BREAST ULTRASOUND SCANNING DEVICE

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.

DETAILED DESCRIPTION

FIG. 1illustrates a perspective view of a full-field breast ultrasound (FFBU) scanning apparatus102according to a preferred embodiment, comprising a frame104that may contain an ultrasound processor, a movable support arm106, and a monitor110connected to the support arm106. FFBU scanning apparatus102further comprises a radial scanning template112and an ultrasound transducer114. The radial scanning template112downwardly compresses a breast of a supine patient while rotating around an axis122. The ultrasound transducer114rotates with the radial scanning template112and scans the breast through a slot-like opening therein. For reference purposes herein, the +z direction refers to an outward direction away from the chest wall, the x-axis refers to a left-right direction, and the y-axis refers to a head-to-toe direction. The x-y plane thus corresponds to a coronal plane, the x-z plane corresponds to an axial plane, and the y-z plane corresponds to a sagittal plane.

Also shown inFIG. 1is a rigid two-pronged connector116and a rigid single-armed connector120that mechanically connect the radial scanning template112and the ultrasound transducer114, respectively, to an actuator assembly118for achieving the movement functionalities described herein. It is to be appreciated that the mechanical elements116-120inFIG. 1are drawn by way of conceptual example only. In view of the present disclosure, a person skilled in the art would be readily able to construct the various mechanical linkages, actuators, motors, sensors, etc., required to achieve the described mechanical functionalities without undue experimentation. Accordingly, such mechanical details are mostly omitted from the drawings herein for clarity of description.

Preferably, the support arm106is configured and adapted such that the overall compression/scanning assembly112-120is 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 arm106may comprise potentiometers (not shown) to allow position and orientation sensing for the overall compression/scanning assembly112-120, or other types of position and orientation sensing (e.g., gyroscopic, magnetic, optical, radio frequency (RF)) can be used.

Within frame104may 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.

FIGS. 2-3illustrate more detailed views of the radial scanning template112in accordance with a preferred embodiment. Radial scanning template112has a generally conical shape and defines therein a slot-like opening202and a central opening204. The slot-like opening202is dimensioned to allow the ultrasound transducer114to at least partially pass therethrough to scan the breast. Although shown as a 1D array inFIG. 2, the ultrasound transducer114may more generally be 1D, 1.25D, 1.5D, 2D, or hybridization thereof without departing from the scope of the preferred embodiments. In one preferred embodiment, the FFBU scanning apparatus102is provided with an interchangeable (and/or disposable) set of radial scanning templates112that are differently sized for differently-sized breasts. In one example, three (3) different radial scanning templates having base diameters of 6 inches, 8 inches, and 10 inches are provided. Exemplary diameters for the central opening204range between about 0.25″ to 1.5″. The slot-like opening202may have a width in the range of 0.25″ to 1″ depending on the size of the ultrasound transducer to be inserted therethrough.

In one preferred embodiment, the ultrasound transducer114is supported and actuated independently from the radial scanning template112. In another preferred embodiment, the ultrasound transducer114is integral with, clipped to, or otherwise fused with the radial scanning template112for joint support and/or actuation.

With reference toFIG. 3at view A-A′, the radial scanning template112is shaped similarly to a cone having a vertex302, a base304, and an opening angle θ. In one preferred embodiment, the opening angle θ is greater than 90 degrees and less than 175 degrees. In another preferred embodiment, the opening angle θ is greater than 120 degrees and less than 165 degrees. In yet another preferred embodiment, the opening angle θ is greater than 135 degrees and less than 155 degrees. In general, the opening angle θ should be large enough to provide sufficiently flat chestward compression, while not being so large as to “lose control” of the lateral position of the breast during positioning or rotation.

In one preferred embodiment, the radial scanning template112is 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 template102providing 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 template102comprises 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 template112makes 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 template112. Preferably, a curled lip (not shown) is provided around the base304to prevent skin cuts, similar to the way curled upper lips are provided on many polystyrene and PETE plastic drinking cups.

FIG. 4Aillustrates a side cut-away view of the radial scanning template112as it chestwardly compresses a breast404having a nipple405. The nipple405protrudes through the central opening204. The transducer114scans the breast404through the slot-like opening202.FIG. 4Billustrates a top conceptual view ofFIG. 4A.

