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As breast cancer screening rates increase, smaller and more numerous lesions are being identified earlier, leading to more breast-conserving surgical procedures. Achieving a clean surgical margin represents a technical challenge with important clinical implications. Optical coherence tomography (OCT) is introduced as an intraoperative high-resolution imaging technique that assesses surgical breast tumor margins by providing real-time microscopic images up to 2 mm beneath the tissue surface. In a study of 37 patients split between training and study groups, OCT images covering 1 cm2 regions were acquired from surgical margins of lumpectomy specimens, registered with ink, and correlated with corresponding histologic sections. A 17-patient training set used to establish standard imaging protocols and OCT evaluation criteria showed that areas of higher scattering tissue with a heterogeneous pattern were indicative of tumor cells and tumor tissue in contrast to lower scattering adipocytes found in normal breast tissue. The remaining 20 patients were enrolled into the feasibility study. Of these lumpectomy specimens, 11 were identified with a positive or close surgical margin and 9 were identified with a negative margin under OCT. Based on histologic findings, 9 true positives, 9 true negatives, 2 false positives, and 0 false negatives were found, yielding a sensitivity of 100% and specificity of 82%. These results show the potential of OCT as a real-time method for intraoperative margin assessment in breast-conserving surgeries. [Cancer Res 2009;69(22):8790–6]

During breast-conserving surgeries, axillary lymph nodes draining from the primary tumor site are removed for disease staging. Although a high number of lymph nodes are often resected during sentinel and lymph-node dissections, only a relatively small percentage of nodes are found to be metastatic, a fact that must be weighed against potential complications such as lymphedema. Without a real-time in vivo or in situ intraoperative imaging tool to provide a microscopic assessment of the nodes, postoperative paraffin section histopathological analysis currently remains the gold standard in assessing the status of lymph nodes. This paper investigates the use of optical coherence tomography (OCT), a high-resolution real-time microscopic optical-imaging technique, for the intraoperative ex vivo imaging and assessment of axillary lymph nodes. Normal (13), reactive (1), and metastatic (3) lymph nodes from 17 human patients with breast cancer were imaged intraoperatively with OCT. These preliminary clinical studies have identified scattering changes in the cortex, relative to the capsule, which can be used to differentiate normal from reactive and metastatic nodes. These optical scattering changes are correlated with inflammatory and immunological changes observed in the follicles and germinal centers. These results suggest that intraoperative OCT has the potential to assess the real-time node status in situ, without having to physically resect and histologically process specimens to visualize microscopic features.

Breast cancer continues to be one of the most widely diagnosed forms of cancer in women and the second leading type of cancer deaths for women. The metastatic spread and staging of breast cancer is typically evaluated through the nodal assessment of the regional lymphatic system, and often this is performed during the surgical resection of the tumor mass. The recurrence rate of breast cancer is highly dependent on several factors including the complete removal of the primary tumor during surgery, and the presence of cancer cells in involved lymph nodes. Hence, developing means to more accurately resect tumor cells, along with the tumor mass, and ensure negative surgical margins, offers the potential to impact outcomes of breast cancer. The use of diffuse optical tomography has been applied for screening optical mammography applications as an alternative to standard x-ray mammography. The use of coherence ranging and coherent optical imaging in breast tissue has also found numerous applications, including intra-operative assessment of tumor margin status during lumpectomy procedures, assessment of lymph node changes for staging metastatic spread, and for guiding needle-biopsy procedures. The development, pre-clinical testing, and translation of techniques such as low-coherence interferometry (LCI) and optical coherence tomography (OCT) into clinical applications in breast cancer is demonstrated in these feasibility studies.