Value of intra-arterial calcium stimulated venous sampling for regionalization of pancreatic insulinomas

Background. Intra-arterial calcium stimulation with hepatic venous sampling (ASVS) for insulin gradients has been reported to be the most sensitive preoperative localizing technique for insulinomas. We reviewed our experience with ASVS to localize and guide the treatment of insulinomas over the past decade. Methods. Eighteen patients who underwent ASVS before surgical exploration for insulinoma were studied. The accuracy of ASVS was compared with intraoperative findings and other localizing studies. Results. There were no complications arising from the procedures. A more than 2-fold step-zip in insulin level 30 to 60 seconds after injection to at least 1 feeding artery was observed in 16 patients. Fourteen of the IB solitary tumors (87.5%) were correctly located; 100% (6/6 tumors) at the head and 80% (8/10 tumors) at the body/tail. The overall accuracy of this test was 89%, compared with 11%, 33%, 38%, and 63% of ultrasonography, computed tomography, magnetic resonance imaging, and endoscopic ultrasonography respectively. Six enucleations and 10 distal resections were performed, which included 2 laparoscopic procedures. The combination of int intraoperative ultrasonography with preoperative ASVS identified all tumors. Conclusions. ASVS is the most accurate preoperative localization tool for the localization of insulinomas and, in combination with intraoperative ultrasonography, can enhance surgical success.