Breast ultrasound scanning template
Apparatus and related methods for facilitating volumetric ultrasonic scanning of a breast are described. In one preferred embodiment, a generally cone-shaped radial scanning template having a vertex and a wide opening angle is provided, the radial scanning template having a slot-like opening extending outward from the vertex through which an ultrasound transducer scans the breast as the radial scanning template is rotated. In another preferred embodiment, a flexible membrane for compressing a skin surface of the breast is provided, the flexible membrane being mounted on a mechanical assembly such as a roller assembly to form a slot-like opening through which an ultrasound transducer directly contacts the skin surface, the flexible membrane rising and falling relative to the skin surface but not moving laterally as the slot-like opening and ultrasound transducer move laterally across the compressed breast, whereby stabilization of the breast and direct transducer-skin contact are concurrently achieved.
This application claims the benefit of U.S. Provisional Application No. 60/713,282, filed Sep. 1, 2005, which is incorporated by reference herein.
FIELDThis patent specification relates to medical imaging. More particularly, this patent specification relates to breast ultrasound scanning.
BACKGROUNDVolumetric ultrasound scanning usually involves the movement of an ultrasound transducer relative to a tissue sample and the processing of resultant ultrasound echoes to form a data volume representing at least one acoustic property of the tissue sample. Volumetric ultrasound scanning of the breast has been proposed as a complementary modality for breast cancer screening as described, for example, in the commonly assigned US 2003/007598A1, which is incorporated by reference herein. The commonly assigned WO 2004/030523A2, which is incorporated by reference herein, describes a full-field breast ultrasound (FFBU) scanning apparatus that compresses a breast along planes such as the craniocaudal (CC) plane, the mediolateral oblique (MLO) plane, etc., and ultrasonically scans the breast. One side of an at least partially conformable, substantially taut membrane or film sheet compresses the breast. A transducer translation mechanism maintains an ultrasound transducer in contact with the other side of the film sheet while translating the ultrasound transducer thereacross to scan the breast.
Other FFBU scanning devices that compress the breast in other directions, such as in generally chestward or “head-on” directions, are described in one or more of the following commonly assigned applications, each of which is incorporated by reference herein: U.S. Ser. No. 60/565,698 filed Apr. 26, 2004; U.S. Ser. No. 60/577,078 filed Jun. 4, 2004; U.S. Ser. No. 60/629,007 filed Nov. 17, 2004; WO 2005/104729 A2; and WO 2005/120357 A1. It would be desirable to facilitate ultrasound scanning of a breast in a manner that promotes volumetric completeness and good image quality while also promoting patient comfort and clinical efficiency.
WO 03/103500 discusses the use of a tissue molding element having a hole through which an ultrasonic transducer scans the breast as the tissue molding element is rotated. However, in comparison to one or more of the preferred embodiments described herein, the device(s) discussed in WO 03/103500 bring about one or more shortcomings in relation to volumetric completeness, image quality, patient comfort, and/or clinical efficiency. Other issues arise as would be readily apparent to one skilled in the art in view of the present disclosure.
SUMMARYAn apparatus and related methods for ultrasonically scanning a tissue sample are provided, the apparatus comprising an ultrasound transducer and a radial scanning template that compresses the breast in a generally chestward direction, the radial scanning template being generally cone-shaped and having a vertex and an opening angle. The radial scanning template has a slot-like opening extending outward from the vertex through which the ultrasound transducer scans the breast as the radial scanning template is rotated. According to one preferred embodiment, the opening angle is substantially greater than ninety degrees. In another preferred embodiment, the opening angle is greater than 120 degrees, and in still another preferred embodiment, the opening angle is greater than 135 degrees.
Generally speaking, a wider opening angle substantially greater than 90 degrees promotes improved flattening of the breast tissue toward the chest wall, thereby reducing the required scan depth. This allows for higher ultrasound scan frequencies to be used (e.g., 10 MHz-15 MHz) which, in turn, results in improved image quality. The described radial scanning template is particularly effective for ultrasonically scanning the beast of a supine patient, although application to other patient positions (e.g., prone, upright) is within the scope of the preferred embodiments.
