Intraoperative Digital Specimen Tomosynthesis – Early Report Cary S. Kaufman1,2, Laurie Hill2, Rebecca Caro3, Sid Nix3, Karen Zacharias3, Erik Evans3, Carol Mahon3, Karen Ness3, Nancy Schnell3 1University Bellingham Abstract: OBJECTIVE: About 75% of newly diagnosed breast cancers are not palpable and require image localization to remove the target lesion via lumpectomy. It is an ASBS standard to have image confirmation of an image guided excision. To facilitate confirmation of lesion excision, digital specimen mammography devices were developed to reside in the operating room so that surgeons might obtain immediate image confirmation. If the intraoperative images demonstrated the targeted lesion had a close margin, immediate re-excision could be performed saving a return trip to the operating room. Despite the availability of twodimensional digital specimen mammography (2D), the re-excision rate for lumpectomy remains significant. Specimen tomosynthesis (3D) has recently been developed to provide a more detailed image than standard 2D specimen mammography. Highly detailed consecutive image slices of the lumpectomy specimens can be immediately reviewed in the operating room providing the surgeon with an increased level of scrutiny. Serial scrolled images can follow calcifications and masses through the specimen to define adequacy of excision. METHODS: A consecutive series of 22 breast cancer patients underwent intraoperative specimen imaging with both 2D and 3D imaging. Data recorded for each specimen on each device included 1) accuracy of identification of target lesion, 2) time required to produce comparable images of the target lesion, 3) ease of forwarding images via PACS to radiology for review, 4) predicted closest margin according to each specimen imaging device compared with final pathologic measured margin, 5) ease of use by the surgeon and/or nurse, and 6) comparison cost and maintenance of device. RESULTS: The central focus of all 22 lesions were accurately identified with both 2D and 3D. After a short learning curve we were able to see details on the tomosynthesis images not clearly shown on the 2D unit. Viewing individual slices with 3D identified some spiculated masses and architectural distortions not well visualized with 2D. The location of closest margin was more specific with the 3D device due to “Z-axis” measurements which obtain the vertical distance of the target within the specimen. Although marginal calcifications or marking clips were seen on both devices, the spatial relationship of these targets at the edge of the specimen provided by the 3D “Z-axis” was superior to the 2D orthogonal views. Although the time taken to obtain the 3D image was 72 seconds longer than a single image with the 2D device (103 vs. 31 seconds), this was equal to the time taken to obtain the two orthogonal images using the 2D device. Ease of use was equal with both 2D and 3D for both nurses and physicians. There were too few patients with positive margins in this initial group of patients to assess a difference in intraoperative positive margin prediction. Cost and maintenance analysis was unable to be performed due to variable pricing information for both 2D and 3D devices. CONCLUSIONS: Our initial experience with 3D tomosynthesis of lumpectomy specimens demonstrate clearer images and increased information available for the breast surgeon. Research is planned to further examine the added value of high resolution tomosynthesis in breast surgery. of Washington Department of Surgery, 2Bellingham Regional Breast Center, 3Bellingham Ambulatory Surgery Center Steps to obtain specimen tomosynthesis: 1) 2) 3) 4) 5) 6) 7) Center specimen in device. System automatically defines highest point of specimen. Exposure button to obtain images View consecutive slices in video format or view single images. Use slices to view Z-axis. Export or send to PACS (multiple formats available). Intraoperative review and immediate re-excision as needed. Overall Time = 2 minutes 2D Tomosynthesis slice 3D 3D 39mm 17 /39mm 5 /39mm “Z-axis” Provides Exact Location of Positive Margin 1) Left 2D view of multiple calcifications with left side positive margins 2) Center 3D shows inferior left 3) side positive margin at 5 mm from base of specimen Right 3D shows superior left side positive margin at 17 mm from base of specimen 2D 3D Summary • • • • • Obtains both 2-D and 3-D images Time from image capture to 3-D ~ 100 seconds Ease of use similar to 2D systems Provides anatomic orientation of close margins using Z-axis Confirms removal of vague mammographic findings Architectural Distortion Clarified by 3D: 4) Left 2D image demonstrates architectural distortion 5) Right 3D image demonstrates spiculations on slice at 10 mm from specimen base
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