Optical coherence tomography for surgical margin evaluation of excised canine cutaneous and subcutaneous tumours

Abstract

Currently, intraoperative tumour margin imaging is not routinely utilized in veterinary medicine. Optical coherence tomography (OCT) allows for real‐time assessment of tissue morphology of 1–2 mm depth. The aims of this study were (1) to compare the histologic and OCT features of excised canine skin and subcutaneous specimens, and (2) to determine the diagnostic accuracy of OCT for surgical margin evaluation. The authors hypothesized that OCT imaging would correlate well with histopathology and that OCT would be sensitive for detection of incomplete margins. Eighty dogs were prospectively enrolled. Tumours were excised, and the surgical margins were imaged using a spectral domain OCT system. The tumour type and completeness of excision were determined by histopathology. Nine blinded observers received training in OCT image interpretation and were then given a set of OCT images and videos. The observers assigned each image/video a grade from 1 (no tumour) to 4 (tumour) and the results were compared to histopathology. The overall median sensitivity and specificity of OCT imaging for detection of incomplete margins were 86.7% and 84.6%, respectively. A potential limitation is that observers had varied experience with OCT image interpretation, ranging from no prior experience to participating in a previous OCT project. OCT is sensitive for detection of incomplete margins and could be a promising real‐time surgical margin imaging modality. Further study is needed to evaluate intraoperative applications of OCT and its impact on tumour recurrence and long‐term outcome.

Defining the relevance of surgical margins. Part two: Strategies to improve prediction of recurrence risk

“…The use of OCT has been explored in a variety of canine tumours, including mammary, soft tissue sarcoma and mast cell tumours 74–76 . In these papers, the authors have explored two potential roles for OCT in the oncologic patient.…”

“…When used for other cutaneous and subcutaneous tumours, and also mammary tumours, a sensitivity and specificity of between 80% and 90% was reported 75 . In these early experiences, the learning curve for interpretation of the OCT was considered an initial limitation, and accuracy was expected to improve with increasing familiarity with this imaging technique 76 . When Artificial Intelligence was incorporated into the image acquisition pathway, the accuracy for distinguishing normal from neoplastic tissue became close to 100% 77 …”

“…34 The use of OCT has been explored in a variety of canine tumours, including mammary, soft tissue sarcoma and mast cell tumours. [74][75][76] In these papers, the authors have explored two potential roles for OCT in the oncologic patient. In the first instance, OCT was used on the tumour specimen following surgical excision as a guide to the pathologist to identify suspicious areas of the submitted specimen that would warrant histopathologic analysis (ex vivo).…”