Objectives: Assess the feasibility of imaging brain lesions with ⁶⁸Ga-PSMA PET/CT and its comparison with ¹⁸F-FDG PET/CT.

Methods:  Ten patients with brain lesions referred for ¹⁸F-FDG PET/CT scan were included in the study. Six patients were treated cases of glioblastoma with suspected recurrence on recent follow up magnetic resonance imaging. Five patients showed scan evidence of disease recurrence in ¹⁸F-FDG and ⁶⁸Ga-PSMA Brain PET/CT imaging. They underwent surgery and histopathology confirmed disease recurrence. One patient showed no evidence of disease in both the scans and was kept on clinical/imaging follow up. The remaining four patients were sent for assessing the nature (primary lesion /metastasis) of space occupying lesion in brain. They underwent whole body ¹⁸F-FDG PET/CT scan and a primary site elsewhere in the body was ruled out. Subsequently they underwent ⁶⁸Ga-PSMA PET/CT brain imaging prior to surgery/biospy. Target to background ratios (TBR) for the brain lesions were calculated using contralateral brain parenchyma and cerebellar uptakes separately as background.

Results: In six treated cases of glioblastoma with suspected recurrence the findings of ⁶⁸Ga-PSMA PET/CT showed excellent correlation with that of ¹⁸F-FDG PET/CT scan. Compared to the ¹⁸F-FDG PET/CT, ⁶⁸Ga-PSMA PET/CT showed excellent visualization of the recurrent lesion (presence/absence) owing to its significantly high TBR. In remaining four cases histopathology confirmed them to be lymphoma, atypical meningioma, glioblastoma and tubercular granuloma with distinct uptake pattern in both the scans.

Conclusion: ⁶⁸Ga-PSMA PET/CT brain imaging is a potentially useful imaging tool in the evaluation of brain lesions. In ⁶⁸Ga-PSMA PET/CT absence of physiological tracer uptake in the normal brain parenchyma offers significantly high TBR in comparison with ¹⁸F-FDG PET/CT, thus resulting in better visualization of metabolically active disease in the brain.