Patent ID: 12201463

DETAILED DESCRIPTION

The following description relates to various embodiments for digital mammography imaging procedures. Digital mammography imaging procedures may include acquiring 2-dimensional (2D) or 3D digital images of the breast. During imaging using a digital mammography system, the breast of a patient is compressed and an x-ray source may be rotated around the breast within a range of angles in positive and negative directions from a medial position. In some examples, a lesion may first be identified in the patient by a clinician in a diagnostic digital mammography image or by other imaging modalities such as US or MRI. As a result, the clinician may request a biopsy or additional imaging of the lesion.

Some medical procedures, such as breast biopsies, may be carried out with assistance from contrast-enhanced spectral mammography (CESM) performed with a digital mammography system. CESM includes the administration of a contrast agent, such as iodine, to an imaging subject (e.g., patient). The contrast agent may travel to the patient's vasculature, which may assist in biopsy target (e.g., lesion) visualization. Following administration of the contrast agent, dual energy images may be obtained at various points of the biopsy procedure, such as immediately after contrast agent injection and prior to anesthesia delivery, after anesthesia delivery, after biopsy needle insertion, after firing of the biopsy device, after sample collection, and/or after biopsy clip insertion. A dual energy image may be generated from two images, where the two images include a first image acquired with low radiation energy (termed a low energy image, or LE) and a second image acquired with high radiation energy (termed a high energy image, or HE). A digital subtraction process may be used to generate the dual energy (DE) image from the LE image and the HE image, such that background features are removed from the DE image and the contrast-enhanced features (e.g., the lesion) are more clearly visualized.

In some examples, a scout image may be taken to confirm that a lesion which had been previously identified is within a field of view of the digital mammography system and/or within the desired biopsy volume. If the lesion is not identified in the scout image, the clinician may not be able to determine if the lesion is in the field of view but not easily visible, or if the patient needs to be repositioned relative to the digital mammography system. When a CESM is performed, the scout image may be CESM image and a contrast agent may aid in visualizing the lesion. However, the contrast agent may washout of the lesion and/or other x-ray scattering may occur which may hinder identification of the lesion within the image.

Thus, according to the embodiments disclosed herein, a user or computer aided diagnosis (CAD) program may define a ROI (or pixel position) of the biopsy target in any given reference image. A reference image may be taken via an imaging modality capable of visualizing the lesion such as digital mammography, US, MRI, or the like. The registered lesion position may be highlighted in a subsequent image (e.g., comparative image). The reference image and the comparative image may be acquired by common or different imaging modalities. In one example, the scout image may be the comparative image and the registered lesion position may be indicated in a scout image and a clinician may be informed if the registered lesion position is outside a desired region. In some examples, the clinician may be given instructions for repositioning a patient to bring the registered lesion position within the field of view. Additionally or alternatively, the scout image, an initial CESM image or angulated pair of x-ray images may be used as the reference image.

FIG.1is an illustration of a digital mammography system which may be used to acquire images, such as CESM images, during a biopsy or other diagnostic procedure. An image registration method, as shown inFIG.2, may be applied to digital mammography images and/or images from other imaging modalities. The image registration method ofFIG.2is shown pictorially inFIG.3. The registered image may be used to locate a lesion in a scout image of a subsequent imaging procedure following a method shown inFIG.4. The method ofFIG.4is shown schematically inFIG.5. A schematic showing an identification of a lesion position both in and out of a field of view is shown inFIGS.6A-6B, respectively. In another example, a lesion location may be registered in an initial CESM and used to identify the lesion in subsequent CESM images if the lesion location becomes obscured due to washout or scatter. A method for locating the lesion from an initial CESM image registration is shown inFIG.7. The method ofFIG.7is shown schematically inFIG.8. In some examples, CESM images may be acquired as viewed from different angular positions (e.g., angular view pairs) resulting in calculated 3D coordinates. A lesion position may be registered in angular view pairs and used for locating the lesion in subsequent stereotactic images as shown in the method ofFIG.9. The method ofFIG.9is shown schematically inFIG.10.

Referring toFIG.1, a digital mammography system100including an x-ray system10for performing a mammography procedure is shown, according to an embodiment of the disclosure. The x-ray system10may be a used to acquire a scout image and subsequent images for a CESM procedure and/or biopsy procedure.

The x-ray system10includes a support structure42, to which a radiation source16, a radiation detector18, and a collimator20are attached. The radiation source16is housed within a gantry15that is movably coupled to the support structure42. In particular, the gantry15may be mounted to the support structure42such that the gantry15including the radiation source16can rotate around an axis58in relation to the radiation detector18. An angular range of rotation of the gantry15housing the radiation source16indicates a rotation up to a desired degree in either direction about the axis58. For example, the angular range of rotation of the radiation source16may be −θ to +θ, where θ may be such that the angular range is a limited angle range, less than 360 degrees. An exemplary x-ray system may have an angular range of ±11 degrees, which may allow rotation of the gantry (that is rotation of the radiation source) from −11 degrees to +11 degrees about an axis of rotation of the gantry. The angular range may vary depending on the manufacturing specifications. The angular range for digital mammography systems may be approximately ±11 degrees to ±60 degrees, depending on the manufacturing specifications.

The radiation source16is directed toward a volume or object to be imaged and is configured to emit radiation rays at desired times to acquire one or more images. The radiation detector18is configured to receive the radiation rays via a surface24. The detector18may be any one of a variety of different detectors, such as an x-ray detector, digital radiography detector, or flat panel detector. The collimator20is disposed adjacent to the radiation source16and is configured to adjust an irradiated zone of a subject.

