image format for the discrete images in the image sets are termed corresponding pixels 94.
[0147] One embodiment for calculating the completeness of the scan sequence in terms of frame-to-frame resolution is to calculate the maximum distance between any two adjacent image frames. Since the concept of minimum acceptable resolution, by definition, requires the establishment of a maximum acceptable spacing, then that resolution requirement will be met if the largest distance 716 between any two corresponding pixels 94 in adjacent image frames is within the acceptable limit. Since the frames are planar, then the largest distance between any two frames will occur at the corresponding pixels 94 that are at one of the four corners. Thus, the maximum distance 716 between any two corresponding frames shall be (EQ. 1):
{Maximum Distance between any Two Corresponding Frames}==MAX(DISTANCE(P(FIRST-ROW, FIRST-COLUMN)P(FIRST-ROW, FIRST-COLUMN)), DISTANCE(P(FIRST-ROW, LAST-COLUMN)P(FIRST-ROW, LAST-COLUMN)), DISTANCE(P(LAST-ROW, FIRST-COLUMN)P(LAST-ROW, FIRST-COLUMN)), DISTANCE(P(LAST-ROW, LAST-COLUMN)P(LAST-ROW, LAST-COLUMN))) [0148] Where P and P are the corresponding pixels 94 in two adjacent images, MAX is the maximum function which chooses the largest of the numbers in the set (in this example 4) and DISTANCE is the absolute distance 716 between the corresponding pixels.
[0149] Exemplary distances are shown in FIG. 8A at 716a between pixel 94a and corresponding pixel 94b; 716b between pixels 94b and 94c; 716c between 94c and 94d; 716d between 94e and 94i; 716e between 94f and 94i; 716f between 94g and 94k; and 716g between 94i and 94l. This method of assuring frame-to-frame resolution may be used to assure that the resolution remains within limits regardless of the speed of longitudinal translation of the probe, speed of lateral rotation of the probe, speed of axial resolution of the probe, or speed of vertical rotation of the probe. If the distance between pixels exceeds an acceptable spacing/distance then the user may be prompted during or at the end of the process/procedure to rescan a region. In some cases, the acceptable spacing/distance is a preselected or predetermined value. In some cases, the value is a user defined limit. In other embodiments, the system may provide a range or acceptable spacing/distances for selection based on the type of exam or characteristics of the patient or target region for scanning.
[0150] FIG. 8B provides another method of assuring adequate frame-to-frame or image-to-image spacing. FIG. 8B shows the hand-held ultrasound probe assembly 30 at two adjacent positions 30d and 30i. For this example, assume that the rate of producing new ultrasound images is accomplished at a rate of 10 frames/second. As the hand-held ultrasound probe assembly 30 is translated from position 30d with corresponding ultrasound beam 50d and a corresponding ultrasound image to position 30i with corresponding ultrasound beam position 50i and a corresponding ultrasound image, there are 4 intermediate positions as seen by ultrasound beams 50e-50h. Also, assume that the rate of longitudinal rotation of the hand-held ultrasound probe assembly 30 during the translation from position 30d to 30i is not uniform and an increased rate of rotation of the hand-held ultrasound probe assembly 30 inadvertently occurs between ultrasound beam 50g and 50h. For the case of the example illustrated in FIG. 8B, the time step, t is 0.10 second based on an ultrasound scan rate of 10 frames per second. As a result of a faster than allowed rate of rotation between beam position 50g and 50h and corresponding ultrasound images, a set of omitted zones 70a-70e within the targeted tissue (i.e., the human breast 60 in this example) are not included in the ultrasound scan sequence. As a consequence, if a suspicious lesion 73 were within omitted zone 70d, it would not be detected or recorded in the diagnostic ultrasound procedure. Unavoidably, it would be impossible for the expert (e.g., radiologist) who analyzes the ultrasound images following the ultrasound procedure to detect the presence of what could become a life-threatening malignant lesion. It is not mathematically possible to eliminate these omitted zones 70a-70e without an infinite number of ultrasound beams 50d-50i and corresponding ultrasound images, but the user can determine a level of resolution, that is the maximum acceptable size, of the zones 70a-70e and notify the user if any one of those zones exceeds that acceptable limit.
[0151] Still referring to FIG. 8B, a preferred algorithm for computing spacing between images in a scan (e.g. image-to-image spacing) is to compute the maximum chord or distance, x between successive planar ultrasound scan frames at the maximum intended depth of ultrasound interrogation (i.e., maximum depth of the breast tissue in the present example). This maximum distance, x can be computed between the distal boundaries of each successive ultrasound scan frame (e.g., between ultrasound beam 50g and 50h, and corresponding images, since the position of the ultrasound transducer array 57 and the orientation of the hand-held ultrasound probe assembly 30 is precisely known at all time points when ultrasound scan frames are generated and recorded. For the case of one embodiment of the present invention involving the use of the Ascension Technologies position sensor product, the position of each sensor is determined (in one example version of a product sold by Ascension Technologies but not intended as a limitation as the data update rate may be higher or lower) at a rate of 120 times per second which is an order of magnitude more frequently than the repetition rate for ultrasound scan frames. As a consequence, the precise location of the ultrasound scan frame and, thereby, the precise location of the 240,000 pixels within each ultrasound scan frame, will be known in three-dimensional space as each ultrasound scan frame is generated by the ultrasound system 12 and recorded by the data acquisition and display module/controller 40. According, knowing the position of all pixels within each successive frame will enable the maximum distances between corresponding pixels in successive frames to be computed, focusing on those portions of successive ultrasound beams 50d-50h, and corresponding ultrasound images, that are known to be furthest apart, i.e., at locations within the recorded scan frame most distant from the ultrasound transducer array 57.
[0152] Referring now to FIG. 9, another algorithm for computing the acceptability of the speed of translation and/or the rate of change of the orientation of the hand-held ultrasound probe assembly 30 is illustrated. This alternative method and algorithm for assuring the completeness of any individual scan sequence (e.g., any individual path scanned beginning a the nipple of the breast and ending at the chest surface beyond the perimeter of the breast boundary) involves computation of the pixel density in each unit volume 96 within the swept volume 90 of the scan sequence, i containing N ultrasound beams 50[i,j(i)] and associated recorded frames where i equals the number of scan sequences and j(i) equals the number of emitted beams 50 and associated recorded frames for each scan sequence, i. By way of example and still referring to FIG. 9, assume that the rate of translation of the hand-held ultrasound probe assembly 30 along scan sequence, i, having path length, L2, is 1.0 cm/second, length L2 equals 15 cm and the ultrasound system 12 scanning rate is 10 frames/second and the resultant images are recorded by the data acquisition and display module/controller 40 at 10 frames/second. Based on these example parameters, the total time to complete the scan is 15 seconds and the total number of ultrasound scan frames recorded is 150. In this example, j(i) equals 150. If each frame contains, for example, 240,000 pixels, then the total volume will include 150 frames240,000 pixels/frame which equals a total of 36 million pixels in the swept volume 90 of an individual scan sequence, i. Since the precise position and computed orientation of the hand-held ultrasound probe assembly 30, its ultrasound beam 50[i,j(i)] and its associated frame of pixels are known at the moment of each recorded frame, then the precise location of the plane in which each pixel 94 resides within the swept volume 90 can be computed.