In one preferred embodiment, the center of rotation of the radial scanning template is located at the vertex, and the vertex is positioned atop the breast nipple. Optionally, a central opening is provided that receives the nipple of the breast such that the nipple surface is not compressed to the same extent as the remainder of the skin surface.
Preferably, the radial scanning template comprises a material that is semi-rigid, or substantially rigid, and that is optically translucent for facilitating breast positioning and scanning. In one preferred embodiment, the ultrasound transducer directly contacts a skin surface of the breast while scanning the breast through the slot-like opening. In another preferred embodiment, a membrane extends across the slot-like opening, and the ultrasound transducer scans the breast through the membrane. The membrane may comprise a thin film sheet, such as Mylar or Melinex, that is nonporous to ultrasound coupling agent. Alternatively, the membrane may comprise a fabric material porous to ultrasound coupling agent.
According to one preferred embodiment, there is only a single ultrasound transducer and only a single slot-like opening in the radial scanning template. The radial scanning template is rotated by 360 degrees plus an overlap angle during the breast ultrasound scan, the overlap angle being in a range of 5 to 45 degrees. Thus, breast tissue within the overlap angle is scanned twice. The dual scans can be used to reduce a discontinuity in the resulting volumetric representation of the breast associated with the start-stop location of the radial scan.
According to another preferred embodiment, a plurality of ultrasound transducers and a corresponding plurality of slot-like openings are provided. In general, where there are N transducers, a full volumetric scan can be achieved by rotating the radial scanning template by 360/N degrees, plus an overlap angle if desired.
In one preferred embodiment, at least two of the ultrasound transducers have different lengths corresponding to different vertex-to-base distances around the radial scanning template. Each ultrasound transducer scans a different coronal sector of the breast. In one example, a longer of the ultrasound transducers can be responsible for the coronal sector of the breast that is nearest the axilla, which usually extends farther out from the nipple than other sectors. In another preferred embodiment, one or more of the ultrasound transducers can be tilted at different angles from a normal to the coronal plane for facilitating tilt-based compounding and/or volumetric completeness of the scan.
In other preferred embodiments, various parameters associated with the multiple ultrasound transducers can be varied, and the resulting scans can be compounded in various advantageous ways. Examples of parameters that can be varied among different transducers includes, but is not limited to, scan frequency, tilt angle, elevation beamwidth, scan mode (e.g., B-mode, harmonic, Doppler), in-plane acoustic interrogation angles, and different in-plane multi-angle compounding schemes.
In one preferred embodiment, a scanning surface of an ultrasound transducer has fewer rows of transducer elements nearer the vertex and more rows of transducer elements farther from the vertex. This can promote more uniform voxel elements in the volumetric ultrasound scan and faster scanning intervals. In another preferred embodiment, the ultrasound transducer comprises a single linear array of transducer elements, but different subsets of the transducer elements are fired at different rotational positions, with transducer elements farther from the vertex being fired at more rotational positions than transducer elements nearer to the vertex. This can likewise promote more uniform voxel elements in the volumetric ultrasound scan and faster scanning intervals.
In one preferred embodiment, the slot-like opening and the ultrasound transducer both extend along substantially all of a vertex-to-base length of the radial scanning template, such that a complete volumetric scan can be achieved in a single 360-degree rotation. In another preferred embodiment, the ultrasound transducer extends only along a portion of the slot-like opening and is slidably translated along the slot-like opening during multiple rotations of the radial scanning template for achieving volumetric completeness of the scan.
In another preferred embodiment, an apparatus for ultrasonically scanning a breast is provided, comprising a plurality of ultrasound transducers and a scanning template comprising a generally cone-shaped surface that compresses the breast in a generally chestward direction. The generally cone-shaped surface has a vertex and defines a plurality of slot-like openings extending outward from the vertex through which the plurality of ultrasound transducers, respectively, scan the breast as the scanning template is rotated.