In some embodiments, the system10may further include a patient shield36mounted to the radiation source16via face shield rails38such that a patient's body part (e.g., head) is not directly under the radiation. The system10may further include a compression paddle40, which may be movable upward and downward in relation to the support structure along a vertical axis60. Thus, the compression paddle40may be adjusted to be positioned closer to the radiation detector18by moving the compression paddle40downward toward the detector18, and a distance between the detector18and the compression paddle40may be increased by moving the compression paddle upward along the vertical axis60away from the detector. The movement of the compression paddle40may be adjusted by a user via compression paddle actuator (not shown) included in the x-ray system10. The compression paddle40may hold a body part, such as a breast, in place against the surface24of the radiation detector18. The compression paddle40may compress the body part and hold the body part still in place while optionally providing apertures to allow for insertion of a biopsy needle, such as a core needle or a vacuum assisted core needle. In this way, compression paddle40may be utilized to compress the body part to minimize the thickness traversed by the x-rays and to help reduce movement of the body part due to the patient moving. The x-ray system10may also include an object support (not shown) on which the body part may be positioned.

The digital mammography system100may further include a workstation43comprising a controller44including at least one processor and a memory. The controller44may be communicatively coupled to one or more components of the x-ray system10including one or more of the radiation source16, radiation detector18, the compression paddle40, and a biopsy device. In an embodiment, the communication between the controller and the x-ray system10may be via a wireless communication system. In other embodiments, the controller44may be in electrical communication with the one or more components of the x-ray system via a cable47. Further, in an exemplary embodiment, as shown inFIG.1, the controller44is integrated into the workstation43. In other embodiments, the controller44may be integrated into one or more of the various components of the system10disclosed above. Further, the controller44may include processing circuitry that executes stored program logic and may be any one of different computers, processors, controllers, or combination thereof that are available for and compatible with the various types of equipment and devices used in the x-ray system10.

The workstation43may include a radiation shield48that protects an operator of the system10from the radiation rays emitted by the radiation source16. The workstation43may further include a display50, a keyboard52, mouse54, and/or other appropriate user input devices that facilitate control of the system10via a user interface56.

The controller44may adjust the operation and function of the x-ray system10. As an example, the controller44may provide timing control, as to when the x-ray source16emits x-rays, and may further adjust how the detector18reads and conveys information or signals after the x-rays hit the detector18, and how the x-ray source16and the detector18move relative to one another and relative to the body part being imaged. The controller44may also control how information, including images42and data acquired during the operation, is processed, displayed, stored, and manipulated. Various processing steps as described herein with respect toFIGS.2,4,7, and9performed by the controller44, may be provided by a set of instructions stored in non-transitory memory of the controller44.

Further, as stated above, the radiation detector18receives the radiation rays22emitted by the radiation source16. In particular, during imaging with the x-ray system, a projection image of the imaging body part may be obtained at the detector18. In some embodiments, data, such as projection image data, received by the radiation detector18may be electrically and/or wirelessly communicated to the controller44from the radiation detector18. The controller44may then reconstruct one or more scan images based on the projection image data, by implementing a reconstruction algorithm, for example. The reconstructed image may be displayed to the user on the user interface50via a display screen56.

The radiation source16, along with the radiation detector18, forms part of the x-ray system10which provides x-ray imagery for the purpose of one or more of screening for abnormalities, diagnosis, dynamic imaging, and image-guided biopsy. For example, the x-ray system10may be operated in a mammography mode for screening for abnormalities. During mammography, a patient's breast is positioned and compressed between the detector18and the compression paddle40. Thus, a volume of the x-ray system10between the compression paddle40and the detector18is an imaging volume. The radiation source16then emits radiation rays on to the compressed breast, and a projection image of the breast is formed on the detector18. The projection image may then be reconstructed by the controller44, and displayed on the interface50. During mammography, the gantry15may be adjusted at different angles to obtain images at different orientations, such as a cranio-caudal (CC) image and a medio-lateral oblique (MLO) image. In one example, the gantry15may be rotated about the axis58while the compression paddle40and the detector18remain stationary. In other examples, the gantry15, the compression paddle40, and the detector18may be rotated as a single unit about the axis58.

Further, the x-ray system10may be operated in a tomosynthesis mode for performing digital breast tomosynthesis (DBT). During tomosynthesis, the x-ray system10may be operated to direct low-dose radiation towards the imaging volume (between the compression paddle40and the detector18) at various angles over the angular range of the x-ray system10. Specifically, during tomosynthesis, similar to mammography, the breast is compressed between the compression paddle40and the detector18. The radiation source16is then rotated from −θ to +θ, and a plurality of projection images of the compressed breast is obtained at regular angular intervals over the angular range. For example, if the angular range of the x-ray system is ±11 degrees, 22 projection images may be captured by the detector during an angular sweep of the gantry at approximately one every one degree, generating a set of angulated x-ray images. The plurality of projection images are then processed by the controller44to generate a plurality of DBT image slices. The processing may include applying one or more reconstruction algorithms to reconstruct three dimensional image of the breast. Furthermore, the x-ray system may be configured to perform a DBT-guided biopsy procedure. Accordingly, in some exemplary embodiments, the system10may further include a biopsy device comprising a biopsy needle for extracting a tissue sample for further analysis.

In some examples, digital mammography system100may be configured to perform contrast imaging where contrast agents, such as iodine, can be injected into the patient and travel to the ROI within the breast (e.g., a lesion). The contrast agents are taken up in the blood vessels surrounding a cancerous lesion in the ROI, thereby providing a contrasting image for a period of time with respect to the surrounding tissue, enhancing the ability to locate the lesion.