In the particular embodiment ofFIGS. 4A and 4B, the slot-like opening202and the ultrasound transducer114both extend along substantially all of a vertex-to-base length of the radial scanning template such that a complete volumetric scan can achieved in a single 360-degree rotation (optionally using beamsteering for facilitating sub-areola imaging). In contrast,FIGS. 5A-5Billustrate a scenario according to another preferred embodiment in which the slot-like opening202extends along substantially all of a vertex-to-base length of the radial scanning template, but in which an ultrasound transducer514extends only along a portion of the slot-like opening. In this preferred embodiment, the ultrasound transducer514is slidably translated along the slot-like opening202during multiple rotations of the radial scanning template112for achieving volumetric completeness.

FIG. 6illustrates a top view of a radial scanning template602according to a preferred embodiment, comprising a central opening604that is contiguous with a slot-like opening606. An ultrasound transducer608can then extend farther inward toward the axis of rotation for better sub-areola imaging.

FIG. 7illustrates a top view of a radial scanning template702according to a preferred embodiment, comprising a central opening704, a slot-like opening706, and a membrane710extending across the slot-like opening706. The ultrasound transducer (not shown) scans the breast through the membrane710.

In one preferred embodiment, the membrane710comprises 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 membrane710comprises 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.

FIG. 8illustrates a top view of a radial scanning template802according to a preferred embodiment. In this preferred embodiment, a membrane810extends across the contiguous combination of a central opening804and a slot-like opening806, whereby an ultrasound transducer (not shown) can then extend farther inward toward the axis of rotation for better sub-areola imaging through the membrane810.

FIG. 9illustrates a top view of a radial scanning template902according to a preferred embodiment, comprising a central opening904and a slot-like opening906, the slot-like opening906being sector-shaped or “pie-shaped”. An ultrasound transducer908is also sector-shaped and comprises, in addition to a full single row of transducer elements912, additional transducer elements914formed in partial rows having greater numbers of elements toward a periphery of the device than toward the center. Where a conventional 1D probe is used in a conventional manner during the scanning rotation, a problem arises in that the scanning is more dense (greater number of voxels per unit volume) near the center while being less dense (lesser number of voxels per unit volume) near the periphery. In such conventional scenario, scanning is unnecessarily slow because of oversampling near the center of the volume, which is a necessary by-product of achieving sufficient sampling at the periphery. In contrast, using the preferred embodiment ofFIG. 9, there is a more uniform scanning distribution. The scanning interval can be faster because oversampling near the center of the volume is avoided.

FIG. 10illustrates a top view of a radial scanning template1002according to a preferred embodiment, comprising a single slot-like opening1004corresponding to a single ultrasound transducer (not shown). The radial scanning template is preferably rotated by 360 degrees plus an overlap angle α during the breast ultrasound scan, the overlap angle α being in a range of 5 to 45 degrees. The coronal sector associated with the overlap angle α (i.e., the pie-shaped sector of the compressed breast subtending the arc between radial lines1022and1024inFIG. 10) is thus imaged twice. The dual volumetric images for the overlap sector can be advantageously used to reduce discontinuity artifacts in the volumetric representation of the breast that might otherwise occur along the radial line1022. In one preferred embodiment, the dual volumetric images are arithmetically averaged for smoothing over the discontinuity. Any of a variety of other mathematical methods for processing the dual volumetric images for reducing discontinuity artifacts are within the scope of the preferred embodiments.

FIG. 11illustrates a conceptual example of a 1D ultrasound transducer firing scheme according to a preferred embodiment. For a particular coronal sector subtending a repeating unit interval β (which may be, for example, 2-10 degrees but exaggerated at 45 degrees for the purposes ofFIG. 11), different combinations of transducer elements are fired as the 1D ultrasound transducer is rotated. More particularly, transducer elements closer to the periphery are fired more often (i.e., at more rotational positions) than transducer elements closer to the vertex. For reasons similar to those presented supra in relation toFIG. 9, a more uniform voxel distribution and faster scanning intervals are facilitated.

FIG. 12illustrates a top view of a radial scanning template1202according to a preferred embodiment, comprising two slot-like openings1204and1206corresponding to two ultrasound transducers (not shown). In one preferred embodiment, the radial scanning template1202is preferably rotated by 180 degrees plus an overlap angle during the breast ultrasound scan, thereby reducing scanning time as compared to the use of a single ultrasound transducer.

