Clinical usefulness of Somatostatin Receptor Scintigraphy in the Diagnosis of Neuroendocrine Neoplasms

Objective(s): We investigated the detectability of somatostatin receptor scintigraphy (SRS) for neuroendocrine neoplasms (NEN). Methods: From January 2016 to October 2020, 125 SRS examinations using indium-111 pentetreotide performed for patients with NEN lesions were retrospectively evaluated. The detection rate of NEN lesions was determined according to histopathological classification by primary site and by organ. Results: At least one NEN lesion was detected in 73% (91/125) with a positive Krenning score of ≥2 in SRS. The detection of abdominal NENs (gastrointestinal tract, 38; pancreas, 62; and others, 14) was 89% (49/55) for neuroendocrine tumor (NET)-grade (G) 1, 78% (32/41) for NET-G2, 66% (2/3) for NET-G3, 31% (4/13) for neuroendocrine carcinoma (NEC), 100% (1/1) for mixed neuroendocrine–non-neuroendocrine neoplasm, and 0% (0/1) for non-classified NEN. That of thoracic NENs was 33% (2/6) for typical carcinoid tumor and 40% (2/5) for atypical carcinoid tumor. For a total of 226 organ lesions, hepatic lesions were 76% (58/76); pancreatic lesions, 61% (31/51); lymph node lesions, 77% (27/35); bone lesions, 83% (20/24); duodenal lesions, 82% (9/11); and other lesions, 41% (11/27). Conclusion: The detectability of SRS for NEN in Japan was verified at a center, and its usefulness was confirmed.