Room: Track 4
Purpose: To demonstrate the utility of a multi-modal system using micro-focus x-ray computed tomography (micro-CT) and optical structured light imaging (SLI) to reduce positive margins during breast conserving surgery (BCS) in a surgical patient trial. Patients undergoing BCS may require additional surgery if malignancy is found at the margin of the tissue resected. Margin status is determined days after the operation and 15-35% of patients require additional operations.
Methods: Specimens are imaged using a 50kVp, 1 mA lateral micro-CT system and integrated SLI of two margins at sub-surface depth (<1mm). The SLI system provides scatter measurements at multiple wavelengths (490-700nm) and spatial frequencies (0-1.37mm-1).
An ongoing clinical trial at Dartmouth Hitchcock Medical Center aims to image one hundred specimens intraoperatively (ClinicalTrials.gov Identifier: NCT04257799). In addition to this, the surgeon notes their determination of margin status based on 2D intraoperative mammography and palpation. Both these and micro-CT/SLI results are compared to final margin status to see if more positive margins are caught.
Results: Imaging takes ten minutes. Preliminarily data shows an increase in positive margins caught compared to standard-of-care tools. The presence of blood and complex specimen geometry has not made a significant impact on the ability to determine margin status.
Imaging has not been shown to impede clinicians and provides minimal additional risk to patients.
Conclusions: This is an ongoing trial so conclusions about the efficacy of the modality will not be made. However, a previous study has shown a statistically significant ability to separate tissue types on slices of fresh tissue post-operatively.
Wide-field SLI and volumetric micro-CT of entire specimens is completed rapidly. Imaging scatter signatures has made the effects of blood negligible. Custom optically-clear specimen holders have reduced the effects of specimen geometry. These provide flat imaging surfaces, mild compression, and fiducial markers to maintain anatomic orientation.