Intraoperative Digital Specimen Tomosynthesis

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