68Ga PSMA PET/MR in the differentiation of low and high grade gliomas: Is 68Ga PSMA PET/MRI useful to detect brain gliomas?

Background: Magnetic resonance imaging (MRI) is the most important imaging modality in the diagnosis and follow-up of glial brain tumors. Objective: The aim of our study is to determine the correlation between tumor grade, determined with postoperative pathological examination, and standard uptake value (SUV), a semi-quantitative parameter, in patients who underwent imaging Ga-68-PSMA with using PET/MR. Material-method: Thirty-five out of 38 patients' images whose pathology was consistent with glial tumor, 42 lesions from separate anatomic localizations or with higher activity uptake than the rest of the tumor were evaluated. SUV values measured on PET images and grade relationship were evaluated based on each lesion while mitosis, Ki-67 were evaluated for each patient. Results: Grade, Ki-67, mitosis, necrosis and SUVmax/mean/peak were found statistically significant with moderate/high correlation. The parameter with the highest correlation coefficient was mitosis. (For SUVmax r = 0.64, p = 0). When Grade II and III were considered as the first group and IV as the second group, the cutoff values were found to be 2.3 for SUVmax, 0.21 for SUVmean and 0.63 for SUVpeak. In the diagnosis of HGG, PET's sensitivity is higher than MRI but no statistically difference was found between specificities. Conclusion: Ga-68 PSMA PET imaging is found to be particularly useful in differentiating Grade IV glial tumors from other grades. This finding is thought to be important in the differentiation the relapse with postoperative tissue changes, which is an important problem in the follow-up.