Context
Somatostatin receptor scintigraphy with 111In-pentetreotide (SRS) is used to detect duodenopancreatic neuroendocrine tumors (dpNETs) in multiple endocrine neoplasia type 1 (MEN1). However, SRS has limited sensitivity for this purpose. Positron emission tomography/computed tomography (PET/CT) with 68Ga-DOTA-TOC has a higher rate of sporadic dpNETs detection than SRS but there is little data for dpNETs detection in MEN1.
Purpose
To compare the performances of 68Ga-DOTA-TOC PET/CT, SRS and contrast-enhanced computed tomography (CE-CT) to diagnose dpNETs in MEN1.
Design and setting
Single-institution prospective comparative study
Patients and methods
Nineteen consecutive MEN1 patients (aged 47 ± 13 years) underwent 68Ga-DOTA-TOC PET/CT, SRS, and CE-CT within 2 months in random order. Blinded readings of images were performed separately by experienced physicians. Unblinded analysis of CE-CT, combined with additional magnetic resonance imaging, endoscopic-ultrasound, 18F-2-fluoro-deoxy-d-glucose (18F-FDG) PET/CT or histopathology results served as reference standard for dpNETs diagnosis.
Results
The sensitivity of 68Ga-DOTA-TOC PET/CT, SRS, and CE-CT was 76, 20, and 60 %, respectively (p < 0.0001). All the true-positive lesions detected by SRS were also depicted on 68Ga-DOTA-TOC PET/CT. 68Ga-DOTA-TOC PET/CT detected lesions of smaller size than SRS (10.7 ± 7.6 and 15.2 ± 5.9 mm, respectively, p < 0.03). False negatives of 68Ga-DOTA-TOC PET/CT included small dpNETs (<10 mm) and 18F-FDG PET/CT positive aggressive dpNETs. No false positives were recorded. In addition, whole-body mapping with 68Ga-DOTA-TOC PET/CT identified extra-abdominal MEN1-related tumors including one neuroendocrine thymic carcinoma identified by the three imaging procedures, one bronchial carcinoid undetected by CE-CT and three meningiomas undetected by SRS.
Conclusions
Owing to higher diagnostic performance, 68Ga-DOTA-TOC PET/CT (or alternative 68Ga-labeled somatostatin analogues) should replace 111In-pentetreotide in the investigation of MEN1 patients.