Evaluating the functional status of somatostatin receptors by 99mTc-octreotide scan in patients suffering from primary brain tumors.

OBJECTIVE

This study aimed to determine the functional expression of somatostatin receptors in patients with primary brain tumors including meningiomas and gliomas using 99mTc-HYNIC-octreotide SPECT/CT imaging.

METHOD: This cross-sectional study was conducted at Ghaem Hospital, Mashhad, in 2023. Patients with histopathologically confirmed primary brain tumors (gliomas and meningiomas) who had previously received treatment and presented with suspected tumor recurrence based on imaging findings were included. After injection of 99mTc-HYNIC-Octreotide, whole-body SPECT/CT imaging of the head and other suspicious areas was performed. Two nuclear medicine specialists independently reviewed scans. Radiopharmaceutical uptake was assessed qualitatively by comparing absorption in lesions to liver and splenic uptake, with scoring based on the Krenning score. The uptake in lesions (target) and their corresponding mirrored normal brain regions (non-target) was calculated using ROI measurements.

RESULTS

Out of 24 patients, scans from 18 (mean age: 51.39±12.25 years; range: 35-74) were analyzed due to technical issues and missing images. Of these, 10 (55.6%) were women. Somatostatin receptor expression was observed in all lesions. Meningioma had significantly higher receptor expression compared to gliomas (P=.003). Maximum and target-to-non-target uptake differences were significantly greater in meningioma than in astrocytoma (P=.047, P=.044) and glioblastomas (P=.025, P=.026). Gliomas, including astrocytoma and glioblastomas, consistently showed low receptor expression, and no significant differences in receptor expression were observed between astrocytoma and glioblastomas.

CONCLUSION

This study demonstrates that 99mTc-HYNIC-octreotide SPECT/CT imaging is an effective method for detecting somatostatin receptor expression in brain tumors, offering a low-cost and accessible alternative to more enhanced imaging techniques, both meningioma and glial tumors express somatostatin receptors, but receptor expression is significantly higher in meningioma.