[0153] Still referring to FIG. 9, according to the teachings of this invention, the swept volume 90 of the scan sequence would be the volume defined by (a) the width, W2 of the ultrasound beam, which is defined by the length of the ultrasound transducer array (e.g., 5 cm), (b) the depth, D2 of the recorded penetration of the ultrasound beam into the targeted living tissue (e.g., 5 cm) and (c) the total length, L2 traversed in an individual scan sequence (e.g., 15 cm). This total volume (375 cubic cm in the present example) is then subdivided into unit volumes exemplified by unit volume 96 (e.g., cubical volume of dimensions 1.0 cm1.0 cm1.0 cm). For this example, the swept volume 90 would be subdivided in to 375 unit volumes 96. The number of ultrasound scan pixels 94 contained in each unit volume 96 is computed and this number is compared to a predetermined Minimum Pixel Density number. By way of example, but not limiting the invention, the number of ultrasound scan pixels 94 within a unit volume 96 may be computed by comparing the x-y-z coordinates of each of the ultrasound scan pixels 94 in the 150 frames which comprise the swept volume 90, with the x-y-z coordinates of the boundaries of the perimeter of the unit volume 96. If the x-y-z coordinates of the ultrasound scan pixel 94 is within the boundaries of the perimeter of the unit volume 96, it is counted. If the x-y-z coordinates of the ultrasound scan pixel 94 is outside of the boundaries of the perimeter of the unit volume, it is not counted. If the computed pixel density within any unit volume 96 (i.e., any of the 375 unit volumes in this example) within the swept volume 90 is less than the Minimum Pixel Density, then the operator is alerted at the end of the scan sequence that scan sequence just completed is incomplete and that all or part of it must be repeated, or that the operator must accept that the scan sequence is incomplete. Said alert includes a display of the scan path just completed as well as instructions to the operator to improve scanning method to achieve a complete scan. For example, these instructions include reducing the scanning speed and/or the rate of change of orientation of hand-held ultrasound probe during the repeated scan sequence.
[0154] In some embodiments, the range of the image-to-image resolution (spacing) within each scan sequence is a pixel density between 9,000 and 180,000,000 pixels/cm.sup.3. In other embodiments, the pixel density is between 22,500 and 18,000,000 pixels/cm.sup.3. In further embodiments, the pixel density is between 45,000 and 3,550,000 pixels/cm.sup.3.
[0155] An equally important aspect of the present invention is illustrated in FIGS. 10A and 10B related to computing (or auditing) the tissue coverage by comparing the scan sequence just completed based on its relative distance from the previously completed scan sequence. According to the teachings of this invention and referring to FIG. 10A, the accurate and dynamic computation of the position of the hand-held ultrasound probe's transducer array enables the computation of the actual spatial position and computed orientation of sequential and manually scanned pathways completed along the tissue surface. By way of example, relatively uniformly and closely spaced radial scan sequences 80a-80l are superimposed on a top view of the human breast 60 as seen in FIG. 10A with scan sequences 80 spanning the distance between the nipple 64 and some distance radially outward from the nipple, for example, the chest surface 61. Each scan sequence 80 has a length L and a width W. The computed position and computed orientation of each sequential and manually derived scan sequence 80a-80l scanned along the tissue surface enables the further computation of the physical spacing between the boundaries of each adjacent and successive scan sequence 80. This computation can be rapidly completed during the course of the manual scanning process and a visual and audible cue as well as an image is provided showing the paths of completed scan sequences to identify where re-scanning is required. This intra-procedure computation of the distances between adjacent scan sequences, 80a-80l assures that complete coverage of the ultrasound scan of the targeted tissue region is achieved by identifying any completed scan sequences that are separated by an unacceptably large distance.
[0156] Referring now to FIG. 10B, radial scan sequences 80a-80l are superimposed on a top view of the human breast 60 with scan sequences 80 spanning the distance between the nipple 64 and the chest surface 61. In contrast to the example seen in FIG. 10A, this example illustrates an abnormally large spacing between scan sequence 80d and 80e. As a consequence of an inadvertently large spacing between scan sequences 80d and 80e, a zone 72 (as revealed by shaded region in FIG. 10B) by of tissue within the breast 60 is not included in the diagnostic ultrasound procedure. The distance between successive scan sequences can be computed since the precise location and computed orientation of the hand-held ultrasound probe assembly 30 is known for each scan sequence 80. If the spacing between scan sequences exceeds a predetermined maximum distance between successive scans, then a visual and audible cue is issued as well as an image is displayed showing the paths of completed scan sequences to identify where re-scanning is required. This intra-procedure computation of the distances between adjacent scan sequences assures that a complete diagnostic ultrasound scan of the targeted tissue region is achieved by identifying any completed scan sequences that are separated by an unacceptably large distance.
[0157] Still referring to FIG. 10B, the result of a computed physical spacing between successive scan sequences 80d and 80e being greater than a predetermined maximum spacing value is an un-scanned or omitted zone 72 within the targeted tissue (i.e., the human breast 60 in this example). As a consequence, if a suspicious lesion 73 were within omitted zone 72, it would not be detected or recorded in the diagnostic ultrasound procedure. Unavoidably, it would be impossible for the expert (e.g., radiologist) who subsequently analyzes the recorded ultrasound images following the diagnostic ultrasound procedure to detect the presence of what could become a life-threatening malignant lesion.
[0158] Similarly, FIGS. 10D and 10E show scan-to-scan spacing between relatively linear scan sequences. FIG. 10D shows scan sequences 80m-80q following a substantially linear pathway across the breast 60. The sequences show overlapping imaging at 3999, 4001, 4003, and 4005. FIG. 10E, on the other hand, illustrates a gap of unscanned tissue between scan sequence 1500 and scan sequence 1502. In such circumstances, embodiments described would be used to calculate, measure, or determine the size of the unscanned region 63. If the distance is greater than an acceptable spacing for scan-to-scan spacing, then the operator would be alerted during the procedure to scan the region 63.
[0159] FIGS. 10F and 10M show scan-to-scan spacing between relatively radial scan sequences. Two scan sequences 1500 and 1502 show unscanned regions 1504a and 1504b. In such cases, embodiments described would be used to calculate, measure, or determine the size of the unscanned region. If the distance is greater than an acceptable spacing for scan-to-scan spacing, then the operator would be alerted during the procedure to scan the region.
[0160] In some embodiments, measuring or calculating the spacing or distance between scan sequences may be referred to as determining the scan-to-scan spacing between scan sequences. Scan-to-scan spacing is a method of measuring, calculating, or otherwise determining coverage. If the images in the scan sequences overlap, there is coverage. If there is a gap between the two scan sequences, there is incomplete coverage.
[0161] Referring to FIG. 10G, two adjacent scan sequences 2900a-2900d and 2904a-2904d are depicted. One means of measuring whether there is overlap or gap spacing is to measure the distances 2908a-2908d from one of the corner pixels of one image, for example P(FIRST-ROW, LAST-COLUMN) 2916 and each of the pixels in the same row, but opposite side of the image in all of the images in the adjacent row, for example P(FIRST-ROW, FIRST-COLUMN) 2920a-2920d. The shortest of those distances represents the spacing between adjacent images in adjacent rows. In the example of FIG. 10G, that would be distance 2908b. If the vector of that distance, that is the vector from 2916 to 2920b, shown at 2913, is in the same general direction as the vector which emanates from that corner pixel and the pixel on the same row, but opposite side of the image 2912, as is the case of the vector between 2916 and 2920b (2913) and the vector 2912, then the distance between the corner pixels of the two adjacent images represents an overlap. In other words, if the angle 2915 between the two vectors 2912 and 2913 is less than 180 degrees, then the two pixels overlap. Referring now to FIG. 10H, and measuring the distance between pixel 2948 and the corner pixels of the other images 2920a-2920d, the shortest distance is between pixel 2948 and 2920d. The vector of that distance 2945 is in the opposite general direction as the vector 2944 along the top row of image 2944, so the distance represents a gap. In other words, if the angle 2949 between the two vectors 2944 and 2945 is greater than 180 degrees then the two pixels represent a gap.
[0162] Referring to FIGS. 10I and 10K, two adjacent scan sequences 2900a-2900d and 2904a-2904d are depicted. One means of measuring whether there is overlap or gap spacing is to measure the distances 2908a-2908d from one of the corner pixels of one image, for example P(FIRST-ROW, LAST-COLUMN) 2916 and each of the pixels in the same row, but opposite side of the image in all of the images in the adjacent row, for example P(FIRST-ROW, FIRST-COLUMN) 2920a-2920d. The shortest of those distances represents the spacing between adjacent images in adjacent rows. In the example of FIGS. 10I and 10K, that would be distance 2908b. The border pixel 2916 is considered to overlap with the adjacent scan sequence of images 2900a-2900b if the pixel is within the borders of the area 2953 described, in part, by the row of the closest image 2900b and the adjacent image 2900a. Referring now to FIGS. 10J and 10L, and measuring the distance between pixel 2948 and the corner pixels of the other images 2920a-2920d, the shortest distance is between pixel 2948 and 2920d. The border pixel 2948 is considered to have a gap with the adjacent scan sequence of images 2900a-2900b if the pixel is outside of the borders of the area 2955 described, in part, by the row of the closest image 2900d and the adjacent image 2900c.