The use of a contrast agent can be coupled with images of the ROI taken using dual-energy imaging processes and technology. In dual-energy imaging, low-energy (LE) and high-energy (HE) images are taken of the ROI. In particular, contrast enhanced spectral mammography (CESM) (2D) and contrast enhanced digital breast tomosynthesis (CE-DBT) (3D) imaging modalities are performed with dual-energy technology. For each view (single view in CESM, multiple views for CE-DBT), a pair of images is acquired: a low-energy (LE) image and a high-energy (HE) image. In CE-DBT, non-paired HE and LE images may be acquired for each view and an HE volume, LE volume, and recombined CE volumes may be reconstructed for the ROI. For example, the HE and LE views may be interleaved during the CE-DBT scan (alternatively HE, LE, HE, LE, HE, LE, etc.) with a switch from HE to LE then to HE again etc., for each angulated position of the x-ray tube. The LE and HE images are usually obtained at mean energies above and below the k-edge of the contrast agent. At x-ray energies just above the k-edge of the contrast agent, the absorption of x-rays is increased resulting in an increase of contrast from the iodine contrast agent in the HE image.

In dual-energy 3D or stereotactic procedures, LE and HE image acquisitions are performed, with at least two different positions of the x-ray source with respect to the detector. The images are then recombined to display material-specific information with regard to the internal structure of the tissue being imaged. In the case of 3D CESM, for example, after the injection of contrast medium, dual-energy images are acquired at two or more positions of the x-ray tube with respect to the detector. For each of these tube angulations, the low and high-energy images are recombined to produce an image of the contrast medium surface concentration at each pixel to provide an iodine-equivalent or dual-energy (DE) image(s) (for a single view in CESM, and for multiple views for CE-DBT), which in CE-DBT, are used to reconstruct a 3D volume. Image recombination may be performed based on simulations of the x-ray image chain, via calibrations on a reference phantom, or any other suitable 3D-reconstruction process. Additionally, in the continuous mode of acquisition where the x-ray tube moves continuously with interleaved HE and LE images being taken, the LE images are used to reconstruct a LE 3D volume, and the HE images are used to reconstruct a HE 3D volume, with both volumes being recombined in a suitable manner to provide an iodine 3D volume. In some examples, 3D-reconstruction and HE/LE recombination may be performed in a single step.

Before a CESM or a CE-DBT procedure, a scout image may be acquired to confirm that a previously identified lesion is within a desired region of the acquired mage. If a user (e.g., clinician) does not identify the lesion, it may be due to the lesion being outside of the desired region, or the lesion is within the desired region, but obscured for other reasons. For this reason, identification of a position of the lesion in a previous reference image may be used to display a graphical representation of the position of the lesion in the scout image. The reference image may be a previously acquired diagnostic mammogram or image obtained via a different imaging modality such as US or MRI. Additionally, a position of the lesion may become obscured during an imaging procedure, such as a biopsy. In such an example, an earlier image of the imaging procedure may be used as the reference image. In one example, the graphical representation may include indicating that the position of the legion is outside an image frame of the scout image. In this way, the user may confidently confirm the position of the lesion before and/or during a follow-up procedure such as a biopsy.

FIG.2is an image registration method200that may be applied to images acquired by a digital mammography system (e.g. digital mammography system100ofFIG.1) to compare or integrate data obtained within different images from an image set. In some examples, method200may compare images obtained with different imaging modalities. As one example, image registration may be used as a preliminary step in other image processing applications, such as to track a lesion in a scout image (seeFIG.4). Method200may be executed using computer readable executable instructions stored in the non-transitory memory of a computing device of a digital mammography system (e.g., digital mammography system100ofFIG.1) or a controller communicatively coupled to the digital mammography system (e.g., controller44ofFIG.1). In some embodiments, method200may be executed by another computing device without departing from the scope of this disclosure (e.g., an edge device, a picture archiving and communication system (PACS)).

At202, method200includes selecting a reference image and a comparative image from an image set acquired by the digital mammography system and/or other imaging modalities. In some examples, more than one reference image may be selected. The reference image herein may be defined as the image to which the comparative image (or images) is aligned during image registration. In some examples, the reference image and comparative image may be taken during the same imaging procedure. The reference image may be a low energy image and the comparative image may be a high energy image, in some examples. In other examples (such as when the image registration method is performed to track a CESM biopsy target according to the method ofFIG.7), the reference image may be a low energy image acquired during a point in time when the biopsy target was still visible in contrast-enhanced images and the comparative image may be a low energy image taken at a time subsequent to the reference image, at a point in time when the biopsy target was no longer visible in contrast-enhanced images, and thus motivating the user of the digital mammography system to switch to non-contrast imaging. In still other examples, the reference image may be an image obtained via digital mammography and/or other imaging modalities during a previous imaging procedure and stored in the non-transitory memory of the computing device. The reference image and the comparative image may be images of the same anatomical features/scan plane of the same patient. Further, the reference image and comparative images may be acquired by common or different imaging modalities.

Optionally, at203, method200may include pre-processing the comparative image. In one example, the comparative image may be acquired as part of a biopsy procedure and may therefore include an artifact from a compression paddle used as part of the biopsy procedure (see, for example, artifact809ofFIG.8below). Pre-processing may include defining a relevant region of the comparative image which may be free of artifacts (e.g., between paddle artifacts). As a result of pre-processing, the image registration may ignore the artifacts which may be present in the comparative image and not the reference image.

