18F-FDOPA PET/MRI fusion in patients with primary/recurrent gliomas: Initial experience

Abstract

Background and purpose 18F-FDOPA PET demonstrates higher sensitivity and specificity for gliomas than traditional [ 18F] FDG PET imaging. However, PET provides limited anatomic localization. The purpose of this study was to determine whether 18F-FDOPA PET/MRI fusion can provide precise anatomic localization of abnormal tracer uptake and how this activity corresponds to MR signal abnormality. Methods Two groups of patients were analyzed. Group I consisted of 21 patients who underwent 18F-FDOPA PET and MRI followed by craniotomy for tumor resection. Group II consisted of 70 patients with a pathological diagnosis of glioma that had 18F-FDOPA PET and MRI but lacked additional pathologic follow-up. Fused 18F-FDOPA PET and MRI images were analyzed for concordance and correlated with histopathologic data. Results Fusion technology facilitated precise anatomical localization of 18F-FDOPA activity. In group I, all 21 cases showed pathology-confirmed tumor. Of these, 18F-FDOPA scans were positive in 9/10 (90%) previously unresected tumors, and 11/11 (100%) of recurrent tumors. Of the 70 patients in group II, concordance between MRI and 18F-FDOPA was found in 49/54 (90.1%) of patients with sufficient follow-up; in the remaining 16 patients concordance could not be determined due to lack of follow-up. 18F-FDOPA labeling was comparable in both high- and low-grade gliomas and identified both enhancing and non-enhancing tumor equally well. In some cases, 18F-FDOPA activity preceded tumor detection on MRI. Conclusion 18F-FDOPA PET/MRI fusion provides precise anatomic localization of tracer uptake and labels enhancing and non-enhancing tumor well. In a small minority of cases, 18F-FDOPA activity may identify tumor not visible on MRI.