Integrated Widefield Imaging and Spectroscopy System

Tumor recurrence following surgery is a common and unresolvedmedical problem of great importance since surgery is the most widely used treatment for solid-mass tumors worldwide. A contributing factor to tumor recurrence is the presence of residual tumor remaining at or near the surgical site following surgery. Goal: The primary objective of this study was to develop and evaluate an image-guided surgery system based on a near infrared, handheld excitation source and spectrograph in combination with a widefield video imaging system. Methods: This system was designed to detect the fluorescence of near infrared contrast agents and, in particular, indocyanine green. The imaging system was evaluated for its optical performance and ability to detect the presence of indocyanine green in tumors in an ectopic murine tumor model as well as in spontaneous tumors arising in canines. Results: In both settings, an intravenous indocyanine green infusion provided tumor contrast.

In both the murine models and surgical specimens from canines, indocyanine green preferentially accumulated in tumor tissue compared to surrounding normal tissue. The resulting contrast was sufficient to distinguish neoplasia from normal tissue; in the canine surgical specimens, the contrast was sufficient to permit identification of neoplasia on the marginal surface of the specimen. Conclusion: These results demonstrate a unique concept in image-guided surgery by combining local excitation and spectroscopy with widefield imaging. Significance: The ability to readily detect ICG in canines with spontaneous tumors in a clinical setting exemplifies the potential for further clinical translation; the promising results of detecting neoplasia on the marginal specimen surface underscores the clinical utility.