At204, method200includes performing image registration on the selected images. During image registration, the comparative image may be aligned to the reference image via a spatial domain method. In one example, such as when the reference image and comparative image are of the same imaging modality, the spatial domain method may define features in terms of pixel intensities. In another example, such as when the reference image and comparative image are of different imaging modalities, the spatial domain method may define features in terms of geometrical location and/or morphologic characteristics. The spatial domain method may include selecting control points within the reference image and the comparative image at206. The control points may be individual pixels or groups of neighboring pixels. The control points may be selected randomly in one example. In another example, the control points may be selected based on a predefined grid or other pattern. In a still further example, the control points may be selected based on which pixels/anatomical regions of the comparative image are likely to move from image to image, such as pixels at edges of anatomical structures. The control points may be at the same location in each of the reference image and the comparative image.

At208, a local shift computation may be performed between the control points of the two images. The local shift computation may indicate, for each control point of the comparative image, the magnitude and direction of shift of that control point relative to the reference image. For example, the local shift computation may generate a motion vector that comprises the vector difference between the position x,y (for rows and columns) of the same clinical/anatomical feature (e.g., a micro calcification or a lesion) in the two images: dx=x1−x2, dy=y1−y2.

At210, pixel-wise interpolation may be performed based on the local shift computation. The interpolation may include a first interpolation that is performed to pass from the motion vectors at each control point to a motion vector field with motion vectors at every image pixel (e.g., the pixel wise interpolation309inFIG.3). The first interpolation may include B-spline interpolation or another suitable interpolation. Thus, the first interpolation may include a B-spline interpolation to generate a motion vector field, as indicated at212, where the motion vector field includes a respective motion vector at every pixel based on the motion vectors at the control points. A second interpolation may be performed where, for every pixel p (xp, yp) in the comparative image (e.g., the image that is being registered), the vector field value at pixel p (dx,dy) is used to retrieve the image pixel value in position (xp+dx, yp+dy) in the same image (because that is where the pixel is supposed to be, according to the reference image). Since dx and dy are not integer values, interpolation is performed on the surrounding pixels using a linear or cubic function, for example, which may create a registered image as explained below.

FIG.3shows an example image registration process300according to an embodiment of the disclosure. The image registration process300shown inFIG.3may be carried out according to the method ofFIG.2. The image registration process300includes the registration of two images, shown at302. The two images include a reference image301and a comparative image303. The reference image301may be acquired at an earlier point in time or with a different imaging modality than the comparative image303. As explained above, the reference image may be a reference LE image acquired during peak contrast enhancement (or least when a biopsy target is sufficiently visible) while the comparative image may be an LE image acquired at any point after the reference LE image. In another example, the reference image301may be a previously obtained image acquired via digital mammography, ultrasound, MRI, or similar imaging modalities.

At304, the two images are registered by selecting control points, computing a local shift at each control point, and performing a pixel-wise interpolation. Example control points305and example local shift vectors307are shown on comparative image303. As appreciated byFIG.3, the local shift computation may include determination of a vector quantifying direction and magnitude of motion/shift for each control point of the comparative image relative to the corresponding control point of the reference image. The pixels of the comparative image are then interpolated on a pixel-wise basis using an interpolation grid309. Each pixel may be interpolated based on the pixel values of neighboring pixels and the motion vectors as described above. The output of the image registration process300is a registered image306, which may in some examples be the comparative image303with adjustments made to some pixels in order to register (e.g., align) features of the comparative image303with the reference image301. However, when tracking a biopsy target with a target marker, the output of the image registration process may include an indication of where, in the comparative image, the lesion target is located, based on determining movement of pixels/tissue in the comparative image relative to the reference image. In one example, the output of the image registration process may include an indication that the lesion target is out of the field of view. Further, in some examples, the output of the image registration process may include instructions to the user for re-positioning in order to position the lesion within the field of view.

Turning now toFIG.4, a method400is shown for using an image registration process (such a method200ofFIG.2) to determine a position of a lesion relative to a desired region of a scout image acquired by a digital mammography system. Method400may be executed using computer readable executable instructions stored in the non-transitory memory of a computing device of a digital mammography system (e.g., digital mammography system100ofFIG.1) or a controller communicatively coupled to the digital mammography system (e.g., controller44ofFIG.1). Outputs of method400may be visualized on a display connected in communication with the computing device. In some embodiments, method400may be executed by another computing device without departing from the scope of this disclosure (e.g., an edge device, a picture archiving and communication system (PACS)).

At402, method400includes acquiring a scout image. The scout image may be obtained with the x-ray source in a single/fixed position (e.g., a medial position, obtained with the x-ray tube positioned at zero degrees from a midline axis perpendicular to the top surface of the detector). The scout image may be a low dose, short exposure image. In some examples, a brightness of the scout image may be assessed to determine the x-ray technique (e.g., x-ray source current and voltage) for subsequent images.

At404, method400includes determining if a lesion is identified in the scout image. Identifying the lesion may include both confirming the lesion is seen in the scout image and that it is the same lesion that was identified in a prior diagnostic image. The lesion may be identified by either a user (e.g., technician) or CAD instructions also included in the controller. If the lesion is identified, method400proceeds to406and includes proceeding with an imaging procedure. The imaging procedure may be a biopsy performed with CESM or CE-DBT. If the lesion is not identified in the scout image at404, method400proceeds to408. The lesion may be considered not identified if the user does not see the lesion in the scout image or if the user sees a feature, but is unsure if it is the previously identified lesion.

At408, method400includes selecting a reference image and identifying a ROI. In some examples, one or more reference images may be selected. The reference image may be an image acquired during a separate imaging procedure performed previously where the lesion has been identified by either a user or CAD. The reference image or images may be common or different imaging modality than the scout image. In one example the reference image may be a previous digital mammography image. In other examples, the reference image may be pervious ultrasound or MRI image. In an example where the user sees a feature, but is unsure if it is a lesion, the scout image may be the reference image. A first ROI indicating a location of the lesion on the reference image may be placed on the reference image by the user or by a CAD to identify the first ROI.

