Radiological characteristics based on isocitrate dehydrogenase mutations and 1p/19q codeletion in grade II and III gliomas

The radiological features of lower-grade gliomas (LGGs) classified according to isocitrate dehydrogenase (IDH) mutations and codeletion of chromosomal arms 1p and 19q (1p/19q codeletion) remain unclear. We aimed to systematically characterize the radiological features of molecularly classified LGGs using IDH and 1p/19q codeletion statuses. One hundred and one LGGs were re-classified into 36 tumors with IDH mutations (IDH-Mut), 35 tumors with IDH-Mut and 1p/19q codeletion (IDH-Mut/Codel), and 30 tumors with wildtype IDH (IDH-Wt). Calcification, heterogeneous signal intensity in T2-weighted images, and cortical invasion were significantly more frequent in IDH-Mut/Codel than in IDH-Mut and IDH-Wt tumors (calcification: 48.6 vs 5.6 and 6.7%, heterogeneity: 94.3 vs 33.3 and 50%, and cortical invasion: 94.3 vs 55.6 and 40.0%, respectively). A frontal location was significantly more frequent for IDH-Mut and IDH-Mut/Codel than for IDH-Wt tumors (52.8 and 71.4 vs 12.1%, respectively), and dense contrast-enhancement was significantly more frequent in IDH-Wt than in IDH-Mut and IDH-Mut/Codel tumors (50.0 vs 2.8 and 2.9%, respectively). In conclusion, IDH-Mut/Codel tumors were characterized by calcification, frontal location, heterogeneous signal intensity, and cortical invasion; IDH-Mut tumors differed from IDH-Wt tumors according to predominant frontal lobe location and less frequent dense enhancement patterns.