INTRAOPERATIVE GAMMA-PROBE DETECTION OF N EUROENDOCRINE TUMORS

Previous studies of the intraoperative use of a hand-held gamma probe to localize metastases and primary tumors of colorectal cancer have sh own improved assessment of tumor spread and changes in surgical manage ment based on added information gained by radioimmunoguided surgery. F ollowing the injection of 180 MBq [In-111-DTPA-D-Phe(1)]-pentetreotide and/or 500 MBq Tc-99m-dimercaptosuccinic acid (both for dual-radionuc lide scintigraphy) preoperative somatostatin receptor imaging [11 pati ents with GEP tumors] and dual-radionuclide scintigraphy (8 patients w ith relapsing medullary thyroid carcinomas) was performed. One patient with a metastasizing pheochromocytoma underwent (123)J-MIB g scintigr aphy. Results were combined with the information obtained from convent ional imaging modalities. Intraoperative radiodetection was performed 24 hours after administration of [In-111-DTPA-D-Phe(1)]-pentetreotide or 4 hours following the injection of Tc-99m(V)DMSA using a hand-held gamma probe (Tee Probe 2000, Stratec, FRG). Intraoperative gamma count ing localized 39 somatostatin receptor positive lesions of GEP tumors whereas preoperative receptor imaging visualized 81 %, surgical palpat ion 41 % and radiological imaging modalities localized only 31 %. In 8 patients with recurrent medullary thyroid carcinoma the surgeon was s uccessful in localizing and removing 18 tumor lesions by the help of t he gamma probe. Dual-radionuclide scintigraphy revealed 77% (Octreosca n(R) 5/18; Tc-99m-V-DMSA 9/18), surgical palpation 55 % and convention al imaging methods (CT, sonography.) only 38 % of all lesions detected intraoperatively by the hand-held gamma probe. In summary, this preli minary data show that intraoperative hand-held gamma probe detection o f microscopic and occult endocrine tumors is feasible and more sensiti ve than external scintigraphy and conventional imaging.