Prediction of<i>IDH1</i>-Mutation and 1p/19q-Codeletion Status Using Preoperative MR Imaging Phenotypes in Lower Grade Gliomas

Abstract

<h3>BACKGROUND AND PURPOSE:</h3> WHO grade II gliomas are divided into three classes: <i>isocitrate dehydrogenase (IDH)</i>-wildtype, <i>IDH</i>-mutant and no 1p/19q codeletion, and <i>IDH</i>-mutant and 1p/19q-codeleted. Different molecular subtypes have been reported to have prognostic differences and different chemosensitivity. Our aim was to evaluate the predictive value of imaging phenotypes assessed with the Visually AcceSAble Rembrandt Images lexicon for molecular classification of lower grade gliomas. <h3>MATERIALS AND METHODS:</h3> MR imaging scans of 175 patients with lower grade gliomas with known <i>IDH1</i> mutation and 1p/19q-codeletion status were included (78 grade II and 97 grade III) in the discovery set. MR imaging features were reviewed by using Visually AcceSAble Rembrandt Images (VASARI); their associations with molecular markers were assessed. The predictive power of imaging features for <i>IDH1</i>-wild type tumors was evaluated using the Least Absolute Shrinkage and Selection Operator. We tested the model in a validation set (40 subjects). <h3>RESULTS:</h3> Various imaging features were significantly different according to <i>IDH1</i> mutation. Nonlobar location, larger proportion of enhancing tumors, multifocal/multicentric distribution, and poor definition of nonenhancing margins were independent predictors of an <i>IDH1</i> wild type according to the Least Absolute Shrinkage and Selection Operator. The areas under the curve for the prediction model were 0.859 and 0.778 in the discovery and validation sets, respectively. The <i>IDH1</i>-mutant, 1p/19q-codeleted group frequently had mixed/restricted diffusion characteristics and showed more pial invasion compared with the <i>IDH1</i>-mutant, no codeletion group. <h3>CONCLUSIONS:</h3> Preoperative MR imaging phenotypes are different according to the molecular markers of lower grade gliomas, and they may be helpful in predicting the <i>IDH1-</i>mutation status.