Isocitrate dehydrogenase mutation is associated with tumor location and magnetic resonance imaging characteristics in astrocytic neoplasms

Abstract

The molecular subsets of glioma behave in biologically distinct ways. The present study detected isocitrate dehydrogenase (IDH) 1 and IDH2 mutations in glioma to analyze whether IDH-mutated gliomas are situated in certain preferential areas and to investigate their correlation with magnetic resonance imaging (MRI) characteristics. A series of 193 patients with astrocytic neoplasms (111 diffuse and 82 anaplastic astrocytomas), grouped according to prelabeled anatomical structures and the risk of surgery, were retrospectively reviewed for IDH1 and IDH2 mutations to compare the tumor location and MRI features. A total of 111 IDH1 mutations at codon 132 (57.5%) and six IDH2 mutations at codon 172 (3.1%) were detected. The IDH1/2 mutations were found to predict longer survival, independent of the histological type in this series of patients. The IDH-mutated gliomas were predominantly located in a single lobe, such as the frontal lobe, temporal lobe or cerebellum and rarely in the diencephalon or brain stem. Furthermore, according to the risk of surgery, the IDH-mutated tumors were rarely located in the high-risk regions of the brain, where surgery exhibits a high mortality rate intraoperatively and postoperatively. In addition, gliomas with IDH mutations were significantly more likely to exhibit a unilateral pattern of growth, sharp tumor margins, homogeneous signal intensity and less contrast enhancement on MRI. The results of the current study suggested that the prolonged survival of patients with IDH-mutated gliomas is primarily due to a less aggressive biological behavior according to tumor site and MRI features.

Keywords: astrocytoma; isocitrate dehydrogenase; magnetic resonance imaging; prognosis; tumor location.

Figure 1

Patient with histological World Health Organization grade II diffuse astrocytoma and isocitrate dehydrogenase 1 mutation. Magnetic resonance imaging (A) T2-weighted, (B) T1-weighted, (C) FLAIR and (D) postcontrast T1-weighted axial as well as postcontrast T1-weighted (E) sagittal and (F) coronal (indicated by the black arrow) images demonstrated a lesion located in the posterior part of the superior frontal gyrus (non-functional region). The lesion (hyperintense on T2 images, hypointense on T1 images and hyperintense on FLAIR images with no postcontrast enhancement) showed well-demarcated, homogeneous high-signal intensity predominantly involving the white matter. No significant edema or mass effect were found adjacent to the cerebral falx. FLAIR, fluid-attenuated inversion recovery.

Figure 2

Patient with histological World Health Organization grade III anaplastic astrocytoma and no isocitrate dehydrogenase 1/2 mutation. Magnetic resonance imaging (A) T1-weighted (B and C) T2-weighted and (D) postcontrast T1-weighted axial as well as post-contrast T2-weighted (E) sagittal and (F) coronal images revealed an ill-defined insular mass, measuring 3.2×2.9 cm, near the anterior limb of the internal capsule (functional region). Following contrast administration, an intense, irregular enhancement was recognized and a significant mass effect was observed adjacent to the basal ganglia with evident edema.

Figure 3

Patient with histological World Health Organization grade III anaplastic astrocytoma and no isocitrate dehydrogenase 1/2 mutation. Magnetic resonance imaging (A) T2-weighted, (B) T1-weighted and (C) postcontrast T1-weighted axial as well as post-contrast T1-weighted (D) sagittal and (E and F) coronal images demonstrated an ill-defined mass severely invading the medulla oblongata (high-risk region). The lesion showed heterogeneous T2 hyperintense and T1 iso-hyperintense signals with apparent enhancement following the contrast administration and a significant mass effect was observed without edema.