[0163] Referring now to FIG. 10B and 10C, an alternative algorithm is employed wherein the volume subjected to successive scan sequences 80a-80m is transformed into the computed distribution of ultrasound scan image pixels based on the known position and computed orientation of the hand-held ultrasound probe assembly 30 for each scan sequence as described above in connection with FIG. 9. Using this alternative algorithm, the pixel density per unit volume (e.g., pixel density per cubical 1.0 cubic centimeter or pixel density per cubical 0.5 cubic centimeter unit volumes) can be computed for the included volume bounded by all successive scan sequences. By way of example and still referring to FIGS. 10B and 10C, the included volume 75 bounded by successive scan sequences 80d and 80e, would be subdivided into smaller unit volumes 79. The computed position of all pixels within the included volume 75 between scan sequences 80d and 80e would then be computed, based on the known position and computed orientation of the hand-held ultrasound probe assembly 30 during periods within each scan sequence, thereby allowing the computation of pixel density within each unit volume 79. The number of ultrasound scan pixels (as described above in connection with FIG. 9) contained in each unit volume 79 is computed and this number is compared to a predetermined Minimum Pixel Density number. If the computed pixel density within any unit volume 79 within the included volume 75 is less than the Minimum Pixel Density, then the operator is alerted at the end of the scan sequence that scan sequence just completed is incomplete and that it must be repeated including a display of instructions to improve the scanning method (e.g., reduce the spacing between the previous scan sequences and the present scan sequence to be repeated).
[0164] Turning now to FIGS. 11A through 11E, a flow chart describes one embodiment of the method and system of the present invention. Beginning as represented by symbol 3100 and continuing as represented by arrow 3102 to block 3104, connectivity of the components of the system is verified. The user must verify that the hand-held ultrasound imaging probe is connected to the ultrasound system, that the position sensors are attached to the hand-held ultrasound probe, that the position sensors are connected to the position tracking module, that the magnetic field transmitter (MFT) component of the position tracking module is within 24 inches of the targeted patient volume (e.g. the patient's breast), that there are no electromagnetic materials within 36 inches of the MFT (i.e., a requirement specifically related to the use of the Ascension Technology position detection product), that there is a clear line-of-sight between the expected positions of the ultrasound probe when it is on the targeted tissue volume and the position tracking module (i.e. a requirement specifically related to the use of visible detection technologies, such as is employed when an infrared camera tracks an visible register), that the that the position tracking module is connected to the data acquisition and display module/controller, and that the foot pedal is connected to the data acquisition and display module/controller.
[0165] Referring next to FIG. 11B, having completed the preliminary system set up and initialization steps, as represented by arrow 3118 to block 3120, the operator now proceeds to positioning the hand-held imaging probe at the starting position of the target tissue site on the patient (e.g., at the nipple of the right breast). Next, as represented by arrow 3122 to block 3124, the operator now proceeds to activate both the position tracking module and the associated data acquisition and display module/controller by depressing the foot pedal continuously during the entire period of each scan sequence performed using the hand-held ultrasound probe assembly with an audible tone issued and/or visible indicator confirming that the position sensing detection and recording function for the hand-held ultrasound probe assembly is currently active.
[0166] Once the position sensing detection and recording function has been activated, as represented by arrow 3126 to block 3128, the operator now proceeds to translate the hand-held imaging probe along the skin to begin the first of [i] scan sequences, SS[i,t] where i equals the number of scan sequences to be performed and t refers to the time period at which an ultrasound beam is emitted into the tissue and a returning acoustic signals are measured and recorded in what is referred to herein as an ultrasound scan frame. For the case of the first scan sequence (e.g., see scan sequence 80a in FIG. 10A), i is equal to 1.
[0167] Once the first scan sequence (i=1) is completed, as represented by arrow 3130 to block 3132, the operator releases the foot pedal to pause (i.e., to temporarily deactivate) the image recording function of the data acquisition and display module/controller. The time-stamped hand-held imaging probe position and computed orientation data acquired within the data acquisition and display module/controller is combined with the time-stamped ultrasound scan frames received from the ultrasound system to enable rapid computation of the image-to-image resolution of the scan sequence just completed. As represented by arrow 3134 to block 3136 as seen in FIG. 11B, the chord distances between any two successive scan frames are computed to determine if they are within pre-selected limits as illustrated with regard to FIG. 8B discussed above.
[0168] Still referring to FIG. 11B, an alternative embodiment of the present invention can be substituted at block 3136, which utilizes the imaging scan pixel density within the swept volume of the complete scan sequence as was described with regard to FIG. 9. In this alternative algorithm, the time-stamped hand-held imaging probe position and computed orientation data acquired within the data acquisition and display module/controller is combined with the time-stamped imaging scan frames received from the ultrasound system to enable rapid computation of the completeness of the scan sequence just completed. However, rather than computing the distances between successive scan frames, the pixel density within unit volumes within the swept volume are computed to determine if the computed pixel density is less than the preselected Minimum Pixel Density value.
[0169] Still referring to FIG. 11C, using either of the above two algorithms (i.e., scan frame distance based computations or volumetric pixel density within unit volumes of the swept volume), if the predetermined requirement is not met (i.e., maximum allowed distance between scan frames is exceeded or the minimum required pixel density is achieved for all unit volumes), then block 3140 is reached via arrow 3138. As seen in block 3140, an audible alarm and visual error message is issued to instruct the operator that the scan failed to comply with the minimum user requirements for frame-to-frame resolution. As represented by arrow 3139 and block 3141, the user is queried as to whether he or she wishes to accept this scan sequence, SS(i), which does not meet the user-defined minimum limits of frame-to-frame resolution. If the operator does not choose to accept the scan sequence SS(i), which does not meet the user-defined minimum limits of frame-to-frame resolution, then, as represented by arrow 3160 to block 3120, the operator repeats the scan sequence previously performed but determined to be incomplete due to the failure of the frame-to-frame resolution to meet the minimum user-defined requirements. If the user chooses to accept the scan sequence SS(i), which does not meet the user-defined minimum limits of frame-to-frame resolution, then block 3146 is reached via arrow 3143.
[0170] Still referring to FIG. 11C, using either of the above two algorithms (i.e., scan frame distance based computations or volumetric pixel density within unit volumes of the swept volume), if the user chooses predetermined requirement is met (i.e., maximum allowed distance between scan frames or minimum required pixel density), then block 3146 is reached via arrow 3144. If this is the first scan sequence (i.e., i=1), then the computation of distances between successive scan sequences (i.e., the maximum distance between ultrasound scan frames in scan sequence 80d and 80e as exemplified in FIG. 10B) is bypassed thereby proceeding to block 3164 via arrow 3148. In block 3164, the scan sequence index, is increased by the number 1. For this example description, the value of i was 1 and is now 2.
[0171] Referring now to FIG. 11D, as represented by arrow 3166 and block 3168, a computation is performed to determine if the scan sequence just completed is essentially the same as the initial scan sequence performed or, alternatively, if the last scan sequence has been performed for the target tissue volume. For the case of the human breast with successive radially oriented scan sequences progressing in a circular pattern as seen in FIG. 10A, the last scan sequence is obtained when the first scan sequence is essentially repeated. Alternatively, if the target tissue being scanned involves a rectangular pattern of successive scan sequences, the operator designates on the data acquisition and display module/controller that the last scan sequence has been performed. If the scan sequence just completed is not the last scan sequence required for the ultrasound examination, proceed as represented by arrow 3170 to block 3120 to initiate sequence of steps for next scan sequence.
