68Ga-Prostate-Specific Membrane Antigen-11 PET/CT: A New Imaging Option for Recurrent Glioblastoma Multiforme?

Background: Glioblastoma multiforme (GBM) is the most common and most aggressive primary tumor of the brain. After initial therapy and total resection of GBM, 80% to 90% of recurrences occur at the surgical margins. Currently, limited data are available in the literature on the possible use of Ga-prostate-specific membrane antigen (PSMA-11) for diagnosis of recurrence in GBM patients. The aim was to assess the feasibility and potential of Ga-PSMA-11 PET/CT as a diagnostic procedure in patients with histologically confirmed of GBM and suspected recurrent disease on MRI.

Results: No radiopharmaceutical-related adverse events were noted. Characterization of recurrent disease with MRI included T2-weighted fast spin-echo images, fluid-attenuated inversion recovery and diffusion-weighted imaging sequences, and gadolinium enhanced T1-weighted images. Visual interpretation of PET showed increased accumulation of Ga-PSMA-11 in recurrent lesion detected by T1 contrast enhanced and diffusion-weighted imaging images in all patients with a median SUVmax of the tumor of 6.5 and an SUVmean of 3.5. The median tumor-to-background brain ratio and tumor-to-liver ratio obtained from Ga-PSMA-11 PET/CT were 96.7 and 0.8, respectively.

Conclusions: The extremely low background uptake in normal brain tissue and consequently high tumor-to-brain ratio make Ga-PSMA-11 PET/CT highly promising for diagnosis of recurrent disease in GBM patients. Although PSMA expression in recurrent GBM also opens a potential way for targeted peptide therapy with α/β-emitters as well as for prediction of treatment with antiangiogenic agents, the low tumor-to-liver ratio observed in the majority of patients in this study suggests a limited role of radiolabeled PSMA ligands for targeted radionuclide therapy of recurrent GBM.