Medical hyperspectral imaging to facilitate residual tumor identification during surgery

Introduction: Adequate evaluation of breast tumor resection at surgery continues to be an important issue in surgical care, as over 30% of postoperative tumors recur locally unless radiation is used to destroy remaining tumor cells in the field. Medical Hyperspectral Imaging (MHSI) delivers near-real time images of biomarkers in tissue, providing an assessment of pathophysiology and the potential to distinguish different tissues based on spectral characteristics. Method: We have used an experimental DMBA-induced rat breast tumor model to examine the intraoperative utility of MHSI, in distinguishing tumor from normal breast and other tissues. Rats bearing tumors underwent surgical exposure and MHSI imaging, followed by partial resection of the tumors, then MHSI imaging of the resection bed, and finally total resection of tumors and of grossly normal-appearing glands. Resected tissue underwent gross examination, MHSI imaging, and histopathological evaluation. Results: An algorithm based on spectral characteristics of tissue types was developed to distinguish between tumor and normal tissues. Tissues including tumor, blood vessels, muscle, and connective tissue were clearly identified and differentiated by MHSI. Fragments of residual tumor 0.5 - 1 mm in size intentionally left in the operative bed were readily identified. MHSI demonstrated a sensitivity of 89% and a specificity of 94% for detection of residual tumor, comparable to that of histopathological examination of the tumor bed (85% and 92%, respectively). Conclusion: We conclude that MHSI may be useful in identifying small residual tumor in a tumor resection bed and for indicating areas requiring more extensive resection and more effective biopsy locations to the surgeon. 3