[0172] Returning to block 3146 in FIG. 11C, if scan sequence i is greater than 1, then one of the above two algorithms (e.g., either computation of distance between two successive scan sequences or volumetric pixel density within unit volumes of the included volume between successive scan sequences) are used to determine the edge-to-edge coverage of the two successive scan sequences just completed as specified in block 3152. If the predetermined requirement is met (i.e., maximum allowed distance between the adjacent edges of scan frames in successive scan sequences is not exceeded or the pixel density in any unit volume is not less than the minimum required pixel density), then block 3164 is reached via arrow 3162. If the predetermined requirement is not met (i.e., maximum allowed distance between adjacent edges of scan frames in successive scan sequences is exceeded or the pixel density in any unit volume is less than the minimum required pixel density), then block 3156 is reached via arrow 3154. As seen in block 3156, an audible alarm and visual error message is issued to instruct the operator to determine that the coverage, as defined by the user-defined edge-to-edge spacing of adjacent edges in successive scan sequences, or the user-defined pixel density in any unit volume is less than the required pixel density, has not been met. Then block 3159 is reached via arrow 3157. The user is queried regarding whether he or she wishes to accept , scan sequence, SS(i), is to be accepted that the coverage, as defined by the user-defined edge-to-edge spacing of adjacent edges in successive scan sequences, or the user-defined pixel density in any unit volume is less than the required pixel density, has not been met. If the user chooses even though the coverage, as defined by the user-defined edge-to-edge spacing of adjacent edges in successive scan sequences, or the user-defined pixel density in any unit volume is less than the required pixel density, has not been met, to accept the scan sequence, SS(i), then block 3164 is reached via arrow 3163. If the user chooses not to accepted scan sequence, SS(i), because that the coverage, as defined by the user-defined edge-to-edge spacing of adjacent edges in successive scan sequences, or the user-defined pixel density in any unit volume is less than the required pixel density, then the scan sequence is repeated at a closer spacing relative to the prior scan sequence pathway. As represented in FIG. 11D, FIG. 11C, and FIG. 11B, arrow 3158 joins arrow 3160 to block 3120, wherein the operator repeats the scan sequence previously performed since it was determined to be incomplete due to regions of the target tissue not being included in the series of ultrasound scan frames just obtained.
[0173] Throughout the hand-held imaging procedure, the progression of scan sequences is shown on the screen of display 3 of the data acquisition and display module/controller 40 with the sequential scan index, i identified adjacent to each completed scan sequence in a manner similar to the illustration in FIG. 10A.
[0174] Returning to block 3174 of FIG. 11E, at the completion of the hand-held image scanning procedure and the verification that the target tissue ultrasound scans included all tissue within the target tissue volume (i.e., a complete diagnostic ultrasound scan was achieved), then the processing of the ultrasound scan frames is performed within the data acquisition and display module/controller. Arrow 3176 follows to block 3178, wherein the scanned images are arranged in a sequential order (i.e., progressing with elapsed time during procedure). In this step, the image data are captured and converted to a format that is easily stored and compatible with a viewer.
[0175] Referring to FIG. 11E and FIG. 11F, arrow 3190 joins block 3192 in which the user is queried regarding whether he or she wishes to view the scan sequences before processing the data and saving the procedure study. The viewer allows playback of the scanned images by the expert reviewer (e.g., radiologist) in a manner that is optimized for screening for cancers and other anomalies. If the user chooses to forego review, then arrow 3194 joins block 3196.
[0176] Still referring to FIG. 11F, if the user does choose to review the scans then arrow 3198 proceeds to 3200, in which the scan sequence images are displayed on a video monitor, such as a digital computer monitor. After review of the scan sequences, the system queries the user whether he or she wishes to accept the study. As depicted by arrow 3204 proceeding to join arrow 3194, which proceeds to block 3196, the images are processed. If the user chooses to not accept the images then a rescanning sequence is initiated as depicted by arrow 3208 proceeding to block 3210.
[0177] Still referring to FIG. 11F, the complete set of sequenced image frames are assigned patient, ultrasound instrument information, time, and location information as depicted in block 3196. The processed data is then stored on electronic media, such as a DVD ROM, disc drive, or flash memory drive). This process is depicted by arrow 3214 proceeding to block 3216. The DVD-ROM (or other suitable recording media) is physically transferred from the data acquisition and display module/controller to the expert (e.g., radiologist) for subsequent analysis and evaluation of the diagnostic ultrasound data with the confidence that the entire target tissue volume has been included in the supplied data recording. This last step defines the end of the diagnostic examination procedure for a particular patient. After the data is stored the image procedure is concluded as depicted by arrow 3218 proceeding to block 3220.
[0178] In addition to mapping the three-dimensional position of the pixels recorded from a set of two-dimensional images, the method, apparatus and system of some described embodiments performs a pixel density calculation to provide an objective characterization of the resultant image set to determine whether that spacing in the Z direction is sufficient to provide an accurate and complete three-dimensional image of the targeted tissue volume (e.g., the human female breast). By way of example, each of the pixels in each ultrasound scan-derived two-dimensional image, i are specified by a unique set of coordinates X{i,j} and Y{i,j} in two-dimensional space. When two adjacent two-dimensional images i and i+1 are combined to form a three-dimensional volume, then the position of each pixel is transformed into three-dimensional space and can be defined by the three Cartesian coordinates Xij, Yij and Zij.
[0179] Continuing with this this example and referring to FIG. 12A, assume that the overall volume circumscribed by any two adjacent two-dimensional scans is subdivided into smaller component volumes. By way of example, said smaller component volumes have two opposite square side faces measuring 2 mm2 mm and are defined, as seen in FIG. 12A, by the coordinates listed below. To facilitate the notation of XYZ coordinates at the boundaries of the example component volume, the physical spacing between sequential two-dimensional ultrasound scan images 2200 and 2201 has been significantly increased and is not drawn to scale relative to the overall dimensions of the ultrasound scan regions 2200 and 2201.
[0180] Coordinates of Square Side Faces on two-dimensional image 2200: [0181] X.sub.11Y.sub.11Z.sub.11 (1111), X.sub.12Y.sub.12Z.sub.12 (1112), X.sub.13Y.sub.13Z.sub.13 (1113), X.sub.14Y.sub.14Z.sub.14 (1114),
[0182] Coordinates of Square Side Faces on (i+1)th two-dimensional image 2201:
[0183] X.sub.21Y.sub.21Z.sub.21 (1121), X.sub.22Y.sub.22Z.sub.22 (1122), X.sub.23Y.sub.23Z.sub.23 (1123), X.sub.24Y.sub.24Z.sub.24 (1124)
[0184] Continuing with this example, the maximum spacing between the square 2 mm2 mm faces on adjacent two-dimensional images 2200 and 2201 for the first component volume is determined by comparing the following four distances along the Z axis: [0185] {Z.sub.11Z.sub.21}, {Z.sub.12Z.sub.22}, {Z.sub.13Z.sub.23}, {Z.sub.14Z.sub.24}
[0186] For this example, assume that the maximum distance between the four corners of the squares 2210 and 2211 in FIG. 12A is {Z.sub.14Z.sub.24}. Then the computed first component volume is the product of the unit area, A and the maximum spacing between the square faces 2210 and 2211 (2 mm2 mm for this example):
First Component Volume=A*{Z.sub.14Z.sub.24}EQ. 2
[0187] Continuing with this example and still referring to FIG. 12A, the First Component Volume Pixel Density for the First Component Volume is given by dividing the combined total number of pixels within the 2 mm2 mm areas, A on faces 2210 and 2211 on the two sequential two-dimensional images (e.g., 400 pixels on each image for a combined total of 800 pixels for two sequential images) by the First Component Volume given in Equation 3 as follows:
First Component Volume Pixel Density=(Total No. of Pixels in both Unit Areas)(First Component Volume) EQ. 3
[0188] Referring now to FIG. 1 and FIG. 12A and continuing with this example, the computed First Component Volume Pixel Density obtained in Equation 3 is compared with a predetermined Minimum Allowed Volumetric Pixel Density, which is selected to ensure that all regions within the targeted tissue volume are included in the ultrasound scan. The above example process is repeated (a) for each component volume defined by the boundaries of two sequential two-dimensional images 2200 and 2201 and (b) for all pairs of sequential two-dimensional images acquired during a screening procedure. If any sequential pair of two-dimensional ultrasound scans results in a Component Volume Pixel Density which is less than the Minimum Allowed Volumetric Pixel Density, then a warning is displayed on the data acquisition and display module/controller 40 so that the operator can repeat the ultrasound scan sequence just completed to increase the pixel density to meet the requirements of the predetermined Minimum Allowed Volumetric Pixel Density. By this process, a complete ultrasound screening is assured which includes all tissue volumes within the targeted tissue region.
