Comparison of [¹⁸F]-OC PET/CT and contrast-enhanced CT/MRI in the detection and evaluation of neuroendocrine neoplasms.

Abstract

Gallium-68 (⁶⁸Ga)-labeled somatostatin analog (SSA) PET imaging has been widely used in clinical practice of neuroendocrine neoplasms (NENs). Compared with ⁶⁸Ga, ¹⁸F has a great practical and economic advantage. Although a few studies have shown the characteristics of [¹⁸F] AlF-NOTA-octreotide ([¹⁸F]-OC) in healthy volunteers and small NEN patient groups, its clinical value needs further investigation. Herein, this retrospective study aimed to evaluate the diagnostic accuracy of [¹⁸F]-OC PET/CT in detecting NENs, as well as to compare it with contrast-enhanced CT/MRI. We retrospectively reviewed the data of 93 patients who had undergone [¹⁸F]-OC PET/CT and CT or MRI scans. Of these patients, there were 45 patients with suspected NENs for diagnostic evaluation, and 48 patients with pathologically confirmed NENs for detecting metastasis or recurrence. [¹⁸F]-OC PET/CT images were evaluated visually and semi-quantitatively by measuring maximum standardized uptake value of tumor (SUV_max), tumor-to-background SUV_max ratio (TBR), and SUV_max of hypophysis (SUV_hypophysis). A total of 276 suspected NEN lesions were found in these 93 patients. The results of histopathology or radiographic follow-up served as the reference standard for the final diagnosis. 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% of sensitivity, 77.8% of specificity, and 88.9% of accuracy in diagnosing NENs compared to CT/MRI. When cutoffs of SUV_max, TBR, and SUV_hypophysis were 8.3, 3.1, and 15.4, [¹⁸F]-OC PET/CT had the best equilibrium between sensitivity and specificity for differentiating NEN from non-NEN lesions. For a total of 276 suspected NEN lesions, the sensitivity, specificity, and accuracy of [¹⁸F]-OC PET/CT for diagnosis of NENs were 90.5%, 82.1%, and 88.8%, respectively, and were higher than those of CT and MRI. G1 and G2 NENs had higher TBR and lower CT enhancement intensity than G3. The SUV_max and TBR had a positive correlation with CT enhancement intensity in G2 rather than in G1 or G3. [¹⁸F]-OC PET/CT is a promising imaging modality for initial diagnosis and detecting metastasis or postoperative recurrence in NENs.