Endocrine Abstracts

Background: Somatostatin receptor (SSTR) PET imaging is utilized with increasing frequency in the clinical management of neuroendocrine tumors. Incidental PET-avid CNS lesions are commonly noted and presumed to be meningiomas. However, SSTR PET lacks specificity for meningioma identification. This study aims to clarify the role of SSTR-based imaging for classification of incidental CNS lesions

Methods: Patients who had undergone both Ga-68-DOTATATE PET and brain MR imaging and had an incidental CNS lesion identified with a radiographic prediction of meningioma via one (discordant prediction) or both (concordant prediction) imaging modalities were retrospectively analyzed. Imaging indication, semi-quantitative measures, and corresponding clinical history were recorded.

Results: Among 48 patients with a CNS lesion identified on both imaging modalities, most scans were performed for a history of neuroendocrine tumor (64.6%). Cases with concordant lesion type prediction of meningioma between imaging modalities (N=24) displayed a significantly higher SUV max (median 7.9 vs. 4.0, P=0.008) and Krenning score (median 3.0 vs. 2.0, P=0.005) on Ga-68-DOTATATE PET compared to cases with a discordant prediction of meningioma (n=24). In cases with lower SUV max values Ga-68-DOTATATE was more likely to discordantly predict meningioma without agreement by the corresponding MRI. Prior cranial radiation or use of a somatostatin mimetic did not affect quantitative radiographic measures, and MRI-based tumor size was similar across groups.

Conclusions: Lesions with increased avidity may be more confidently predicted as meningioma in Ga-68-DOTATATE PET scans, and caution should be exercised in lesion type prediction among low SUV cases. The continued development of SSTR-based imaging biomarker signatures across incidental CNS lesion subtypes will further define the role of this imaging modality in the clinical diagnosis and management of presumed meningiomas.

Abstract ID 21355