Localization of Benign Insulinomas Using Glucagon-like Peptide-1 Receptor (GLP1-R) SPECT/CT and PET/CT and MRI in a Prospective Clinical Study
Presentation Number: OR22-6
Date of Presentation: April 1st, 2017
Kwadwo Antwi1, Melpomeni Fani1, Tobias Heye1, Guillaume P Nicolas2, Elmar Merkle3, Jean Claude Reubi4, Beat Gloor5, Damian Wild1 and Emanuel R Christ*6
1University Hospital of Basel, Basel, Switzerland, 2UniversityHospital of Basel, Basel, Switzerland, 3University of Basel Hospital, Basel, Switzerland, 4University of Bern, Bern, Switzerland, 5University Hospital of Bern, Inselspital, Bern, Switzerland, 6University Hospital of Berne, Berne, Switzerland
The aim of our study is to compare the detection rate of GLP-1R PET/CT, GLP-1R SPECT/CT and standardized contrast enhanced 3T MRI in patients with a biochemically proven endogenous hyperinsulinemic hypoglycemia highly suspicious for an insulinoma. Preliminary results of an ongoing study are reported.
40 patients (31 females, 9 males, age range 18-80 years, mean 48 years) with neuroglycopenic symptoms due to endogenous hyperinsulinemic hypoglycemia were enrolled (ClinicalTrials.gov, NCT02127541). A standardized contrast enhanced 3T MRI was performed. Afterwards the patients received a SPECT/CT at 4 and 72 hours after injection of 111In-DOTA-exendin-4 and a PET/CT 2,5 hours after injection of 68Ga-DOTA-exendin-4 in a randomized order. Three independent blinded nuclear medicine physicians and three independent blinded radiologists reviewed the scans. Standard of comparison was the histological diagnosis after surgery.
Previously performed cross-sectional imaging (CT/MRI) was negative or not conclusive in 27/40 (68%) of patients.
29 patients have been operated. In this collective, the histological diagnosis of a benign insulinoma was confirmed in 25 patients, 1 patient had adult islet cell hyperplasia. In 1 patient both intraoperative palpation as well as the histological diagnosis did not confirm an insulinoma. In 2 patient symptoms of endogenous hypoglycemia ceased postoperative but histological diagnosis did not confirm the diagnosis of a benign insulinoma or nesidioblastosis. Only these two patients were excluded from evaluation as the final diagnosis remained unclear.
Two patients refused surgery. Three patients are awaiting surgery. In five patients PET/CT, SPECT/CT as well as the previous performed conventional imaging did not find any suspicious lesion and were thus not operated up to date. One patient showed signs of malignancy in contrast enhanced MRI, thus did not meet the inclusion criteria and did not receive surgery up to date.
In this interim analysis of 27 operated patients PET/CT patients showed an overall pooled sensitivity of 92%, SPECT/CT at 72 hours an overall pooled sensitivity of 71% and contrast enhanced standardized 3T MRI an overall pooled sensitivity of 76%.
1) These preliminary data suggest that PET/CT performs better as standardized MRI imaging and SPECT/CT at lower irradiation dose and much shorter investigation time than the latter.
2) GLP-1R PET/CT will be a useful diagnostic tool in patients in which an insulinoma is suspected.
Nothing to Disclose: KA, MF, TH, GPN, EM, JCR, BG, DW, ERC