IDH1 mutation is associated with low FDG upatke in cerebral gliomas associated with low FDG uptake in cerebral gliomas.

Objectives: IDH1 mutations occur in up to 12% of all GBMs and 70% of low-grade gliomas and secondary glioblastomas(1-2). A few studies reported low glucose transporter expression in IDH1 mutant tumors(3-4). This study was to evaluate the correlation between F-18 FDG uptake on positron emission tomography/computed tomography (PET/CT) and IDH1 mutation in patients with cerebral gliomas.

Methods: This retrospective analysis included 48 patients (28 males, 20 females; age, 34-72 years; median age, 53.5 years) with gliomas. The tumors were histologically graded by the World Health Organization grading system. On PET/CT, the maximal standardized uptake value (SUV) ratios of the gliomas compared to contralateral cortex (G/C ratio) were measured to correlate with the presence of IDH1 mutation.

Results: There were 16 gliomas with IDH1 mutation (grade II=7, grade III=8, grade IV=1) when 32 gliomas had wild-type IDH1 ((grade II=0, grade III=8, grade IV=24). In IDH1-mutated tumors, the median G/C ratio was 0.72 which significantly low compared to 1.14 in wild type IDH1 tumors (P = 0.0029). The area under the curve of G/C ratio in predicting IDH1 mutation was 0.824 (CI: 0.689-0.919, P<0.0001). When the G/C ratio cutoff value of >1.004 was applied, only one (5%) of the 20 gliomas with a G/C ratio of >1.004 were found to be IDH1 mutant glioma whereas 15 (53.6%) of the 28 gliomas with a G/C ratio of &#8804;1.004 were found to be IDH1 mutant glioma.

Conclusion: FDG uptake on PET/CT in the cerebral gliomas was significantly low with the presence of IDH1 mutation. It seems to be an effective imaging surrogate to predict the status of IDH1 mutation in vivo. It may be of clinical relevance in selecting those patients who can benefit from IDH1 mutant directed target therapy or the usage of temozolomide. Research Support: This study was approved by the Institutional Review Board at Yonsei University College of Medicine.