PROSPECTIVE-STUDY OF SOMATOSTATIN RECEPTOR SCINTIGRAPHY AND ITS EFFECT ON OPERATIVE OUTCOME IN PATIENTS WITH ZOLINGER-ELLISON SYNDROME

Objective To determine the relative abilities of somatostatin receptor scintigraphy (SRS) and conventional imaging studies (computed tomogra phy, magnetic resonance imaging, ultrasound, angiography) to localize gastrinomas before surgery in patients with Zollinger-Ellison syndrome (ZES) subsequently found at surgery, and to determine the effect of S RS on the disease-free rate. Summary Background Data Recent studies de monstrate that SRS is the most sensitive imaging modality for localizi ng neuroendocrine tumors such as gastrinomas. Because of conflicting r esults in small series, it is unclear in ZES whether SRS will alter th e disease-free rate, which gastrinomas are not detected, what factors contribute to failure to detect a gastrinoma, or whether the SRS resul t should be used to determine operability in patients without hepatic metastases, as recently recommended by some investigators. Methods Thi rty-five consecutive patients with ZES undergoing 37 exploratory lapar otomies for possible cure were prospectively studied. All had SRS and conventional imaging studies before surgery. Imaging results were dete rmined by an independent investigator depending on surgical findings. All patients underwent an identical surgical protocol (palpation after an extensive Kocher maneuver, ultrasound during surgery, duodenal tra nsillumination, and 3 cm duodenotomy) and postoperative assessment of disease status (fasting gastrin, secretin test imaging within 2 weeks, at 3 to 6 months, and yearly), as used in pre-SRS studies previously. Results Gastrinomas were detected in all patients at each surgery. Se venty-four gastrinomas were found: 22 duodenal, 8 pancreatic, 3 primar ies in other sites, and 41 lymph node metastases. The relative detecti on order on a per-patient or per-lesion basis was SRS > angiography, m agnetic response imaging, computed tomography > ultrasound. On a per-l esion basis, SRS had greater sensitivity than all conventional studies combined. SRS missed one third of all lesions found at surgery. SRS d etected 30% of gastrinomas less than or equal to 1.1 cm, 64% of those 1.1 to 2 cm, and 96% of those >2 cm and missed primarily small duodena l tumors. Tumor size correlated closely with SRS rate of detection. SR S did not increase the disease-free rate immediately after surgery or at 2 years mean follow-up. Conclusions SRS is the most sensitive preop erative imaging study for extrahepatic gastrinomas in patients with ZE S and should replace conventional imaging studies as the preoperative study of choice. Negative results of SRS for localizing extrahepatic g astrinomas should not be used to decide operability, because a surgica l procedure will detect 33% more gastrinomas, especially in the duoden um and in periduodenal lymph nodes, or more extensive surgery will be needed to improve post-operative disease-free rate in ZES.