Intrapatient application of lymphoscintigraphy and near-infrared fluorescence in canine and feline sentinel lymph node mapping and removal.

Abstract

BACKGROUND: No data regarding near-infrared fluorescence (NIRF) with indocyanine green and its comparison with lymphoscintigraphy are available for sentinel lymph node identification in canine and feline solid malignant tumors. This study compares both techniques in sentinel lymphocentrums mapping and surgical guided sentinel lymph node extirpation. RESULTS: Fifty-four animals with 60 tumors were included, and the combined use of lymphoscintigraphy and NIRF was applied: 80 sentinel lymphocentrums were surgically explored, and 113 sentinel lymph nodes were extirpated. This combination allowed the detection of at least one sentinel lymphocentrum and sentinel lymph node per each tumor. During mapping, the sentinel lymphocentrum detection rate with NIRF was 93%, similar to lymphoscintigraphy with a handheld intraoperative gamma probe (92%). No significant differences among techniques were observed in the surgical guided exploration phase, except that the number of fluorescent sentinel lymph nodes was significantly higher than radioactive ones, and the number of detected metastatic lymph nodes was comparable among the techniques. Surgeons subjectively considered the intraoperative gamma probe more helpful in 46.5% of sentinel lymph node extirpations, NIRF more helpful in 24.2%, and both techniques equally helpful in 29.3% of cases. Overall, they deemed the use of intraoperative gamma probe superior to NIRF for axillary lymphadenectomies and NIRF superior to lymphoscintigraphy for head and neck lymphadenectomies. CONCLUSIONS: Despite some differences between the techniques, NIRF with indocyanine green can be considered a practical and viable alternative to lymphoscintigraphy for sentinel lymphocentrum mapping and guided sentinel lymph node removal in small animal oncologic practice, particularly where lymphoscintigraphy is not accessible.