<scp>SHINE</scp> – Validation of Near Infrared Fluorescence Lymphography Against Lymphoscintigraphy for Sentinel Lymph Node Biopsy in Dogs With Mast Cell Tumours

Lymphoscintigraphy is the gold standard among sentinel lymph node (SLN) mapping techniques. Unfortunately, lymphoscintigraphy is not readily accessible, leading to the need for validation of alternative techniques. The aim of this study is to compare near-infrared fluorescence lymphography (NIRF-L) with lymphoscintigraphy for SLN resection in MCT and assess the impact of intraoperative NIRF guidance. Forty-eight dogs with 60 MCT were included in this prospective, blinded, randomised controlled trial. Dogs underwent preoperative lymphoscintigraphy and were then randomised into two groups: in the treatment group (n = 30) intraoperative NIRF-L was performed; in the control group (n = 30) no intraoperative guidance was implemented. Detection rate, concordance, sensitivity, and negative predictive values were recorded for NIRF-L and lymphoscintigraphy. Surgical time and length of surgical incision were compared between treatment and control groups with the Wilcoxon test (5% significance). Detection rate was 100% for NIRF-L and 98% for lymphoscintigraphy. Discordance occurred in one case. Sensitivity of NIRF-L was 93.7% (95% C.I. 74.3%-99.3%) and negative predictive value ranged between 91.1% and 98.6% with a prevalence of nodal metastases of 61% and 18%. Based on the overlapping of the confidence intervals, NIRF-L was not statistically different to lymphoscintigraphy for sensitivity. Lymphadenectomy was unsuccessful in 4/30 (13%) cases in the control group. Surgical time and incision were significantly shorter in the treatment group (p < 0.001; p = 0.001). Based on our results, NIRF-L is a valid alternative to lymphoscintigraphy for SLN removal in MCT. Moreover, it improves the success of lymphadenectomy, reduces surgical time, and incision length compared to an unguided technique.