INTRAARTERIAL CALCIUM STIMULATION AND INTRAOPERATIVE ULTRASONOGRAPHY IN THE LOCALIZATION AND RESECTION OF INSULINOMAS

Background. Standard imaging studies (computed tomography, magnetic re sonance imaging somatostatin receptor scintigraphy, ultrasonography, a nd angiography) correctly localize insulinomas in less than 50 % of pa tients and provide no information about the feasibility of enucleation based on proximily of tumor to pancreatic duct. We reviewed our exper ience with intraarterial calcium stimulation (Ca-Stim) and intraoperat ive ultrasonography (IOUS) to localize and guide management of insulin omas. Methods. Thirty-six patients (14 men, 22 women, median age 44 ye ars) with insulinomas were treated between August 1989 and June 1996. Preoperative imaging studies were obtained. Patients underwent abdomin al exploration with IOUS. Fourteen were evaluated by a surgeon blinded to preoperative imaging results. Results. Tumors (4 to 50 mm) were re sected by enucleation (67 %) or partial pancreatectomy (33 %); all wer e cured. Sensitivities of computed tomography, magnetic resonance imag ing somatostatin receptor scintigraphy, ultrasonography, angiography, and Ca-Stim in localizing insulinomas were 24 %, 45 %, 17%, 13 %, 43 % , and 94 %, respectively. Tumors were identified by blinded surgical e xploration with IOUS in 12 of 14 patients (86 %). Conclusions. All ins ulinomas were identified before operation; however, sensitivity of ind ividual noninvasive tests was low (less than 50 %). In contrast, Ca-St im was correct in 94 % of cases, thus allowing a focused pancreatic ex ploration and obviating-use of blind distal pancreatectomy. IOUS can t hen De used to guide safe enucleation.