At410, method400includes registering the reference image selected at408to a comparative image. As one example, the comparative image may be the scout image acquired at402. In an example where the scout image is the reference image, an image acquired previously where the lesion was identified may be a comparative image to which the scout reference image is registered. Image registration may include mapping of features of the reference image onto a comparative image (e.g., the scout image) as described above with respect toFIGS.2-3. Features may be intensity and/or geometry based.

At412, method400includes reporting a position of the lesion from the reference image to the comparative image. The position may be reported by a second ROI generated on the comparative image. In one example, a position of the lesion may be shown on the scout image as a result of registering the scout image to the reference image at410. In an example where the scout image is the reference image, the second ROI may be generated on the previous image. In this way, the second ROI may allow the user to confirm if the lesion identified in the scout image is the same as the lesion identified in the previous image.

If second ROI generated at412indicates that the lesion is not positioned in a desired region, at414, method400may include providing an indication that the lesion is out of the desired region. The indication may be a first notification which is written or symbolic (e.g., arrows or brackets) instructions. In some examples, the first indication may be an audio notification. In some examples, method400may also include, at416, providing repositioning instructions (e.g., move patient to the left) to help position the lesion within the scout image for a subsequent image. Further, the second ROI may be used for comparing a position of the lesion to a biopsy volume, including repositioning instructions which may help position the lesion within the biopsy volume for a biopsy procedure. The desired biopsy volume may be indicated on the scout image by a second notification including a square indicating the biopsy volume generated at a display of the computing device (e.g., workstation). First or second notifications may include written or symbolic repositioning instructions. Repositioning instructions may be displayed written text instructions on a screen of a display device of the digital mammography system (e.g. workstation43ofFIG.1). Additionally or alternatively, repositioning instructions may be displayed symbolically as arrows on the screen of the display device indicating a direction to move the patient. In some embodiments, repositioning instructions may be given by an audio notification. An embodiment illustrating indication of the first ROI and the second ROI is shown inFIG.5.

At413, method400includes determining if the patient was repositioned. The patient may be repositioned following step412if the identified position of the lesion is outside a desired biopsy volume or outside a desired region of the scout image. If the patient was repositioned, method400returns to402and the scout image is re-acquired. If the patient was not repositioned, method400proceeds to406. The patient may not be repositioned after step412if after the lesion position is identified, it can be seen that the patient was positioned properly, but the lesion was not visible due to other reasons, such as obscuring of the lesion by a biopsy needle or contrast agent washout.

In this way, the user may know a position of the lesion with greater certainty and, if required, may reposition the patient to successfully view the lesion in a subsequent scout image. The procedure may therefore be shorter than repositioning of the patient by the user via trial-by-error, e.g., without guidance. Further, the method may allow distinction between whether the lesion is not visible due to position or if the position is correct but the lesion is not visible due to other reasons (e.g., scatter or washout). Additionally, a number of scout image retakes may be reduced thereby reducing the patient's x-ray dosage.

Method400may be shown schematically via diagram500ofFIG.5. Diagram500may include reference images502and comparative image510. In one example, as shown inFIG.5, comparative image510may include a scout image511acquired at a start of an imaging procedure. A lesion may or may not be in the field of view of scout image511. Reference images502may include a first view of the lesion504, and a second alternate view of the lesion506. Reference images502may be taken during a separate imaging procedure performed before acquiring scout image511. In some examples, reference images502may be acquired using a different imaging modality than the imaging modality by which scout image511was acquired. Each reference image502may include a first ROI503indicating a position of the lesion within the image. The first ROI503may be placed by a user or by a CAD program.

Comparative image510and reference images502may be inputs of registration process512. Registration process512may include overlaying features of comparative image510and reference images502as described above with respect toFIGS.2and3. One or all of reference images502may be inputs of registration process512.

Outputs of registration process512may include scout image511annotated with a second ROI513. The second ROI513position may correspond to a position of the lesion in the comparative image. In some examples a lesion evaluation514may also be output by registration process512. Lesion evaluation514may include prompts displayed to the user that the lesion is in or out of a desired region for the imaging process. In some examples, where the imaging process may be a biopsy, lesion evaluation514may include indicating by a prompt displayed to the user that lesion is in or out of a volume which may be accessed for biopsy. Further, registration process512may output repositioning instructions516. Repositioning instructions516may be output as a prompt displayed to the user if the lesion is outside of an image frame. For example, repositioning instructions516may instruct a user to move a breast of a patient in a direction (e.g., left, right, up, or down) relative to an x-ray tube and detector.

Turning now toFIG.6A-6B, annotated images600and650are shown. Annotated images600and650may be similar to annotated images output as a result of a registration process as described above with respect toFIG.5showing the relative position of a lesion. Annotated image600shown inFIG.6Amay include a scout image602wherein a lesion is within the image frame of the scout image (e.g., within a desired region). Scout image602may include an ROI604generated by the registration process which surrounds the lesion in scout image602.

Annotated image650shown inFIG.6Bmay include scout image652where a lesion is outside the image frame the scout image (e.g., outside of the desired region). As one example, annotated image650may include an arrow654pointing in a direction corresponding to where the lesion would be outside the frame of scout image652. Additionally or alternatively, annotated image650may include bracket656which may indicate a one dimensional region (e.g., a length along an edge of scout image652) in which the lesion may be located outside the frame of scout image652. In other examples, annotated image650may additionally or alternatively include written (e.g., text), audio, or other symbolic instructions indicating where the lesion may be positioned relative scout image652.

