Real-time quantification during indocyanine green fluorescent-guided surgery in canine soft tissue sarcomas and mast cell tumors

The aim of this pilot study was to evaluate the feasibility and utility of real-time tumor fluorescence-guided surgery (TFGS) with near-infrared fluorescence indocyanine green (NIRF-ICG) for the removal of spontaneous soft tissue sarcoma (STS) and mast cell tumor (MCT) at first presentation or recurrence in dogs. A dose of 0.5 mg/kg of ICG was administered 24 h before surgery, with a tumor-to-background (TBR) and signal-to-background ratio (SBR) cut-off of 2. Twenty-four dogs with 28 tumors (14 MCTs and 14 STSs) were included. TFGS was feasible in all STSs and in 11/14 MCTs. The median TBR of STS and MCT was 13 (IQR 26–9.4) and 5.8 (IQR 19–3.6) respectively. Considering the residual fluorescence in the wound bed and the histopathological results the sensitivity and specificity of NIRF-ICG excision were 80% and 78% in STS and 60% and 50% in MCT, respectively. Overall, resection was extended during TFGS in 64% of STSs and 55% of MCTs. These results convey the feasibility of TFGS with NIRF-ICG in canine STS surgical extirpation. However, the findings indicate more limited performance in MCT. The different performance in STS and MCT needs to be investigated in a larger population.