In another preferred embodiment, an apparatus for ultrasonically scanning a breast is provided, comprising an ultrasound transducer having a scanning surface, and a compressor having a compressive surface that compresses a skin surface of the breast, wherein a slot-like opening is formed in the compressive surface through which the scanning surface of the ultrasound transducer directly contacts the skin surface. The compressor is configured such that the slot-like opening moves laterally over the compressed skin surface in conjunction with the ultrasound transducer as the ultrasound transducer is moved thereacross to ultrasonically scan the breast. Thus, both breast compression and direct skin contact are advantageously provided during the ultrasound scan. In one example, the compressive surface comprises a flexible membrane and a roller assembly causing the membrane to rise and fall relative to the skin surface, but not to move laterally relative to the skin surface, as the ultrasound transducer is moved laterally across the compressed breast. In one preferred embodiment, the membrane comprises a thin film sheet that is nonporous to ultrasound coupling agent, while in another preferred embodiment the membrane comprises a fabric material porous to ultrasound coupling agent.
DETAILED DESCRIPTION
Also shown in
Preferably, the support arm 106 is configured and adapted such that the overall compression/scanning assembly 112-120 is either (i) neutrally buoyant in space, or (ii) has a light net downward weight (e.g., 2-3 pounds) for breast compression, while allowing for easy user manipulation. Optionally, the support arm 106 may comprise potentiometers (not shown) to allow position and orientation sensing for the overall compression/scanning assembly 112-120, or other types of position and orientation sensing (e.g., gyroscopic, magnetic, optical, radio frequency (RF)) can be used.
Within frame 104 may be provided a fully functional ultrasound engine for driving an ultrasound transducer and generating volumetric breast ultrasound data from the scans in conjunction with the associated position and orientation information. The volumetric scan data can be transferred to another computer system for further processing using any of a variety of data transfer methods known in the art. A general purpose computer, which can be implemented on the same computer as the ultrasound engine, is also provided for general user interfacing and system control. The general purpose computer can be a self-contained stand-alone unit, or can be remotely controlled, configured, and/or monitored by a remote station connected across a network.
In one preferred embodiment, the ultrasound transducer 114 is supported and actuated independently from the radial scanning template 112. In another preferred embodiment, the ultrasound transducer 114 is integral with, clipped to, or otherwise fused with the radial scanning template 112 for joint support and/or actuation.
With reference to
In one preferred embodiment, the radial scanning template 112 is formed from a translucent, semi-rigid material having mechanical properties similar to those of 40-mil polycarbonate plastic, 40-mil polystyrene plastic, or an equivalent amount of polyethylene terephthalate (PETE) plastic. In this embodiment, there is some amount of “give” or flexibility to the template 102 providing at least some degree of comfort to the patient as well as adaptability to differently-shaped breasts, while at the same time providing for substantial stabilization of the breast tissue for reliable volumetric imaging of the breast. In another preferred embodiment, the material for template 102 comprises a translucent, substantially rigid material such as 140-mil glass, 140-mil acrylic, or 140-mil polycarbonate plastic. Preferably, a lower surface of the radial scanning template 112 makes a slippery contact with the skin surface in the presence of an ultrasound couplant so that rotation is easily achieved even when the breast is under some degree (e.g., 4-12 lbs.) of downward compression. Despite the slippery contact with the breast, stabilization is provided by virtue of the generally conical shape of the radial scanning template 112. Preferably, a curled lip (not shown) is provided around the base 304 to prevent skin cuts, similar to the way curled upper lips are provided on many polystyrene and PETE plastic drinking cups.
In the particular embodiment of
In one preferred embodiment, the membrane 710 comprises a thin film sheet, such as Mylar or Melinex, that is nonporous to ultrasound coupling agent. In another preferred embodiment, the membrane can be vented (e.g., punctured or stamped with a pattern of small holes) for allowing porosity relative to the coupling agent, which can be advantageous in that air bubbles are reduced. Examples of other materials that can be used for the vented or non-vented membrane include, but are not limited to, polypropylene, polyester, polyethylene, PTFE, PET, paper, Kevlar, metal, and epoxy-fiber composite materials.