A scout image may be taken before an imaging procedure such as a CESM procedure. In one example, the CESM procedure may be performed as part of a biopsy procedure to increase a contrast of the lesion which is being biopsied. As described inFIG.7below, a registration process may be used to help identify a position of a lesion if visibility is lost during a CESM procedure due to x-ray scattering or contrast media being washed out of the lesion.

Turning now toFIG.7, a method700is shown for using an image registration process (such a method200ofFIG.2) to determine a position of a lesion within an image frame during a CESM procedure. Method700may be executed using computer readable executable instructions stored in the non-transitory memory of a computing device of a digital mammography system (e.g., digital mammography system100ofFIG.1) or a controller communicatively coupled to the digital mammography system (e.g., controller44ofFIG.1). In some embodiments, method700may be executed by another computing device without departing from the scope of this disclosure (e.g., an edge device, a picture archiving and communication system (PACS)). Outputs of method700may be visualized on a display connected in communication with the computing device.

At702, method700includes acquiring a CESM image. A CESM image may be acquired after injection of a contrast medium such as iodine. Further, acquiring a CESM image may include acquiring both a high energy and low energy image and subtracting the two images to obtain a dual energy image as described above with respect toFIG.1. The CESM image may be a scout image or an image acquired at any time during the CESM procedure.

At704, method700includes determining if the lesion is visible in the CESM image. A CESM image with a visible lesion may be an image wherein the contrast medium is localized within the lesion and the lesion location may be confidently identified by the user or a CAD program. If the lesion is visible, method700continues to716and the CESM procedure proceeds. If the lesion is not visible in the CESM image, method700proceeds to706and includes selecting a reference image and a first ROI. Selecting the reference image and first ROI may be performed by a user. A lesion may not be visible in a CESM image if the contrast media has washed out of the lesion or if a biopsy needle is inserted and causes x-ray scattering. Additionally or alternatively, the lesion may not be visible in the CESM image because the patient has moved and the lesion is outside of a field of view of the CESM image. The reference image may be a previous CESM image taken at a beginning of the CESM procedure. The previous CESM image may be an HE, LE, or combined image as described above with respect toFIG.1. At a beginning of the CESM procedure there may be less of a chance of washout or scattering obscuring the position of the lesion. Additionally or alternatively, the reference image may be a CESM image taken during a previous procedure, or an image taken using a different imaging modality such as MRI. The ROI may be designated by the user or automatically designated by CAD instructions stored on a controller which may be the same or different than the controller on which method700may be stored. In some examples, more the one reference image may be selected. For example, a CESM image from an earlier procedure and a non-CESM image from a previous exam may both be selected as reference images.

At708, method700includes registering the reference image and the acquired CESM image. The registration process may map features of the selected reference image and ROI of step706onto features of the acquired CESM image. Registering the image may be include following steps of method200FIG.2and diagramed inFIG.3above.

As a result of step708, method700includes indicating the position of the lesion with respect to the CESM image at710. In one example, at710, method700may include generating an annotated image including a second ROI surrounding the lesion. If the second ROI indicates that the lesion is no longer in a desired region of the CESM image at710, method700may include at712indicating that the lesion is out of the desired region. The indication may be given as a first written text or symbolic notification appearing on the image. In an example where the CESM procedure is a biopsy procedure, method700may indicate with a second notification if the lesion is within a biopsy volume. In one example, the notification may include comparing the biopsy volume with the second ROI. Further, at714, method700may include giving instructions to the user regarding a direction in which to reposition the patient so that the lesion may be in the desired region of the CESM image. As one example, directions may be indicated symbolically as described above with respect toFIG.6B. Additionally or alternatively, directions may be given by written and/or audio prompts.

At715, method700includes determining if the patient was repositioned. As described above, the patient may be repositioned based on the indicated position of the lesion at710to place the lesion within the desired region of the CESM image and/or within a biopsy volume. If the patient was repositioned, method700returns to702. If the patient was not repositioned, method700proceeds to716. The patient may not be repositioned if the lesion position is indicated at710and shows that the lesion is still in the desired region of the image and/or within the biopsy volume.

In this way, if the lesion position is not readily seen on the CESM image, a user may determine whether a position of the patient has changed, or if the lesion has lost contrast media, or both. When the user correctly determines the lesion position, a number of image retakes and thereby patient radiation exposure may be reduced. The CESM procedure may continue at716and a user may be able to identify a position of the lesion. Method700returns and may be repeated during a CESM procedure.

Method700may be shown schematically via diagram800ofFIG.8. Diagram800may include reference images802and a comparison image808. Reference images802may be CESM images where the lesion is visible. Reference images802may be HE, LE, or DE images or any combination thereof. Reference images may include an ROI803which may be placed by a user or by CAD program. Reference images802may include a first view804and a second806. First view804and second view806may be different views of the same lesion wherein the lesion is readily identified. As described above with respect to method700, reference images802may be collected during a beginning of a CESM procedure where interference due to washout of contrast media or scattering may be less likely.

Comparison image808may be an image810wherein the lesion is no longer identifiable. The lesion may no longer be identifiable due to x-ray scatter, washout of the CESM contrast media, or due to movement of the lesion outside of a field of view of the procedure. In one example, image810may be acquired at a different angle than first view804or second view806. In some examples, image810may be a scout image. In other examples image810may be collected over the course of a CESM procedure which may be a biopsy procedure. Image810may also include artifacts809, which may be present due to use of a compression paddle when the CESM procedure is a biopsy procedure.

Reference images802and comparison image808may be mapped onto each other via registration812. Registration812may be similar to the registration process described above with respect toFIGS.2and3. For example, a pre-registration process may define a region between artifacts809to register to the reference image.

