Role of the intra-arterial calcium stimulation test in the preoperative localization of insulinomas.

The aim of this study was determination of the significance of the arterial stimulation test with venous sampling (ASVS) in the preoperative localization of insulinoma. Eleven patients with endogenous hyperinsulinism underwent preoperative transabdominal US, spiral computer tomography (spiral CT), MRI, endoscopic ultrasound (EUS) as well as angiography (DSA) combined with ASVS. The results were compared with intraoperative findings, intraoperative ultrasound (IOUS) and histopathology. There were no complications related to the ASVS test. In 11 patients the tumor could be localized with the various modalities as follows: US 1 of 11 (9%), MRI 3 of 10 (30%), spiral CT 4 of 11 (36%), EUS 5 of 10 (50%), DSA 8 of 11 (73%), and ASVS 10 of 11 (91%). In 2 patients the tumors were intraoperatively neither palpable nor detectable by IOUS, and consequently the intraoperative management was governed by information provided by DSA combined with the ASVS test. Ten patients had solitary benign insulinomas and 1 patient with multiple endocrine neoplasia I had two tumors adjacent to each other in the pancreatic tail. Arterial stimulation test with venous sampling was the most sensitive preoperative test for regionalizing the insulinoma in our set of patients. It can be performed safely in the course of a regular DSA examination and may affect intra-operative management in patients in whom the tumors are not detectable by palpation or IOUS.