Abstract P2-03-11: In situ imaging of the tumor cavity during breast lumpectomy using optical coherence tomography
Authors: Boppart SA , Nolan RM , Erickson-Bhatt SJ , Shemonski ND , Adie SG , Putney J , Darga D , McCormick DT , Cittadine A , Marjanovic M , Zysk AM , Chaney EJ , Monroy GL , South FA , Carney PS , Cradock KA , Liu ZG , Ray PS 
Published: August 2014

Abstract
Re-operation rates for breast lumpectomy procedures are exceedingly high, often over 30%, depending on the institution and surgical technique. Because current standard-of-care relies on post-operative histopathology to provide a microscopic view and assessment of surgical margins, there has been great interest in developing new imaging solutions to visualize tissues intraoperatively with high-resolution, and provide real-time feedback on the margin status. While it is possible to use a variety of microscopic imaging methods in the operating suite, including frozen-section histology, touch-prep cytology, confocal or scattering-based microscopy, all these techniques are limited to visualizing margins on ex vivo resected specimens, and do not provide a means for visualizing the in situ tumor cavity for evidence of positive margins or residual disease.
Optical coherence tomography (OCT) is a high-resolution, real-time, optical biomedical imaging technology that is the optical analogue to ultrasound imaging, except images are based on backscattered near-infrared light. OCT is capable of performing optical biopsies of in situ tissue at resolutions that approach those in histopathology. With the use of an advanced computed imaging technique called ISAM (Interferometric Synthetic Aperture Microscopy), even higher imaging resolution over larger depths is possible, commensurate with the depths (1-2 mm) visualized by pathologists to determine negative, close, or positive margins. Past studies by our group and others have demonstrated the feasibility of intraoperative OCT for assessing tumor margin and lymph node status during breast cancer surgery, but to date, all studies have been performed on resected lumpectomy tissue.
In this study, we report the development of a novel handheld surgical imaging probe that enables 2-D and 3-D OCT/ISAM imaging of the in situ tumor cavity, in addition to the margins of excised specimens. To date, this handheld OCT/ISAM probe has been used in 10 breast cancer surgeries where both in situ and ex vivo imaging was performed. Four of these cases involved in situ imaging of the cavity margin after a suspicious area was visually and tactically identified, and was subsequently resected, followed by ex vivo imaging and validating post-operative histopathology. Representative cases included fibroadipose tissue, fibroadenomas, and high-grade ductal carcinoma in situ.
Distinct microstructural features identified on OCT/ISAM and confirmed with histopathology demonstrate that this technique can visualize the in situ tumor cavity, as well as the surgical margins on resected specimens, with micron-scale resolution. OCT/ISAM has the potential to determine margin status in real-time during the surgical procedure, when further surgical resection to establish clear margins and reduce re-operation rates is possible.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-03-11.