[Intraoperative isotope-controlled probe localization after somatostatin receptor scintigraphy of occult neuroendocrine tumors].

Intraoperative gamma detection of GEP tumors with a manual probe following i.v. 111In-DTPA-D-Phe1-Pentetreotide is a new and expensive procedure. This study analyses its value in nine patients with occult lesions (undetected preoperatively). All lesions with the exception of a 8-mm liver metastasis were correctly diagnosed intraoperatively. The tumor/normal tissue ratios were in vivo 1.3 (1.1-2.0) and ex vivo 23.0 (9.4-24.0). False-positive results were obtained three times in vivo and once ex vivo. Sensitivity was 89% and specificity 57%, respectively. All lesions were successfully detected by careful surgical exploration. We conclude that intraoperative gamma detection offers little additional information over standard diagnostic procedures.