NIMG-02VOLUMETRIC RELATIONSHIP BETWEEN 2-HYDROXYGLUTARATE AND FLAIR HYPERINTENSITY IN PATIENTS WITH MUTANT IDH1 GLIOMA

Abstract

BACKGROUND: The hallmark metabolic alteration of mutant IDH gliomas is the production of 2-hydroxyglutarate (2HG) [1], and high levels of this metabolite play a central role in downstream effects of gene mutation [2]. Hence, 2HG may be an ideal biomarker for both diagnosing IDH mutations and monitoring response to treatment. On the other hand tumor extension assessed by MRI FLAIR hyperintensity is the most used neuroimaging method for glioma treatment planning and monitoring. Here, we investigated the relationship between 2HG volume and FLAIR hyperintensity volume in a cohort of IDH mutant glioma patients. METHODS: Twenty-two patients with mutant IDH1 gliomas were imaged by MRI at 3T. A 3D MR spectroscopic imaging sequence [3] was employed to specifically image 2HG edited signal. FLAIR imaging was performed using standard clinical protocols. The overlap and displacement of 2HG and FLAIR volumes were calculated and compared. RESULTS: In 14 patients the 2HG volume was larger than the FLAIR volume. Across the entire cohort, the median volume of 2HG was 39.2 cc (95% CI = 11.7-83.1 cc) while the median volume of FLAIR was 25.7 cc (95% CI = 7.2-52.5 cc). The median displacement between the centers of mass of the 2HG and FLAIR volumes was 11.9 mm (95% CI = 6.2-22.2 mm). CONCLUSIONS: Our results indicate that for most patients the 2HG volumetric assessment of tumor burden is more extensive than the FLAIR volume. In addition, there is frequently an asymmetric displacement between the center of tumor volume probed by FLAIR and the center of 2HG volume. These results may have important implications for treatment planning and monitoring.