Real-life intrapatient application of lymphoscintigraphy and near-infrared fluorescence in canine and feline sentinel lymph node mapping and removal

Introduction: Few data regarding near-infrared fluorescence (NIRF) with indocyanine green (ICG) and its comparison with lymphoscintigraphy (LPS) are available for sentinel lymph node (SLN) removal in canine and feline malignancies. This study aims to compare both techniques in two phases: sentinel lymphocentrums (SLC) mapping and surgical guided SLN extirpation. Materials and methods: Dogs and cats with malignancies, amenable to surgery, were prospectively enrolled to SLN removal guided by both techniques. Planar-LPS with and without handled intraoperative gamma probe (HIGP) and NIRF were compared in SLC detection. Intraoperatively, HIGP and NIRF were compared in SLN detection and subjectively surgical aid was recorded by the surgeons. Results: Fifty dogs and 4 cats with 60 tumors were included, 80 SLCs were explored and 113 SLNs extirpated. During mapping, the SLC detection rate NIRF-ICG (93%) was higher than preoperative planar-LPS alone (80%) but similar when HIGP was added (92%). No significant differences among techniques were observed in the surgical guided exploration phase, except that the number of fluorescent SLNs was significantly higher than radioactive SLNs, but this was not associated with an increased metastasis detection. Surgeons subjectively considered HIGP more helpful in 46,5%, NIRF in 24,2%, and equal in 29,3% SLNs research. Surgeons considered HIGP more helpful in axillary lymphadenectomies and NIRF-ICG in head and neck SLNs extirpation. Conclusions: In conclusion, NIRF-ICG and LPS showed comparable performance and NIRF-ICG can be considered a viable alternative to LPS for peripheral SLC mapping and SLN removal in daily clinical practice.