The Added Diagnostic Value of 18F-Fluorodihydroxyphenylalanine PET/CT in the Preoperative Work-Up of Small Bowel Neuroendocrine Tumors.

BACKGROUND: The precise localization of the primary tumor and/or the identification of multiple primary tumors improves the preoperative work-up in patients with small bowel (SB) neuroendocrine tumor (NET). The present study assesses the diagnostic value of 18F-fluorodihydroxyphenylalanine (18F-FDOPA) positron emission tomography/computed tomography (PET/CT) during the preoperative wok-up of SB NETs.

METHODS: Between January 2010 and June 2017, all consecutive patients with SB NETs undergoing preoperative 18F-FDOPA PET/CT and successive resection were analyzed. Preoperative work-up included computed tomography (CT), somatostatin receptor scintigraphy (SRS), and 18F-FDOPA PET/CT. Sensitivity and accuracy ratio for primary and multiple tumor detection were compared with data from surgery and pathology.

RESULTS: There were 17 consecutive patients with SB NETs undergoing surgery. Nine patients (53%) had multiple tumors, 15 (88%) metastatic lymph nodes, 3 (18%) peritoneal carcinomatosis, and 9 patients (53%) liver metastases. A total of 70 SB NETs were found by pathology. Surgery identified the primary in 17/17 (100%) patients and recognized seven of 9 patients (78%) with multiple synchronous SB. Preoperatively, 18F-FDOPA PET/CT displayed a statistically significant higher sensitivity for primary tumor localization (100 vs. 23.5 vs. 29.5%) and multiple tumor detection (78 vs. 22 vs. 11%) over SRS and CT. Compared with pathology, 18F-FDOPA PET/CT displayed the highest accuracy ratio for number of tumor detected over CT and SRS (2.0 ± 2.2 vs. 0.4 ± 0.7 vs. 0.6 ± 1.5, p = 0.0003).

CONCLUSION: 18F-FDOPA PET/CT significantly increased the sensitivity and accuracy for primary and multiple SB NET identification. 18F-FDOPA PET/CT should be included systematically in the preoperative work-up of SB NET.