Endoscopic ultrasonography (EUS)-guided SSTR PET/CT imaging in the management of patients with small (<2 cm) gastrointestinal neuroendocrine neoplasms: A multicenter study

This study sought to investigate the necessity of somatostatin receptor (SSTR)-targeted PET/CT in patients with small (<2 cm) gastrointestinal neuroendocrine neoplasms (GI-NENs), and to explore endoscopic ultrasonography (EUS) guided SSTR-PET/CT decision-making. A total of 102 patients with suspected GI-NENs were retrospectively included from three centers in China, with a follow-up time of 19.8–82.8 months. The diagnostic efficiency of SSTR-PET/CT was analyzed. Univariate and multivariate analyses were performed to investigate factors associated with SSTR-PET efficiency. The receiver operating characteristic curve was used to determine the optimal threshold. Another 30 patients were prospectively involved to verify the feasibility of EUS-guided SSTR-PET/CT decision-making. Out of 102 patients, 90 were diagnosed with GI-NENs, leading to a sensitivity of 63.3 %, specificity of 75.0 %, and accuracy of 64.7 %. Of these, 36.7 % of primary GI-NENs showed negative SSTR-PET results. Tumor size was confirmed as the primary determinant of SSTR-PET positivity (OR = 1.87, p < 0.001), with an optimal threshold of 6.3 mm. SSTR-PET did not detect metastases in patients with primary tumors <5 mm. The optimal cutoff for predicting metastasis was 10.5 mm. At the end of the follow-up, the overall survival rate was 98.7 %, with no recurrence in patients initially negative on SSTR-PET. In patients with small (<2 cm) GI-NENs, SSTR-PET/CT imaging decision could be guided by EUS. Patients with tumors larger than 6.3 mm, particularly those with tumors exceeding 10.5 mm, could benefit from SSTR-PET imaging. However, for patients with primary tumors smaller than 6.3 mm, undergoing SSTR-PET/CT may be unnecessary.