Diagnostic Value of Ga-68 PSMA-11 PET/CT Imaging of Brain Tumors-Preliminary Analysis

Objective: To evaluate the feasibility of using Ga-68 PSMA-11 PET/CT for imaging brain lesions and its comparison with F-18-FDG. Methods: Ten patients with brain lesions were included in the study. Five patients were treated cases of glioblastoma with suspected recurrence. F-18-FDG and Ga-68 PSMA-11 brain scans were done for these patients. Five patients were sent for assessing the nature (primary lesion/metastasis) of space occupying lesion in brain. They underwent whole body F-18-FDG PET/CT scan and a primary site elsewhere in the body was ruled out. Subsequently they underwent Ga-68 PSMA-11 brain PET/CT imaging. Target to background ratios (TBR) for the brain lesions were calculated using contralateral cerebellar uptake as background. Results: In five treated cases of glioblastoma with suspected recurrence the findings of Ga-68 PSMA-11 PET/CT showed good correlation with that of F-18-FDG PET/CT scan. Compared to the F-18-FDG, Ga-68 PSMA-11 PET/CT showed better visualization of the recurrent lesion (presence/absence) owing to its significantly high TBR. Among the five cases evaluated for lesion characterization glioma and atypical meningioma patients showed higher SUVmax in the lesion with Ga-68 PSMA-11 than with F-18-FDG and converse in cases of lymphoma. TBR was better with Ga-68 PSMA PET/CT in all cases. Conclusion: Ga-68 PSMA-11 PET/CT brain imaging is a potentially useful imaging tool in the evaluation of brain lesions. Absence of physiological uptake of Ga-68 PSMA-11 in the normal brain parenchyma results in high TBR values and consequently better visualization of metabolically active disease in brain.