Registration812may output image810with an annotation of ROI815. ROI position815may correspond to a location of the lesion on comparison image808. In some examples registration812may also output lesion evaluation816. Lesion evaluation816may include communicating to the user if the lesion is in or out of the field of view. Further, lesion evaluation816may include communicating to the user if the lesion is in or out of a volume that may be accessed by a biopsy needle (e.g., biopsy volume). Communication of lesion evaluation816may include annotating comparison image808to indicate at which edge of comparison image810the lesion may be located, as described above with respect toFIG.6B. The communication may also include other written or audio prompts to the user by the controller. In some examples registration812may also output repositioning instructions818. Repositioning instructions818may be written or audio prompts to the user by the controller for moving a patient or components of a digital mammography system to move the lesion into the field of view.

As described above with respect toFIG.1, a digital mammography system, such as digital mammography system100, may be operated in tomosynthesis mode in which x-ray scans may be taken at different angles to assemble a stereotactic image which may be used to calculate positions in 3D. The different angled acquisitions (angulations) may be collected in pairs (e.g., +15° and −15°). In some examples, a position of a lesion may be easily identified in a first pair of angulations, but may become no longer visible during a subsequent acquisition. Additionally or alternatively, the digital mammography system may be operated in CE-DBT mode and a plurality of angulated images may be collected to form a 3D image, as described above with respect toFIG.1. An image registration process as described below with respect toFIG.9may be able to locate the position of the lesion in any 3D position.

Turning now toFIG.9, a method900is shown for using an image registration process (such a method200ofFIG.2) to determine a position of a lesion relative to a field of view of an image during a biopsy procedure. Method900may be executed using computer readable executable instructions stored in the non-transitory memory of a computing device of a digital mammography system (e.g., digital mammography system100ofFIG.1) or a controller communicatively coupled to the digital mammography system (e.g., controller44ofFIG.1). In some embodiments, method900may be executed by another computing device without departing from the scope of this disclosure (e.g., an edge device, a picture archiving and communication system (PACS)). Outputs of method900may be visualized on a display connected in communication with the computing device.

At902, method900includes collecting angulated pairs of x-ray images. The angulated x-ray image pairs may be collected at displacement angles of the x-rays (e.g., +15° and −15°). In some examples, the angulated pairs of images may be CESM images whereby a LE, and HE images may be collected. In an alternate example, a plurality of angulated images may be collected as part of a CE-DBT procedure.

At904, method900includes determining if the lesion is visible in the angulated x-ray images. In some examples where a contrast media is used, the lesion visibility may depend on whether the contrast media has washed out of lesion area. In other examples, the angulated pair of images may be taken with a biopsy needle inserted into the breast tissue, whereby the biopsy needle may obscure the position of the lesion. If the lesion is visible, method900proceeds to912and includes continuing the biopsy procedure.

If the lesion is not visible, method900includes, at906, selecting a pair of angulated images as reference images and first ROIs. The first ROIs may be added by a user or CAD program to identify a location of the lesion. In an example where CESM images are collected, the reference images may be collected at a beginning of the procedure, before the contrast media is washed out from the lesion area. Further, the pair of angulated images selected as reference images may be HE, LE, or DE images. In some examples, a scout image taken at the beginning of the procedure may also be selected as a reference image. In other examples, the pair of angulated images may be taken during a previous imaging session. Additionally or alternatively, reference images may be selected from a CE-DBT procedure and may include a plurality of angulated images. Further, more than one set of reference images may be chosen.

At908, method900includes registering the collected angulated pair where the lesion is not visible to the reference image as selected at906. Image registration may be performed following the method described above with respect toFIGS.2and3.

At910, method900includes annotating the location of the lesion in the 2D stereotactic image on which registration was performed. In an example where CESM images are collected, the location may be annotated in HE, LE or DE images. The annotations may include indicating a position of the lesion on the stereotactic 2D images, from which the 3D position of the lesion may be calculated and of a second set of ROIs may be generated around the lesion. In an example where the reference images are of a DBT procedure, the second set of ROIs may be generated on a 3D image. Further, whether or not the lesion is within a target biopsy volume may be addressed by a notification shown on a display of the computing unit. Additionally or alternatively, annotations may indicate if the lesion is not within a field of view of the image and may give indications of a direction of the lesion relative to the image.

At911, method900determines if the patient was repositioned. The patient may be repositioned to place the lesion within the target biopsy volume and/or the field of view of the stereotactic images. If the patient was repositioned, method900returns to902. If the patient was not repositioned, method900proceeds to912. The patient may not be repositioned if at910the annotated image shows the lesion is in the frame of the stereotactic images and within the target biopsy region. At912, a biopsy procedure is performed. The biopsy procedure may continue to collect images of the lesion at different angulated image pairs. Method900returns.

Method900may be shown schematically by diagram1000ofFIG.10. Diagram1000includes reference images1002and comparison images1008. Reference images1002may include a first reference angulated image1004and a second reference angulated image1006. First reference angulated image1004and second reference angulated image1006may together comprise an angulated image pair1005. Angulated image pair1005may be taken at equal and opposite rotations of an x-ray system, such as x-ray system10ofFIG.1. First reference angulated image1004and second reference angulated image1006may each include an ROI1003identifying a location of the lesion. ROI1003may be placed by a user or by a CAD program.

Comparison images1008may include a first comparison angulated image1010and a second comparison angulated image1012which together may comprise an angulated image pair1007. Angulated image pair1007may be collected at the same or different pair of angles as angulated image pair1005. The position of the lesion may no longer be visible in angulated image pair1007. As shown inFIG.10, the lesion may no longer visible due to obstruction by a biopsy needle1009. In other examples the lesion may no longer be visible due to a contrast media becoming washed out or due to scatter or the x-rays.

