Prospective Study of Somatostatin Receptor Scintigraphy and its Effect on Operative Outcome in Patients With Zollinger-Ellison Syndrome

Abstract

ObjectiveTo determine the relative abilfties of somatostatin receptor scintigraphy (SRS) and conventional imaging studies (computed tomography, magnetic resonance imaging, uftrasound, angiography) to localize gastrinomas before surgery in patients with Zollinger-Ellison syndrome (ZES) subsequently found at surgery, and to determine the effect of SRS on the disease-free rate. Summary Background DataRecent studies demonstrate that SRS is the most sensitive imaging modality for localizing neuroendocrine tumors such as gastrinomas. Because of conflicting results in small series, it is unclear in ZES whether SRS will alter the disease-free rate, which gastrinomas are not detected, what factors contribute to failure to detect a gastrinoma, or whether the SRS result should be used to determine operability in patients without hepatic metastases, as recently recommended by some investigators. MethodsThirty-five consecutive patients with ZES undergoing 37 exploratory laparotomies for possible cure were prospectively studied. All had SRS and conventional imaging studies before surgery. Imaging results were determined 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 transillumination, 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. ResultsGastrinomas were detected in all patients at each surgery. Seventy-four gastrinomas were found: 22 duodenal, 8 pancreatic, 3 primaries in other sites, and 41 lymph node metastases. The relative detection order on a per-patient or perlesion basis was SRS > angiography, magnetic resonance imaging, computed tomography > ultrasound. On a per-lesion basis, SRS had greater sensitivity than all conventional studies combined. SRS missed one third of all lesions found at surgery. SRS detected 30% of gastrinomas -1.1 cm, 64% of those 1.1 to 2 cm, and 96% of those >2 cm and missed primarily small duodenal tumors. Tumor size correlated closely with SRS rate of detection. SRS did not increase the disease-free rate immediately after surgery or at 2 years mean follow-up. ConclusionsSRS is the most sensitive preoperative imaging study for extrahepatic gastrinomas in patients with ZES and should replace conventional imaging studies as the preoperative study of choice. Negative results of SRS for localizing extrahepatic gastrinomas should not be used to decide operability, because a surgical procedure will detect 33% more gastrinomas than SRS. SRS does not increase the disease-free rate. In the future, more sensitive methods to detect small gastrinomas, especially in the duodenum and in periduodenal lymph nodes, or more extensive surgery will be needed to improve the postoperative disease-free rate in ZES.228

Frequency and characterization of gastro–entero–pancreatic neuroendocrine tumor patients with high-grade of uptake at somatostatin receptor scintigraphy

“…SRS heterogeneity may also reflect technical issues related to the size of each tumor focus, their anatomical location, and/or the physical modality of detection, may also have some influence. The absence of uptake at SRS in NEN, in 17% of patients, is in the 6-33% range of previous studies (Krenning et al 1993, Panzuto et al 2003, Dromain et al 2005, and in up to 80% in case of localized duodenopancreatic tumors of !2 cm in size (Alexander et al 1998). The influence of the size was again confirmed in our study as a positive correlation was found between the maximum diameter of LM and high uptake at SRS.…”

The Role of 68Ga-DOTATATE PET/CT in Suspected Neuroendocrine Tumors

“…In another study of 20 patients with the clinical suspicion of gastrinoma or insulinoma, octreotide was of high value in the detection of gastrinomas (sensitivity, 86%) but had a limited sensitivity (14%) in insulinomas (17). Furthermore, in a series of patients with ZollingerEllison syndrome, octreotide was more sensitive than conventional imaging methods but missed one third of all surgically confirmed gastrinomas (18). The present encour-FIGURE 3.…”

Management of the Zollinger–Ellison syndrome in patients with multiple endocrine neoplasia type 1

“…For insulinomas, which are almost always intrapancreatic, endoscopic ultrasound appears to have the greatest sensitivity [62] whereas for gastrinomas it remains SRS. It is presently unclear that any methodology will localize the small duodenal gastrinomas in MEN-1, which is where 80% are found in these patients (Table 2) [63][64][65].…”