[0189] Another embodiment of the present invention utilizes the geometrical relationship of any two sequential ultrasound scan images to reduce the number of component volumes that need to be analyzed to determine if [a] the maximum spacing limit between sequential ultrasound scan images has been exceeded and/or [b] the minimum pixel density in a component volume has not been achieved. Referring now to the example in FIG. 12B, two sequential two-dimensional ultrasound scan images 2200 and 2201 are shown in a spaced apart relationship with vector 2320 referring to the direction of transmitted and reflected ultrasound signals emanating from and received by the hand-held ultrasound probe. To facilitate the notation of XYZ coordinates at the boundaries of the example component volumes, the physical spacing between sequential two-dimensional ultrasound scan images 2200 and 2201 has been significantly increased and is not drawn to scale relative to the overall dimensions of the ultrasound scan regions 2200 and 2201.
[0190] Each two-dimensional ultrasound scan image, e.g., scan images 2200 and 2201, can be assumed to take the geometric form of a flat planar surface. In addition, since any two sequential two-dimensional ultrasound scan images are acquired within a very short time period, the boundary of the two-dimensional scan image (e.g., scan image 2200) is registered with and can be projected onto the boundary of the (i+1).sup.th two-dimensional scan image (e.g., scan image 2201). As a result of the registration of the boundaries of any two sequential two-dimensional ultrasound scan images and their planar geometry, only those component volumes located at the four corners of the pair of sequential two-dimensional ultrasound scan images, as seen in FIG. 12B need to be analyzed to determine if [a] the maximum spacing limit between sequential ultrasound scan images has been exceeded and/or [b] the minimum pixel density in a component volume has not been achieved.
[0191] By way of example and still referring to FIG. 12B, the Cartesian coordinates for component volume 2310a are shown in detail. Said component volume 2310a is comprised of two isosceles trapezoids 2300a and 2301a corresponding to end faces of the component volume 2310a located at one of four corners of the planar two-dimensional ultrasound scan images 2200 and 2201, respectively. The coordinates of 2300a are X.sub.28Y.sub.28Z.sub.28 (1128), X.sub.29Y.sub.29Z.sub.29 (1129), X.sub.26Y.sub.26Z.sub.26 (1126), X.sub.27Y.sub.27Z.sub.27 (1127). The coordinates of 2301a are X.sub.16Y.sub.16Z.sub.16(1116), X.sub.17Y.sub.17Z.sub.17(1117), X.sub.18Y.sub.18Z.sub.18(1118), X.sub.19Y.sub.19Z.sub.19 (1119), The Cartesian coordinates at each of the four corners of each of the isosceles trapezoids defining the component volume 2310a are used to determine the maximum spacing among the four Z-axis distances {Z.sub.16Z.sub.26, Z.sub.17Z.sub.27, Z.sub.18Z.sub.28, Z.sub.19Z.sub.29} between this pair of isosceles trapezoids 2300a and 2301a. This same procedure is next used to determine the maximum spacing between among the four Z-axis distances between pairs of isosceles trapezoids 2300b and 2301b, 2300c and 2301c and 2300d and 2301d corresponding to component volumes 2310b, 2310c and 2310d, respectively, as seen in FIG. 12B. These maxima for each of the four isosceles trapezoid pairs are next compared to determine which component volume among the four component volumes 2310a, 2310b, 2310c, or 2310d contains the maximum inter-scan image spacing along the Z-axis. That component volume 2310 containing the maximum inter-scan image spacing along the Z-axis is then used to determine if the requirements for maximum allowed inter-scan image spacing and/or minimum required pixel density have been achieved. If these predetermined requirements are not met, the operator is promptly alerted (e.g., with a visual cue indicating that the just completed ultrasound scan was not properly performed along with specified step(s) to correct the detected deficiency in the ultrasound scan.
[0192] By this novel method, the described embodiments greatly reduces the computation time required to assure that each subsequent two-dimensional ultrasound scan image meets the requirements for maximum allowed spacing and/or minimum required pixel density and that the operator can be alerted immediately after each scan path has been completed.
[0193] When the two-dimensional ultrasound scan-derived images are being presented in sequence, the greater the spacing between sequential scans (i.e., along the Z-axis as seen in FIG. 12A), the more compromised the ability of the clinician reviewing the screening images to accurately identify and characterize the lesion. By way of example, if the images are being presented at 15 frames per second, which is not unusual since the viewer will be accustomed to viewing a succession of still images as rapidly as 30 frames per second in standard video presentations, then a 1 mm spacing between two sequential, adjacent two-dimensional images would represent a presentation duration of 0.33 seconds of any unusual structure. In contrast, the case of a 3 mm spacing between two sequential, adjacent two-dimensional images would represent a presentation duration of only 0.07 seconds of any unusual structure due to the larger spacing between images. Since the brain has the capability to automatically detect unusual changes in the visual environment, a method, apparatus and system for displaying a normal image or a series of normal images, followed by an unusual image or a series of unusual images, will induce an involuntary recognition response (see Pazo-Alvarez, P., et. al., Automatic Detection of Motion Directed Changes in the Human Brain 2004. European Journal of Neuroscience; 19: 1978-1986). Studies with motion picture presentation suggest that frame rates slower than 15 frames/second are perceived less as motion, and more as individual images (see Read, P., et. al., Restoration of Motion Picture Film 2000. Conservation and Museology, Butterworth-Heinemann, ISBN 075062793X: 24-26). Thus, the presentation of a single frame of a random structure for the minimal period of time is more prone to being missed by the clinician/reviewer than the presentation of a series of sequential images of that structure over a longer period of time.
[0194] Minimizing the time duration of the reviewing process while maximizing the ability to recognize abnormalities within the video presentation of the ultrasound screening results is of primary importance to the clinician to avoid fatigue and maximize the efficient use of the clinician's time. The ultrasound scanning-derived image recording is time-based, with the images obtained in a temporally uniform manner This approach can present several problems. First, if the image spacing varies from one part of the scan to the next, then the ability to present the images in a spatially uniform manner is compromised. One portion may have images spaced on 0.01 mm centers while another may have them spaced on 1 mm centers. If the information recorded during the portion where images were recorded at 0.01 mm centers will take 10 times longer to display the same subset of swept volume of scan sequence as does the portion where images were recorded on 0.1 mm centers. When seeking to detect abnormalities on the order of 5 mm, it can be argued that there is no more real information presented in the 0.01 mm-center scans than there is in the 0.1 mm-center scans. The portion with the more closely spaced images may represent a reduction in viewer efficiency, not an increase in procedure efficacy.
[0195] Another embodiment of the present invention is seen in FIGS. 16A-16B and includes analyzing the complete data set from the ultrasound screening procedure to identify those two-dimensional scan images 400a-400o that are separated by a function of the translational speed of the ultrasound probe during the scanning procedure and the image recording rate of the data acquisition and control module. In one embodiment, those images that are separated by a Z-axis spacing close to the predetermined minimum spacing interval are saved while any additional two-dimensional scan images located between a pair of properly spaced two-dimensional scan images, consequently being separated by a spacing interval much less than the predetermined minimum spacing interval, are excluded from the final video presentation of the ultrasound scanning procedure. In the way of example, as described in FIG. 16A, if, because of variations in the translational speed during the scanning procedure, images are recorded at 0.0 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.5 mm, 3.7 mm, 4.0 mm, 4.3 mm, 4.7 mm, 5.0 mm, 5.5 mm, and 6.0 mm centers, and if the preferred image spacing is 1.0 mm, then only those images recorded at 0.1 mm, 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, and 6.0 mm will be displayed (that is, 400a, 400c, 400d, 400f, 400j, 400m, and 400o). The other images, 8 of the 15 recorded images, will not be displayed, reducing the viewing time by more than 50% (FIG. 16B). As a result of this embodiment of the present invention, the clinician is able to review the minimum number of images with essential visual information content. This method for post-processing the ultrasound screening data, with predetermined image spacing, provides a temporally and spatially uniform presentation.
