Comparison of 18F-OC PET/CT, 18F-FDG PET/CT and CT/MRI in the detection and evaluation of neuroendocrine neoplasms

Objectives Gallium-68 (68Ga)-labeled somatostatin analog (SSA) PET imaging has been widely used in clinical practice. Compared with 68Ga, 18F has a great practical and economic advantage. The characteristics of 18F-AlF-NOTA-octreotide (18F-OC) have been even more rarely described. Herein, this retrospective study aimed to evaluate the efficacy of 18F-OC PET/CT in detecting NENs, as well as to compare it with 18F-FDG PET/CT and CT/MRI. Methods We retrospectively evaluated the data of 93 patients who had undergone 18F-OC PET/CT scans. Moreover, of 45 patients with suspected NENs, 42 patients underwent enhanced CT scans, 38 patients underwent MRI scans, and 5 patients underwent 18F-FDG PET/CT imaging. Of 48 NENs patients for detecting metastasis or recurrence, these patients had enhanced CT (n = 36), MRI (n = 30) and 18F-FDG PET/CT scans (n = 14). A total of 276 suspected NENs lesions were found in these 93 patients. Histopathologic (n = 198) or radiographic follow-up (n = 78) served as the reference standard for the final diagnosis. Results Forty-five patients with suspected NENs were confirmed by histopathological examination via resection or biopsy. 18F-OC PET/CT showed high radiotracer uptake in the lesions of G1-G3 NENs. 18F-OC PET/CT showed superior performance, with 96.3% sensitivity, 77.8% specificity and 88.9% accuracy in diagnosing NENs compared to CT/MRI. When a standardized uptake value (SUVmax) of 8.3, target-to-background ratio (TBR) of 3.1 and SUVmax of hypophysis (SUVhypophysis) of 15.4 were cutoff points for differentiating NENs from non-NENs lesions, 18F-OC PET/CT had the best equilibrium between sensitivity and specificity. For a total of 276 suspected NENs lesions, the sensitivity, specificity, and accuracy of 18F-OC were 90.5%, 82.1% and 88.8%, respectively, in the diagnosis of NENs and were higher than those of 18F-FDG PET/CT and CT/MRI. Furthermore, the TBR of 18F-OC PET was higher than that of 18F-FDG PET (P = 0.0118), especially in pancreas (P = 0.0024), liver (P max and TBR of 18F-OC PET/CT showed a significant correlation with the degree of CT enhancement in G2 but not in G1 or G3. Moreover, there was a higher blood supply and lower 18F-OC TBR in G1 and G2 NENs than in G3. Conclusions 18F-OC PET/CT is a promising imaging modality for initial diagnosis and detecting metastasis or postoperative recurrence in NENs.