In another preferred embodiment, the membrane 710 comprises a fabric material porous to ultrasound coupling agent, which can be advantageous in that air bubbles are reduced. As used herein, fabric refers generally to a material structure of interconnected parts, such as can be formed by knitting, weaving, or felting natural or synthetic fibers, assembling natural or synthetic fibers together into an interlocking arrangement, fusing thermoplastic fibers, or bonding natural or synthetic fibers together with a cementing medium, and further refers to materials having similar textures or qualities as those formed thereby, such as animal membranes or other naturally occurring substances having fabric-like properties (either inherently or by processing), and such as materials generated by chemical processes yielding fabric-like webbings. One particularly suitable material for the taut fabric sheet comprises a polyester organza material having a filament diameter of about 40 microns and a filament spacing of about 500 microns. However, the fabric membrane may comprise any of a variety of other fabrics that are substantially inelastic and generally porous to ultrasound couplants without departing from the scope of the present teachings. Examples include, but are not limited to, polyester chiffon fabrics and cloth fabrics comprising straight weaves of substantially inelastic fibers. Where the weave is particularly tight (for example, the cloth used in men's dress shirts or the cloth used in many bed sheets), porosity can be achieved by perforating the cloth or otherwise introducing irregularities that allow the ultrasound couplant to soak or seep through.
In another preferred embodiment, the radial scanning template 1202 is rotated by the full 360 degrees plus overlap angle, with the different ultrasound transducers being differently configured with respect to at least one imaging parameter. The resultant volumetric scans are then compounded in any of a variety of advantageous ways. Parameters that may be varied among the transducers include, but are not limited to, scan frequency, tilt angle, elevation beamwidth, scan mode (e.g., B-mode, harmonic, Doppler), in-plane acoustic interrogation angles, and different in-plane multi-angle compounding schemes.
More generally, “N” slot-like openings can be provided and the radial scanning template can be rotated by 360/N degrees plus an overlap angle. Alternatively, the radial scanning template is rotated by the full 360 degrees plus overlap angle and the “N” resultant scans compounded in advantageous ways.
The obtained ultrasound scans can be advantageously used in a variety of ways in accordance with the preferred embodiments. For example, it has been found that the acquired volumetric data is particularly advantageous in generating SOMOGRAM™ representations of the breast, SOMOGRAM™ being a trademark of U-Systems, Inc., of San Jose, Calif. Various compounding schemes for data obtained from transducers having at least one different imaging parameter can be used, including compounding on a per-slice basis, compounding on a per-volume basis, and compounding on a per-SOMOGRAM™ basis.
Whereas many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description, it is to be understood that the particular embodiments shown and described by way of illustration are in no way intended to be considered limiting. By way of example, it is to be appreciated that any of a variety of different frame assemblies can be used that position, compress, rotate, and otherwise manipulate the scanning template, whether the scanning template is permanently used and re-used for different patients or is disposable for each patient, without departing from the scope of the present teachings. Moreover, in one or more alternative preferred embodiments, the basic profile of the radial scanning template can be dome-shaped, ellipsoidally shaped, etc., rather than strictly cone-shaped as indicated in the attached drawings. The scanning surface of the ultrasound transducer can be arced in a similar manner, if desired. Therefore, reference to the details of the embodiments are not intended to limit their scope.
Claims
1. An apparatus for ultrasonically scanning a breast, comprising:
- an ultrasound transducer; and
- a radial scanning template that compresses the breast in a generally chestward direction, the radial scanning template being generally cone-shaped and having a vertex and an opening angle, the radial scanning template having a slot-like opening extending outward from the vertex through which the ultrasound transducer scans the breast as the radial scanning template is rotated;
- wherein said opening angle is substantially greater than ninety degrees.
2. The apparatus of claim 1, wherein said opening angle is greater than 135 degrees.
3. The apparatus of claim 1, said radial scanning template including a membrane extending across said slot-like opening, said ultrasound transducer scanning the breast through said membrane.
4. The apparatus of claim 1, said ultrasound transducer being a sole ultrasound transducer, wherein said radial scanning template is rotated by 360 degrees plus an overlap angle during said scan of the breast, said overlap angle being in a range of 5 to 45 degrees, whereby breast tissue within the overlap angle is scanned twice for facilitating reduction of a discontinuity in a resulting volumetric representation of the breast.
5. The apparatus of claim 1, said ultrasound transducer being a first ultrasound transducer and said slot-like opening being a first slot-like opening, said apparatus further comprising (N−1) additional ultrasound transducers, N≧2, said radial scanning template defining (N−1) additional slot-like openings through which said (N−1) additional ultrasound transducers, respectively, scan the breast as the radial scanning template is rotated by at least 360/N degrees during said scan of the breast.
