<sup>11</sup>C-methionine PET-CT in the diagnosis of anaplastic astrocytomas and anaplastic oligodendrogliomas

Abstract

The aim of this study was to evaluate average 11C-methionine uptake for grade II (anaplastic) gliomas in a large cohort, as well as relations between MRI and PET characteristics and their unfluence on overall and progression-free survival.Materials and methods. The study was based upon 78 patients with supratentorial tumors, among them 48 with anaplastic astrocytoma (AA) and 30 with anaplastic oligodendroglioma (AO). ALL patients underwent PET-CT with 11C-methionine and MRI study (Т1, Т2, Т2-FLAIR, DWI и 3D Т1+Gd regimes). Tumor removal was performed in 71 cases, stereotactic biopsy in 8 patients. Tumor specimen were assessed by neuropatomorphologists and IDH1-status and 1p/19q co-deletion were evaluated.Study results. AA IDH− tumors demonstrated statistically significant bigger metabolic volume and radiotracer uptake comparing with AA IDH+. Moreover, AA IDH − characterized by higher fractional MET uptake. The smallest tumors (by MRI) were AOs, meanwhile their fractional contrast enhancement was higher than for AAs. AOs were also known as tumors with minimal difference between MRI and PET-CT volume. MET uptake decreased in a row АА IDH− – АОД – AA IDH+, but the difference has not reached statistical significance. For wild-type AAs metabolic volume correlated with OS and PFS, meanwhile for IDH-mutant AAs tumor volume (measured by MRI) correlated only with PFS.Conclusion. Present study based on the largest cohort of patients with anaplastic gliomas who underwent both MRI and PET with 11C-methionine. It turned out, that unlike grade II oligodendogliomas, AOs do not always demonstrate higher than their astrocytic counterparts MET uptake levels.