Reference images1002and comparison images1008may be inputs to registration process1014. Registration process1014may map features of reference images1002onto comparison images1008according to the method described above with respect toFIGS.2and3.

Registration process1014may output angulated image pair1007including ROI1003annotating the location of the lesion in first comparison angulated image1010and in second comparison angulated image1012. Further, registration process1014may output a location of the lesion1015on comparison images1008. The location of the lesion in 3D1016may include the location of the lesion across any angulated image taken during the procedure.

The technical effect of methods400ofFIG.4,700ofFIG.7, and900ofFIG.9is to allow a user to identify, with increased certainty and efficiency, a position of a lesion relative to a digital mammography image using a previous identified position in a different image. The methods may allow the user to differentiate between a lesion present in an image but not visible and a lesion not present in an image due to patient positioning. A reference image used for methods described above may be an earlier digital mammography image taken during a current or previous imaging procedure or an image taken using a different imaging modality. In this way, a user may more readily identify a lesion within an image or be instructed to move a patient in a direction to place the lesion within a frame of the image. A time and radiation dose required for the procedure may be minimized due to increased speed and accuracy in identifying the position of the lesion.

The disclosure also provides support for a method for imaging, comprising: acquiring a comparative image of a patient, aligning the comparative image with a reference image, at a processor, by registering the comparative image to the reference image, the reference image including an ROI corresponding to a lesion, mapping the ROI of the reference image onto the comparative image, and displaying the comparative image at a display screen with instructions indicating a relative position of the ROI in response to the ROI being outside of a desired region of the comparative image. In a first example of the method, the comparative image is a scout image acquired with an x-ray detector. In a second example of the method, optionally including the first example, the reference image is one or more of an x-ray image, ultrasound (US) image, or magnetic resonance imaging (MRI) image, the ROI of the reference image being outside of the desired region of the comparative image. In a third example of the method, optionally including one or both of the first and second examples, the reference image is taken prior to the comparative image during one of a separate imaging procedure or a same imaging procedure as the comparative image. In a fourth example of the method, optionally including one or more or each of the first through third examples, the reference image is a scout image acquired with an x-ray detector and the comparative image is taken prior to the reference image during one of a separate imaging procedure or a same imaging procedure. In a fifth example of the method, optionally including one or more or each of the first through fourth examples, registering the comparative image includes pre-processing the comparative image to define a region free from artifacts in the comparative image. In a sixth example of the method, optionally including one or more or each of the first through fifth examples, the method further comprises: comparing the ROI position to a biopsy volume indicated on a display of a workstation, and, in response to the ROI being outside of the biopsy volume, instructions for repositioning the patient are displayed. In a seventh example of the method, optionally including one or more or each of the first through sixth examples, displaying the comparative image at the display screen with the instructions includes displaying one or more of text indicating how to reposition the patient, text indicating a location of the lesion relative to the desired region of the comparative image, and arrows indicating the location of the lesion relative to the desired region of the comparative image.

The disclosure also provides support for a system for digital mammography, comprising: an x-ray source in communication with a detector, a display device, and a computing device connected in communication with the display device and with the detector, the computing device including a processor and non-transitory memory storing instructions executable by the processor to: acquire a scout image of a breast, register, with the processor, the scout image to a reference image, the reference image including a first ROI identifying a position of a lesion in the reference image and collected before acquiring the scout image, generate, in response to the lesion being within a frame of the scout image and with the processor, a second ROI on the scout image identifying the position of the lesion in the scout image and indicate if the position of the lesion is within a biopsy volume, and display, in response to the lesion being outside of the frame of the scout image, a first notification on a display screen. In a first example of the system, the scout image and reference image form a pair of angulated x-ray images or the scout and reference image are contrast enhanced spectral mammography (CESM) images. In a second example of the system, optionally including the first example, the reference image is an x-ray image, an ultrasound (US) image, or a magnetic resonance imaging (MRI) image. In a third example of the system, optionally including one or both of the first and second examples, the first ROI of the reference image is placed by a clinician or computer aided diagnosis (CAD) program. In a fourth example of the system, optionally including one or more or each of the first through third examples, instructions to indicate if the position of the lesion within the biopsy volume include to display a second notification on the display screen and/or to generate an audio notification. In a fifth example of the system, optionally including one or more or each of the first through fourth examples, the first or second notifications include written instructions or symbolic instructions.

The disclosure also provides support for a system for digital mammography, comprising: an x-ray source in communication with a detector, a display device, and a computing device connected in communication with the display device and with the detector, the computing device including a processor and non-transitory memory storing instructions executable by the processor to: register one or more reference images including a first ROI to a comparative image, the first ROI indicating a position of a lesion on the one or more reference images, and indicate a position of the lesion with respect to the comparative image. In a first example of the system when the position of the lesion is within a frame of the comparative image, the position is indicated as a second ROI on the comparative image. In a second example of the system, optionally including the first example when the position of the lesion is outside the frame of the comparative image, the position is indicated as directions displayed at the display device to reposition a patient. In a third example of the system, optionally including one or both of the first and second examples, the one or more reference images and comparative image are taken using common or different imaging modalities. In a fourth example of the system, optionally including one or more or each of the first through third examples, the one or more reference images are CESM images. In a fifth example of the system, optionally including one or more or each of the first through fourth examples, the comparative image is a CESM image taken after contrast agent washout.

FIG.1shows an example configuration with relative positioning of various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being coupling, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.

As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. The terms “including” and “in which” are used as the plain-language equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

This written description uses examples to disclose the invention, including the best mode, and also to enable a person of ordinary skill in the relevant art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.