Feasibility of Radio-Guided Surgery for Neuroendocrine Tumours Using 99mTc-HYNIC TOC

Abstract

Introduction and aim: Intra-operative localization of small functioning pancreatic neuroendocrine tumours and liver metastases can be challenging. We here demonstrate the feasibility, technical protocol, utility and safety aspect of intra-operative tumour localization in using 99mTc-HYNIC-TOC. Materials and methods: 6 patients diagnosed with GEP-NET with or without liver secondaries were included in this study (5 males, 1 female). 3 patients had primary NET of the pancreas of which 2 patients had in additional liver metastases, 1 patient had distal ileal NET with loco-regional nodes and liver metastases, 1 patient had primary nodal gastrinoma with no evidence of any pre-operative lesions in duodenum/pancreas, 1 patient had bilobar liver secondaries from metastatic rectal NET. All patients were injected with 925-1110 MBq of 99mTc-HYNIC-TOC IV and surgery was done after 18-20 hours later on day 2. Intra-operative tumour localization was done using a hand-held high sensitivity gamma probe. Results: Total 23 lesions were localised intra-operatively and confirmed on histopathological as NET. Of these, were 10 in the liver, 3 in pancreas, 9 in nodes and 1 in the distal ileum. Of these 23 lesions, 19 were localized pre-operatively on imaging and by non-aided visualization by surgeon and 4 lesions (17%) were exclusively seen on intra-op localization using probe. These included 2 nodes and 2 liver lesions, all of which measured less than 1cm. Conclusion: Radio-guided surgery gastro-entero-pancreatic neuroendocrine tumours using indigenous 99mTc-HYNIC-TOC is safe and feasible in clinical setting and promises to improve precision of intra-operative localization of lesions in liver and pancreas.