NIMG-15. 2-HYDROXYGLUTARATE MAGNETIC RESONANCE SPECTROSCOPY IN ADULT BRAINSTEM GLIOMA PATIENTS

Abstract

Abstract OBJECTIVE The onco-metabolite, 2-Hydroxyglutarate (2HG), is non-invasive biomarker for detecting isocitrate dehydrogenase (IDH) mutant glioma by MR-Spectroscopy. Especially 2HG-MRS may be useful in patients with brainstem lesions, where surgical biopsy presents high risk of neurological injury. Here, we examined the utility of 2HG-MRS for diagnosis of IDH mutant adult brainstem glioma. METHODS We conducted 3 tesla -MRS (3T-MRS) in 8 radiographically identified brainstem tumor (7 male and 1 female, median age 39). Single-voxel was localized from the T2-FLAIR using a 2HG-tailored MRS protocol (Philips, Achieva, PRESS, TE 35 ms). All patients underwent tumor biopsy using an intraoperative navigation system (Brain LABTM) or stereotactic biopsy system (Komai’s CT-stereotactic frame) before initial treatment. IDH and H3K27M status were diagnosed by IHC and DNA sequence. RESULTS 3 cases were H3K27M and 4 cases were IDH mutant (R132H 1 case, R132S 2 cases, and R132G 1 case). 1 case were neither H3K27M nor IDH mutant. H3-K27 and IDH1 mutations were mutually exclusive. All tumor located at pons. There were no significant radiological difference between H3K27M and IDH mutant in conventional MRI sequence. Pearson's chi-square test demonstrated that 2HG concentrations >1.5 mM were 100% sensitive and 75% specific for IDH mutant glioma (p = 0.0285). The median overall survival survival were 127 month in IDH mutant glioma (n=4) and 22.5 months in IDH wild-type glioma (n=4), respectively. CONCLUSIONS 2HG in adult brainstem glioma was detected by conventional 3T-MRS successfully. A noninvasive 2HG-MRS may be useful diagnostic modality for evaluating molecular status and prognosis in brainstem glioma noninvasively.