[0196] Another embodiment of this present invention, also seen in FIGS. 16A-16B includes analyzing the complete data set from the ultrasound screening procedure to identify the spacing between each pair of adjacent scan images and to present those images in a spatially consistent manner, rather than a temporally consistent manner, as is the custom with most presentations of video images. The presentation of images is provided as a function of sweep volume and the dwell time for each image is determined as a function of the spacing between adjacent images. In the way of example, as described in FIG. 16A, if, because of variations in the translational speed during the scanning procedure, images are recorded at 0.0 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.5 mm, 3.7 mm, 4.0 mm, 4.3 mm, 4.7 mm, 5.0 mm, 5.5 mm, and 6.0 mm centers, and if the preferred image spacing is 1.0 mm/sec, then the dwell time, or the time the image is displayed before the next sequential image is displayed for 400a is 1.0 sec because the distance between 400a and 400b is 1.0 mm. The dwell time is calculated by dividing the distance between frames by the desired spatial presentation rate [1.0 mm/(1.0 mm/sec)]. In like manner the dwell time for 400b is 0.5 sec because the distance between 400b and 400c is 0.5 mm [0.5 mm/(1.0 mm/sec)]. In like manner the dwell times for 400c is 0.8 sec, for 400d is 0.2 sec, for 400e is 0.2 sec, for 400f is 0.3 sec, for 400g is 0.2 sec, for 400h is 0.3 sec, for 400i is 0.3 sec, for 400j is 0.4 sec, for 400k is 0.3 sec, for 400l is 0.5 sec, and for 400m is 0.5 sec. No dwell time is listed for 400o in this example because there is no sequential frame following 400o.
[0197] Referring to FIG. 1 and FIGS. 16A-16B, if the user varies his or her speed during the scan sequence, then there will be variable spacing in the images 400 that could be recorded, if those images 400 were recorded at regular time intervals. The position tracking module 22 and the data acquisition and display module/controller 40 poll the location of the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed at time intervals that are more frequent than the expected recording time interval to determine when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is at a location which would represent an acceptable spacing, regarding the previously recorded image 400. When the hand-held imaging probe is at the appropriate space, the data acquisition and display module/controller 40 will record an image. For example, in FIGS. 16A-16B, if images 400a-400o represent the location of the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed at 0.1 sec intervals, then the data acquisition and display module/controller 40 would only record an image at 0.0 seconds 400a (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is at its initial location), another image at 0.1 sec 400b (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is 1.0 mm past the previously recorded image, or at 1.0 mm), another image at 0.3 sec 400d (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is 1.0 mm past the previously recorded image, or at 2.0 mm), another image at 0.5 sec 400f (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is 1.0 mm past the previously recorded image, or at 3.0 mm), another image at 0.9 sec 400j (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is 1.0 mm past the previously recorded image, or at 4.0 mm), another image at 1.2 sec 400m (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is 1.0 mm past the previously recorded image, or at 5.0 mm), and another image 1.4 sec 400o (when the hand-held imaging probe 14 to which the plurality of position sensors 32a, 32b and 32c are affixed is 1.0 mm past the previously recorded image, or at 6.0 mm). The result would be 7 stored images which could be played back at almost half the time as would be required if all images which could have been recorded at regular time intervals were recorded.
[0198] Some embodiments described provide for the control of the imaging recording process by taking into consideration several factors during the scanning process. For example, these factors include image-to-image spacing, angular position of the probe, and scan-to-scan spacing. This allows the images to be recorded with uneven or non-constant spacing between one or more images. Uneven or non-constant spacing is often the result of variable translation speed as the operator moves the probe across a target region. Variable speed creates images of varying distances from one another. Some embodiments allow the operator to vary the speed of scanning while still ensuring adequate resolution and coverage of the scanned images. This can be accomplished by maintaining a minimum image-to-image distance, minimum scan-to-scan distance, or minimum pixel density.
[0199] As a further example, if the user varies his or her translational speed during a process so that the plurality of recorded images 400a-400o (see FIGS. 16A-16B), each having its own unique location identifier information, are spaced unevenly, the system and method can reduce the review time by calculating which of those images provide useful information and should be displayed during the review process, and which, because they are so closely spaced to the previous or following image, should not be displayed. By way of example, if the user wishes to review the 6 mm of tissue described in FIGS. 16A-16B, and the system has stored the 14 images 400a-400o, then the system and method may perform calculations using one or more microprocessors to determine which of the recorded images is closest to the desired spacing. Again by example, if the desired spacing is 1.0 mm, then only images 400a, 400b, 400d, 400f, 400j, 400m, and 400o are required to provide the desired resolution. The system can choose, through a logical argument which chooses only those images closest to the desired spacing parameters, to not display images 400c, 400e, 400g, 400h, 400i, 400k, 400l, and 400n.
[0200] If the user varies his or her translational speed during a process so that the plurality of recorded images 400a-400o, each having its own unique location identifier information, are spaced unevenly, the system and method can reduce the review time by calculating how long each of those images should be displayed during the review process, and which, because they are so closely spaced to the previous or following image, should not be displayed. By way of example, if the user wishes to review the 6 mm of tissue described in FIG. 16A, and the system has stored the 14 images 400a-400o described in FIG. 16A, then the system and method may perform calculations to determine how long to display each image, depending on the speed at which the reviewer wants to translate, from a virtual point of view, through the tissue. Again by example, if the desired spacing in FIG. 16 the space between image 400a and image 400b is 1.0 mm. If the reviewer wishes to review the images at 10 mm/sec, then the amount of time image 400a would be displayed before image 400b is displayed is 0.1 sec (1.0 mm/(10 mm/sec)). If the distance between image 400b and 400c is 0.5 mm, then the amount of time image 400b would be displayed before image 400c is displayed is 0.05 sec (0.5 mm/(10 mm/sec)). This process would be applied to all of the images so that the associated dwell time, or time for which each images is displayed is 400a=0.1 sec, 400b=0.05 sec, 400c=0.05 sec, 400d=0.08 sec, 400e=0.02 sec, 400f=0.02 sec, 400g=0.03 sec, 400h=0.02 sec, 400i=0.03 sec, 400j=0.03 sec, 400k=0.04 sec, 400l=0.04 sec, and 400m=0.05 sec. The total review time for this sequence is 0.56 sec. If the images were reviewed at 0.1 frames per second, as would be suggested from the spacing of images 400a and 400b, then the review time of the entire set of images would be 1.3 sec.
[0201] Other embodiments described provide for systems and methods for providing a speeded review time by limiting the number of images recorded. If an operator varies his or her speed during the scan process and the images are recorded at regular time intervals, then the recorded images will have irregular spacing. It is not necessary, however, that the system records the images at regular time intervals. The system may determine when to record the image by calculating where the image is in space, rather than as a function of time. By way of example, if the system recorded 19 images in one second, with the Z-plane location of those images being 0.0 mm recorded at 0.0 sec, 0.7 mm recorded at 0.1 sec, 0.9 mm recorded at 0.2 sec, 1.9 mm recorded at 0.3 sec, 2.5 mm recorded at 0.4 sec, 2.8 mm recorded at 0.5 sec, 3.6 mm recorded at 0.6 sec, 3.7 mm recorded at 0.7 sec, 4.0 mm recorded at 0.8 sec, 4.7 mm recorded at 0.9 sec, 5.1 mm recorded at 1.0 sec, 5.6 mm recorded at 1.1 sec, 6.6 mm recorded at 1.2 sec, 7.0 mm recorded at 1.3 sec, 7.6 mm recorded at 1.4 sec, 8.2 mm recorded at 1.5 sec, 8.5 mm recorded at 1.6 sec, 9.5 mm recorded at 1.7 sec, and 10.0 mm recorded at 1.8 sec, then the time to record those 19 images is 1.8 sec and the time to review them would be 1.8 sec at 10 frames per second. If the system only recorded images when they were at the desired spacing, then the review time and the image storage requirements would be lessened. By way of the above example, the probe is at 0.0 mm at 0.0 sec, it is at 1.0 mm at approximately 0.21 sec, it is at 2.0 mm at approximately 0.3167 sec, it is at 3.0 mm at approximately 0.5125 sec, it is at 4.0 mm at 0.8 sec, 5.0 mm at approximately 0.975 sec, 6.0 mm at approximately 1.15 sec, 7.0 mm at 1.3 sec, 8.0 mm at approximately 1.567 sec, 9.0 mm at approximately 1.65 sec, and 10.0 mm at 1.8 sec. Although it would take 1.8 sec to record these 11 images, they could be replayed in 1.0 sec, at 10 frames per second.
