Evaluation of the diagnostic contribution of ⁶⁸Ga-DOTA-TOC PET-CT compared with somatostatin receptor single-photon scintigraphy in type 1 multiple endocrine neoplasia

Context: Somatostatin Receptor scintigraphy with ¹¹¹In-pentetreotide (SRS) is used to detect duodenopancreatic neuroendocrine tumors (dpNETs) in 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 conventional SRS but there is at present only limited data for dpNET detection in MEN1. Objective: To compare the performances of ⁶⁸Ga-DOTA-TOC PET/CT, SRS and contrast-enhanced computed tomography (CE-CT) in the diagnosis of dpNETs in MEN1. Patients and Methods: 19 consecutive MEN1 patients (aged 47 ± 13 y) underwent ⁶⁸Ga- DOTA-TOC PET/CT, SRS with SPECT/CT on abdominal region, and CE-CT within two months in random order. Blinded readings of images were performed separately by 3 experienced physicians. Unblinded analysis of CE-CT, combined with additional imaging techniques such as magnetic resonance imaging, endoscopic-ultrasound, ¹⁸F-FDG PET/CT or histopathology results served as reference standard for dpNETs diagnosis. Results: The sensitivity of ⁶⁸Ga-DOTA-TOC PET/CT and SRS was 76% and 20% respectively (p<0.0001). All 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. False negatives of ⁶⁸Ga-DOTA-TOC PET/CT included small dpNETs (< 10 mm) and ¹⁸F-FDG PET/CT positive aggressive dpNETs. In addition, whole body mapping with ⁶⁸Ga-DOTA-TOC PET/CT identified extra-abdominal MEN1-related tumors including one bronchial carcinoid undetected by CECT and 3 meningiomas undetected by SRS. Conclusion: Owing to higher diagnostic performance, ⁶⁸Ga-DOTA-TOC PET/CT should replace SRS in the investigation of MEN1 patients. (author)