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The invasive, locally aggressive nature of feline injection-site sarcomas (FISSs) poses a unique challenge for surgeons to obtain complete margins with surgical excision. Optical coherence tomography (OCT), an imaging technology that uses light waves to generate real-time views of tissue architecture, provides an emerging solution to this dilemma by allowing fast, high-resolution scanning of surgical margins. The purpose of this study was to use OCT to assess surgical margins of FISS and to evaluate the diagnostic accuracy of OCT for detecting residual cancer using six evaluators of varying experience. Five FISSs were imaged with OCT to create a training set of OCT images that were compared with histopathology. Next, 25 FISSs were imaged with OCT prior to histopathology. Six evaluators of varying experience participated in a training session on OCT imaging after which each of the evaluators was given a dataset that included OCT images and videos to score on a scale from cancerous to non-cancerous. Diagnostic accuracy statistics were calculated. The overall sensitivity and specificity for classification of OCT images by evaluators were 78.9% and 77.6%, respectively. Correct classification rate of OCT images was associated with experience, while individual sensitivities and specificities had more variation between experience groups. This study demonstrates the ability of evaluators to correctly classify OCT images with overall low levels of experience and training and also illustrates areas where increased training can improve accuracy of evaluators in interpretation of OCT surgical margin images.

Histopathologic surgical margin assessment in veterinary patients is an imprecise science with assessment limited to a small proportion of the surgical margin due to time and finances. Incomplete excision of canine mast cell tumours (MCTs) alters treatment recommendations and prognosis. Optical coherence tomography (OCT) is a novel imaging modality that has been reported in a single veterinary study for surgical margin assessment. Twenty-five dogs with 34 MCTs were enrolled in a prospective pilot-study to assess the imaging characteristics of canine MCTs with OCT and to evaluate the feasibility and utility of OCT-guided histopathology. All dogs underwent routine surgical excision of MCTs. OCT imaging was used to assess the entire surgical margin prior to placement in formalin. Either normal areas or areas suspected of incomplete MCT excision were inked. Standard histopathologic sectioning and tangential sectioning of inked areas were performed and compared to OCT results. OCT identified MCT near the surgical margin in 10 of 26 specimens (38.4%). Four specimens suspicious for incomplete margins on OCT had incomplete MCT excision that was missed on standard histopathologic sectioning. Six specimens had OCT-guided sections taken as suspicious, which did not show MCT on histopathology. OCT-guided pathology sections were able to detect incompletely excised MCT near the surgical margin with a sensitivity of 90% and specificity of 56.2% in this preliminary study. OCT imaging shows promise for guiding pathologists to areas of interest to improve the diagnostic accuracy of surgical margin assessment in excised canine MCTs.