6. The apparatus of claim 5, said radial scanning template having an oblong base, at least two of said ultrasound transducers having different lengths corresponding to different vertex-to-base distances around said base, wherein a longer of said at least two ultrasound transducers corresponds to an axillary section of the breast.
7. The apparatus of claim 5, wherein at least two of said ultrasound transducers differ in at least one characteristic selected from the group consisting of: ultrasonic scan frequency, tilt angle from a plane that is perpendicular to a coronal plane, ultrasound scanning mode, and beamsteering angle.
8. The apparatus of claim 1, wherein said vertex of said radial scanning template is positioned atop a nipple of the breast, and wherein a center of rotation of said radial scanning template is located at said vertex.
9. The apparatus of claim 1, wherein said radial scanning template is at least slightly arced in a manner that causes the general cone shape thereof to also at least partially resemble a general dome shape, and wherein said ultrasound transducer has a corresponding arc-shaped scanning surface.
10. The apparatus of claim 1, wherein a scanning surface of the ultrasound transducer has fewer rows of transducer elements nearer said vertex and more rows transducer elements farther from said vertex for promoting at least one of voxel element uniformity and faster scanning intervals.
11. The apparatus of claim 1, the ultrasound transducer comprising a linear array of transducer elements, wherein transducer elements farther from said vertex are fired at more rotational positions than transducer elements nearer to said vertex during said scan of the breast for promoting at least one of voxel element uniformity and faster scanning intervals.
12. An apparatus for ultrasonically scanning a breast, comprising:
- a plurality of ultrasound transducers; and
- a scanning template comprising a generally cone-shaped surface that compresses the breast in a generally chestward direction, the generally cone-shaped surface having a vertex and defining a plurality of slot-like openings extending outward from the vertex, said plurality of ultrasound transducers scanning the breast through respective ones of the slot-like openings as the scanning template is rotated to ultrasonically scan the breast.
13. The apparatus of claim 12, said scanning template having an opening angle that is greater than 135 degrees.
14. The apparatus of claim 12, further comprising a plurality of membranes extending across respective ones of said slot-like openings, said ultrasound transducers scanning the breast through corresponding ones of said membranes.
15. The apparatus of claim 12, said scanning template having an oblong base, at least two of said ultrasound transducers having different lengths corresponding to different vertex-to-base distances around said base, wherein a longer of said at least two ultrasound transducers corresponds to an axillary section of the breast.
16. The apparatus of claim 12, wherein at least two of said ultrasound transducers differ in at least one characteristic selected from the group consisting of: ultrasonic scan frequency, tilt angle from a plane that is perpendicular to a coronal plane, ultrasound scanning mode, and beamsteering angle.
17. The apparatus of claim 12, wherein at least one of said slot-like openings is at least partially skewed relative to a line extending radially from the vertex and passing therethrough.
18. An apparatus for ultrasonically scanning a breast having a skin surface, comprising:
- an ultrasound transducer having a scanning surface; and
- a flexible membrane pressing against the skin surface, the flexible membrane being mounted on a mechanical assembly such that a slot-like opening is formed by a local rising and falling of the flexible membrane relative to the skin surface, the scanning surface of the ultrasound transducer directly contacting the skin surface through said slot-like opening, the flexible membrane not moving laterally as the slot-like opening and ultrasound transducer move laterally across the breast to scan the breast;
- whereby stabilization of the breast and direct transducer-skin contact are concurrently achieved during the scan of the breast.
19. The apparatus of claim 18, wherein said mechanical assembly comprises a roller assembly.
20. The apparatus of claim 18, wherein said flexible membrane compresses the breast in a generally chestward direction during the scan of the breast.
Type: Application
Filed: Aug 30, 2006
Publication Date: Mar 8, 2007
Inventors: Shih-Ping Wang (Los Altos, CA), Jiayu Chen (Palo Alto, CA), Douglas Summers (Palo Alto, CA)
Application Number: 11/513,481
International Classification: A61B 8/00 (20060101);