Arterial Spin Labeling for Glioma Grade Discrimination: Correlations with IDH1 Genotype and 1p/19q Status

Abstract

Since accurate grading of gliomas has important clinical value, the aim of this study is to evaluate the diagnostic efficacy of perfusion values derived from arterial spin labeling (ASL) to grade gliomas. In addition, the correlation between perfusion and isocitrate dehydrogenase 1 (IDH1) genotypes and chromosome arms 1p and 19q (1p/19q) status of gliomas was assessed. A total of 52 cases of supratentorial gliomas in adults who received ASL imaging were enrolled in this retrospective study. The cerebral blood flow (CBF) images derived from ASL and anatomical maps were normalized to the Montreal Neurological Institute coordinate system and matched. The mean CBF (meanCBF), the maximum CBF (maxCBF), and their relative values (rmeanCBF and rmaxCBF, respectively) were assessed in each case. The tumor grades, IDH1 genotypes, and 1p/19q status were diagnosed according to the 2016 WHO criteria. Receiver operating characteristic curves were performed to assess the efficacy of perfusion parameters for grading. Qualitatively, all gliomas were divided into high- and low-perfusion groups. The crosstabs chi-square test of independence was performed to calculate contingency coefficient (C) and Cramer V coefficient to assess the correlation between perfusion and IDH1 genotypes and 1p/19q status of gliomas. The rmaxCBF showed the best diagnostic efficacy; meanwhile, rmeanCBF had the best specificity for grade discrimination. In astrocytoma, there was a mild correlation between IDH1 genotypes and tumor perfusion with the Cramer's V coefficient of 0.378. There was no significant association between 1p/19q codeletion and perfusion in grade II and III gliomas.

Figure 1

MR images in the MNI coordinate system of a 54-year-old female with diffuse astrocytoma, WHO grade II. T2-weighted FLAIR images (a), in the sagittal, coronal, and axial plane from left to right, show a hyperintense mass covered with a red translucent layer representing a 3D ROI of the whole tumor. The corresponding color-coded CBF maps (b) show lower perfusion of the tumor than the contralateral area since blue represents relatively low perfusion while red represents hyperperfusion.

Figure 2

ROC curve for meanCBF, maxCBF, rmeanCBF, and rmaxCBF in distinguishing high- from low-grade gliomas. ROC curve: receiver operating characteristic curve; meanCBF: mean CBF (ml/min/100 g); maxCBF: maximum CBF (ml/min/100 g); rmeanCBF: relative value of meanCBF (dimensionless); rmaxCBF: relative value of maxCBF (dimensionless).

Figure 3

Representative cases for WHO grade II (a, b, c), III (d, e, f), and IV (g, h, i) gliomas with aligned T2FLAIR (a, d, g), ceT1WI (b, e, h), and corresponding CBF maps (c, f, i). A 31-year-old female with diffuse astrocytoma (a, b, c). T2FLAIR (a) shows a mildly high intense mass with obscure boundary; meanwhile, ceT1WI (b) shows no obvious enhancement. The corresponding CBF map (c) show hypoperfusion of the tumor. A 50-year-old female with anaplastic oligodendroglioma (d, e, f). The tumor shows hyperintensity on T2FLAIR (d), foci of enhancement on ceT1WI (e), and heterogeneous hyperperfusion on CBF map (f). A 34-year-old male with glioblastoma (g, h, i). The tumor shows heterogeneous hyperintensity on T2FLAIR (g), obvious enhancement on ceT1WI (h), and hyperperfusion almost in all tumor zones on CBF map (f).

Figure 4

MR images and the 3D tumor mask of a 47-year-old female with IDH1–wild-type glioblastoma. The color-coded CBF maps (a) in the sagittal, coronal, and axial plane from left to right show a thick and irregular ring hyperperfusion of the tumor covered with a translucent layer representing the 3D ROI. The 3D tumor mask extracted from CBF maps is exactly projected on to the corresponding T2FLAIR (b) and ceT1WI (c).

Figure 5

A 46-year-old male with IDH1-mutant glioblastoma. T2FLAIR (a) shows a heterogeneous hyperintensity mass, with inner linear higher intensity and central hypointensity representing necrosis. CeT1WI (b) shows irregular ring enhancement with a shaggy inner margin in the same part as linear higher intensity on T2FLAIR. The corresponding CBF map (c) shows no obvious hyperperfusion in the tumor location except for the zone near the midline of brain.