In another preferred embodiment, the radial scanning template1202is 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.

FIGS. 13-14illustrate side perspective views of the radial scanning template1202as used in conjunction a first ultrasound transducer1207that scans through slot-like opening1206and a second ultrasound transducer1205that scans through slot-like opening1204, as viewed from the +x direction.FIG. 13illustrates the ultrasound transducers1207and1205in a non-tilted orientation perpendicular to the coronal plane, whileFIG. 14illustrates the ultrasound transducers1207and1205in tilted orientation relative to the perpendicular to the coronal plane, with ultrasound transducer1205having a greater degree of tilt. As illustrated inFIG. 14, ultrasound scans have different elevation profiles (SLICE1205and SLICE1207) into the breast volume, which can then be compounded in various ways to improve image quality.

FIG. 15illustrates a top view of a radial scanning template1502according to a preferred embodiment, comprising three slot-like openings1504,1506, and1508corresponding to three ultrasound transducers (not shown). In one preferred embodiment, the radial scanning template1502is rotated by 120 degrees plus an overlap angle during the breast ultrasound scan, thereby reducing scanning time as compared to the use of fewer ultrasound transducers. In other preferred embodiments, the radial scanning template1502is rotated by the full 360 degrees plus overlap angle and the three (3) resultant scans are compounded in advantageous ways.

FIG. 16Aillustrates a top view of a radial scanning template1602according to a preferred embodiment, comprising four slot-like openings1604,1606,1608, and1610corresponding to four ultrasound transducers (not shown). In one preferred embodiment, the radial scanning template1602is rotated by 90 degrees plus an overlap angle during the breast ultrasound scan, thereby reducing scanning time as compared to the use of fewer ultrasound transducers. In other preferred embodiments, the radial scanning template1602is rotated by the full 360 degrees plus overlap angle and the four (4) resultant scans are compounded in advantageous ways.

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.FIG. 16Billustrates a variant ofFIG. 16Ain which each slot-like opening is skewed relative to a radially-extending line therethrough. In another preferred embodiment, a firing sequence of the ultrasound transducers is adjusted such that two or more of them can be fired simultaneously into the breast volume without mutual interference.

FIG. 17illustrates a top view of a radial scanning template1702according to a preferred embodiment, comprising five slot-like openings1704,1706,1708,1710, and1712corresponding to five ultrasound transducers (not shown). According to the preferred embodiment ofFIG. 17, 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 the example ofFIG. 17, which is for the left breast of the supine patient, the longest ultrasound transducer1706is for scanning the coronal sector nearest the axilla, while the shortest ultrasound transducer1712is for scanning an inferior/medial sector of the breast. Accordingly, it is to be appreciated that the general shape of a radial scan template according to the preferred embodiments is not limited to right cone shapes, but rather can have different vertex locations relative to the base. Likewise, a radial scan template according to the preferred embodiments is not limited to circular, planar basis, but rather can have differently-shaped bases (e.g., oblong, elliptical, cam-like), and/or non-planar bases.

FIG. 18illustrates a conceptual perspective view of an apparatus for ultrasonically scanning a breast according to a preferred embodiment, comprising an ultrasound transducer1804having a scanning surface, and a compressor1802having a compressive surface1806that compresses a skin surface of the breast404, wherein a slot-like opening1809is formed in the compressive surface1806through which the scanning surface of the ultrasound transducer1804directly contacts the skin surface. The compressor1802is configured such that the slot-like opening1809moves laterally over the compressed skin surface in conjunction with the ultrasound transducer1804. Thus, both breast compression and direct skin contact are advantageously provided during the ultrasound scan. In the example ofFIG. 18, the compressive surface1806comprises a flexible membrane and a roller assembly1812causing the membrane to rise and fall relative to the skin surface, but not to move laterally relative to the skin surface, as the ultrasound transducer404is moved laterally across the compressed breast. The ultrasound transducer1804is driven from the side by a mechanical arm1810to accommodate the movement of the membrane thereover. The membrane can comprise any of the materials discussed supra in relation to the membrane710ofFIG. 7.

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.