[0202] Since the scanning procedure is performed by hand, it is possible that the user, recording the images, may cover the same volume of tissue more than once, recording images for each scan. These overlapping scans can result in redundant images and reviewing those redundant images can increase the review time. In the most elementary description of this phenomenon, if the user scans the same region twice, then the second scan is redundant. Reviewing the second scan would only repeat previously presented information. With the exception of adding a second review, it would not serve a clinical purpose to review the second image. In some embodiments, a redundant image is an image for which all of the information contained within that image are contained in other images, or combinations of other images. In the way of example in FIGS. 17A and 17B, the two radial scans 1600 and 1602 of the breast begin at the periphery of the breast 60 and progress to the nipple 64. There is no overlap of scan information on the periphery, but overlap does occur as the scans approach the nipple 64. Any additional images which are recorded within the bounds of the two scans would be redundant. In this example, if a third scan 1608 were obtained between the first two, then, as with the other scans, there would be no overlap of information at the periphery of the breast 60. If a single image 1612 were captured within that portion of the scan, there may be some information that is redundant to other images, but there is other information that has not been imaged. Therefore, this image is not entirely redundant. If the operator continues with that scan, however, he or she will scan a region 1610 which has been completely scanned by the other scans 1600 and 1602. If a single image 1614 were captured in this region then all of the information contained therein would be redundant. In this example the region 1610 may contain a plurality of images, all of which are redundant. Significant review time may be saved by simply not reviewing these images. Some embodiments described provide for reducing review time by determining the overlap or redundancy between images in a scanned set of images. The scan set of images may then be modified to remove overlapping or redundant information. Determining redundancy or overlap may be accomplished by any of the methods described above, for example, by determine distances between pixels or comparing pixel density for scanned images.
[0203] In some embodiments, the phrase uniform temporal display or review refers broadly to modifying a scan sequence such that the review time satisfies a predetermined time regardless of the number of images in the scan sequence. In some cases, this is accomplished by allocating dwell times or review times for each image in the scan sequence. For example, a scan sequence having 10 images may have a predetermined review time of 10 seconds for all 10 images. However, the review time allocated to each image within the 10 image scan sequence can vary from image to image. Some images may be assigned 1.0 second dwell times. Other images may be apportioned 0.75 second dwell times. Such allotment may be a function of the relative spacing between the images. In some embodiments, uniform temporal display or review indicates that the overall total time for review of the scan sequence is substantially the same regardless of the individual dwell times or review times for each discrete image within the scan sequence.
[0204] In some embodiments, the phrase uniform spatial display or review refers broadly to modifying a scan sequence such that the relative spacing between discrete images within a scan sequence is substantially the same. For example, a scan sequence may have recorded images at 0 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.2 mm, 2.5 m, and 3.0 mm. Such a scan sequence may be modified to have uniform spatial display or review by removing images that do not have a preferred relative spacing. The relative spacing may be for example 1.0 image-to-image spacing. In this case, the recorded images for review would not include 1.5 mm, 2.2 mm, and 2.5 mm. The modified scan sequence would provide for a uniform spatial display or review.
[0205] In some embodiments, the review images may exhibit uniform spatial-temporal display or review having both uniform spatial and uniform temporal characteristics or some combination within the review scan sequence images.
[0206] Some embodiments provide for methods, systems, or devices that allow the reviewer to mark or otherwise annotate the images for review. In some cases, the annotation or marking indicates a location on the scanned image that may need to be reviewed further. In other embodiments, the marked section in the image may indicate the site of a suspicious lesion or structure, e.g., potential tumor.
[0207] Another embodiment of the present invention is seen in FIG. 13 wherein optical recognition is used for continuously detecting the position and orientation of a hand-held ultrasound probe assembly 230 in place of the use of electromagnetic radiofrequency position sensors as described in the preceding specification related to FIGS. 1 through 9 and FIG. 11. As described previously with regard to FIGS. 1 through 9 and FIG. 11, the optical recognition based position and orientation detection method, apparatus and system is used to accurately determine the position of each two-dimensional ultrasound scan image and, thereby, the temporal position of each pixel within each two-dimensional ultrasound scan image.
[0208] Referring to FIG. 13, two principal subsystems are illustrated. A first subsystem is the diagnostic ultrasound system 12, which includes ultrasound monitor console 18, display 17, hand-held ultrasound probe 214 and connecting cable 16. A second system (referred to hereinafter as the Optically Based Optically Based Ultrasound Scan Completeness Auditing System), is represented in general at 218. The Optically Based Ultrasound Scan Completeness Auditing System 218 comprises a data acquisition and display module/controller 240 including microcomputer/storage/DVD ROM recording unit 241, display 213 and foot pedal control 212. Foot pedal 212 is connected to microcomputer/storage/DVD ROM recording unit 241 via cable 215 and removably attachable connector 13. The Optically Based Ultrasound Scan Completeness Auditing System 210 also comprises position-tracking system 220, which includes position tracking module 222 and two or more, preferably three or more cameras 235 (e.g., infrared cameras). In addition, the Optically Based Ultrasound Scan Completeness Auditing System 210 also comprises two or more optically unique (i.e., uniquely identifiable) position markers 232 affixed to the hand-held ultrasound probe 214. Said two or more, preferably three or more, cameras may operate in the visible spectrum or infrared spectrum.
[0209] By way of example and still referring to FIG. 13, four infrared cameras 235a-235d are shown at predetermined fixed positions whose fields of view include the hand-held ultrasound probe assembly 230 including six optically unique position markers with three position markers 232a-232c visible on the front side of hand-held ultrasound probe assembly 230 (232d-232f on back side of hand-held ultrasound probe assembly 230 but not shown). Said infrared cameras removable connected to position tracking module 222 at connectors 236a-236d via cables 243a-234d. Said optically based position detection method, system and apparatus is capable of obtaining 100 position measurements per second at a camera-to-object distance of up to 3 meters with position accuracies to within less than 1 millimeter. See, for example, an off-the-shelf optically based position detection device, Spotlight Tracker, manufactured by Ascension Technology Corporation, Burlington, Vt.
[0210] Still referring to FIG. 13, diagnostic ultrasound system 12 is connected to data acquisition and display module/controller 240 via data transmission cable 46 to enable each frame of ultrasound data (typically containing about 10 million pixels per frame) to be received by the microcomputer/storage/DVD ROM recording unit 241 at the end of each individual scan, which is completed about every 0.1 to 0.02 seconds. Cable 248 is removably attached to microcomputer/storage/DVD ROM recording unit 241 of data acquisition and display module/controller 240 with removably attachable connector 245 and is removably connected to diagnostic ultrasound system 12 with connector 47. The successive scans associated with the diagnostic ultrasound procedure are stored and subjected to computational algorithms to assess completeness of the diagnostic ultrasound scanning procedure as described in greater detail in the specifications which follow.
[0211] Still referring to FIG. 13, hand-held ultrasound probe position tracking module 222 is connected to data acquisition and display module/controller 240 via data transmission cable 248 wherein cable 248 is removably attached to microcomputer/storage/DVD ROM recording unit 241 of data acquisition and display module/control 240 with connector 245 and is removably connected to position tracking module with connector 249. Hand-held ultrasound probe assembly 230 seen in FIG. 1 includes, by way of example, six optically unique position markers 232a-232c (232d-232f on back side of hand-held ultrasound probe assembly 230 and not shown), which are affixed to ultrasound hand-held probe 214. As seen in the example arrangement shown in FIG. 13, four infrared cameras 235a-235d are positioned at known locations around the perimeter and in unobstructed view of the hand-held ultrasound probe assembly 230. Optical recognition and vectoring software contained within the position-tracking module 222 provides the exact position and orientation of the hand-held ultrasound probe assembly 230 preferably at time intervals of 0.05 seconds and more preferably of at time intervals of 0.01 seconds.
[0212] Referring now to FIGS. 14A-14C and by way of example, six optically unique position markers, 232a-232c (232d-232f on back side of hand-held ultrasound probe assembly 230 and not shown) are affixed to the hand-held ultrasound probe 214 as described now in greater detail. These optical position markers can be differentiated from each other by the geometry of the reflective pattern, the reflective wavelength, or a combination therein. In some embodiments, the optical markers can be affixed to the probe assembly 214 by means of an adhesive bond. In another embodiment of a hand-held probe assembly 230, a hand-held ultrasound probe 214 is enclosed within first and second clamshell type support members 242 and 244, respectively.
[0213] Continuing with this exemplary embodiment and referring to FIGS. 14A-14C, three optically unique position markers 232a-232c are affixed to the exterior surface of first support member 242. In addition, three optically unique position markers 232d-232f (not shown) are affixed to the exterior surface of second support member 244. The number of sensors is only limited by the ability to generate optically unique geometries and colors and the amount of surface area on the probe. Referring to FIG. 14B, three cameras 271a-271c individually locate three markers 232b, 232h, 232i. Since the locations of the markers 232b, 232h, 232i relative to the geometry of the probe assembly 230 are known, the location and calculated orientation of the probe assembly 230 can be determined. The location and calculated orientation of the probe assembly 230 can be determined even if one or more or all of the original markers 232b, 232h, 232i are obscured from the line-of-site of the cameras 271a-271c. As depicted in FIG. 14C, this may be accomplished as the cameras 271a-272c can locate an additional marker such as 232j, 232k for each marker that is obscured 232b, 232i. In some embodiments, the location of three markers 232h, 232j, 232k are known and since the location of these three markers 232h, 232j, 232k are also known relative to the probe assembly 230, the location and the orientation of the probe assembly 230 may be determined. In other embodiments, any number or subset of a plurality of sensors/markers may be used to determine location and orientation of the probe assembly.
[0214] Another embodiment of the present invention is further illustrated in an exploded view of the hand-held probe assembly 230 as seen in FIG. 15. Said first support member 242 includes the aforementioned three optically unique position markers 232a-232c. First support member 242 also incorporates extension ears 236a and 236b, each with a drilled hole to enable secure mechanical attachment to second support member 244. Said second support member 244 likewise incorporates extension ears 238a and 238b, each with a drilled hole which matches drilled holes in first support member to enable secure mechanical attachment to second support member 242 using screws 239a and 239b, respectively. First and second support members may be manufactured using metal, metal alloy or, preferably, a rigid plastic material. The interior contours and dimensions of the first and second support members 242 and 244 are designed to match the particular contour and dimensions of the off-the-shelf hand-held ultrasound probe being instrumented with the optically unique position markers 232a-232c. Accordingly, the contours and dimensions of the first and second support members 242 and 244 will vary according to the hand-held ultrasound probe design. The exact location of the optically unique position markers 232a-232c relative to the ultrasound transducer array at the end face of the hand-held ultrasound probe (not shown) will accordingly be known for each set of first and second support members since they are designed to attached to and operate in conjunction with a specific hand-held ultrasound probe.
[0215] Returning to FIG. 2, the typical dimensions of a hand-held ultrasound probe 14 are provided below: [0216] W1=1.5 to 2.5 inches [0217] L1=3 to 5 inches [0218] D1=0.5 to 1 inch
[0219] Accordingly, as specified in the previous paragraph, the first and second support members 242 and 244 are sized to correspond to the particular contour and dimensions of a specific hand-held ultrasonic probe design. For the case of injection-molded plastic, e.g., a biocompatible grade of polycarbonate, the inner dimensions of said first and second support members 242 and 244 are designed to closely match the outer dimensions of the hand-held ultrasound probe 214. The wall thickness of the injection molded plastic support members 242 and 244 is preferably in the range from 0.05 to 0.10 inch.
[0220] Although certain location and motion recognition methods have been described (e.g. FIG. 13), it can be appreciated that any location and motion recognition methods, software, devices, or systems can be used with the described embodiments. For example, sonar, radar, microwave, or any motion or location detection means may be employed.
[0221] Furthermore, a position sensor may not be a separate sensor added to the imaging device but may be a geometric or landmark feature of the imaging device, for example, the corners of the probe. In some embodiments, the optical, infrared, or ultraviolet cameras could capture an image of the probe and interpret the landmark feature as a unique position on the imaging device. Moreover, in some embodiments, sensors may not need to be added to the imaging device. Rather, location and motion detection systems can be used to track the position of the imaging device by using geometric or landmark features of the imaging device. For example, a location system may track the corners or edges of an ultrasound imaging probe while it is scanned across a target tissue.
[0222] According to the specifications of embodiments of the present invention, either the electromagnetic radiofrequency-based method, apparatus and system or the optical recognition-based method, apparatus and system can be used to detect the position of the hand-held ultrasound probe at all time points corresponding to the time of any two-dimensional ultrasound scan image. This position and orientation data is used to compute the maximum distance between sequential two dimensional ultrasound scan images to determine if predetermined maximum spacing limits are exceeded or predetermined pixel density limits are not achieved. If any predetermined requirements are not achieved, the ultrasound screening operator is alerted with a visual display identifying that the scan just completed [a] was performed with an excessive spacing relative to the previous scan in the sequence and/or [b] was performed a rate of translation and/or rotation that was too fast to meet pixel density or spacing requirements.
[0223] Images may be retrieved and stored in a variety of manners. By way of example and as is one of the teachings in FIG. 1, the microprocessor/storage/DVD ROM recording unit 41 of the data acquisition and display module/controller 40 could be a standard computer with a video frame grabber card. The data transmission cable 46 could connect to the video output of the hand-held imaging system 12 and record discrete images in a wide variety of formats including, but not restricted to JPG, BMP, PNG. Each image would be stored with an information header containing, but not restricted to, the location of the image at the time it was recorded. The individual images could be stored in sets of scan tracks, and the scan tracks could be stored as a complete examination, or the images could be stored using another data management protocol. The resulting set of images could be comprised of several thousand individual, discrete images.
[0224] Once the set of images is compiled, it may be stored as a set, along with the location information and other information, such as patient identification, etc., to a portable storage device 9, such as a DVD ROM, portable hard drive, network hard drive, cloud-based memory, etc. These data may be viewed on the data acquisition display module/controller 40, or an external computer equipped with software designed to review the image data.
[0225] In yet another embodiment of the present invention, an optical image projector can be included in either the Ultrasound Scan Completeness Auditing System or the Optically Based Ultrasound Scan Completeness Auditing System to superimpose optical information on the surface of the targeted tissue (e.g., the human female breast). Said optical information may, by way of example, include the ultrasound scan path(s) that need to be repeated due to excessive inter-scan distances, inadequate overlap and/or excessive scanning translation speed and/or rate of rotation. Said optical information can thereby guide the conduct of additional two-dimensional ultrasound scans to overcome any determined deficiencies.
[0226] Since certain changes may be made in the above-described system, apparatus and method without departing from the scope of the invention herein involved, it is intended that all matter contained in the description thereof or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The disclosed invention advances the state of the art and its many advantages include those described herein.
[0227] As for additional details pertinent to the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms a, and, said, and the include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as solely, only and the like in connection with the recitation of claim elements, or use of a negative limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed.
