Diffusion kurtosis imaging of gliomas grades II and III - a study of perilesional tumor infiltration, tumor grades and subtypes at clinical presentation

Abstract

BackgroundDiffusion kurtosis imaging (DKI) allows for assessment of diffusion influenced by microcellular structures. We analyzed DKI in suspected low-grade gliomas prior to histopathological diagnosis. The aim was to investigate if diffusion parameters in the perilesional normal-appearing white matter (NAWM) differed from contralesional white matter, and to investigate differences between glioma malignancy grades II and III and glioma subtypes (astrocytomas and oligodendrogliomas).Patients and methodsForty-eight patients with suspected low-grade glioma were prospectively recruited to this institutional review board-approved study and investigated with preoperative DKI at 3T after written informed consent. Patients with histologically proven glioma grades II or III were further analyzed (n=35). Regions of interest (ROIs) were delineated on T2FLAIR images and co-registered to diffusion MRI parameter maps. Mean DKI data were compared between perilesional and contralesional NAWM (student’s t-test for dependent samples, Wilcoxon matched pairs test). Histogram DKI data were compared between glioma types and glioma grades (multiple comparisons of mean ranks for all groups). The discriminating potential for DKI in assessing glioma type and grade was assessed with receiver operating characteristics (ROC) curves.ResultsThere were significant differences in all mean DKI variables between perilesional and contralesional NAWM (p=<0.000), except for axial kurtosis (p=0.099). Forty-four histogram variables differed significantly between glioma grades II (n=23) and III (n=12) (p=0.003−0.048) and 10 variables differed significantly between ACs (n=18) and ODs (n=17) (p=0.011−0.050). ROC curves of the best discriminating variables had an area under the curve (AUC) of 0.657−0.815.ConclusionsMean DKI variables in perilesional NAWM differ significantly from contralesional NAWM, suggesting altered microstructure by tumor infiltration not depicted on morphological MRI. Histogram analysis of DKI data identifies differences between glioma grades and subtypes.

Value of diffusion kurtosis imaging in assessing low‐grade gliomas

“…In addition to the solid region, the pWM also showed decreased kurtosis metrics than the surrounding white matter regions. This is consistent with the study of Delgado et al that showed significant differences in DKI metrics from the pWM as compared to cNAWM in a mixed group of 35 patients with grade II and III lesions . The result shows that tumorigenesis effects in LGGs are seen in surrounding WM regions, which has been demonstrated using histologic studies …”

“…This study showed mean, radial, and axial kurtosis metrics to be more sensitive to diffuse changes in the pWM with larger effect sizes than corresponding diffusion metrics in delineating the pWM from lesion tissue, whereas AK provided the largest increase in effect size in discriminating pWM from cNAWM. This is contrary to the finding reported by Delgado et al that showed no significant differences in AK between pWM and cNAWM . The discrepancy may be due to the heterogeneity in gliomas induced by the amalgamation of grade II and III gliomas in their study, which included 23 grades II and 12 grade III gliomas.…”

“…All kurtosis metrics showed a progressive increase in kurtosis metrics obtained from the solid lesion, pWM, and cNAWM. This finding, also observed in other studies, can be attributed to the lower cellularity accompanied by large cellular sizes resulting in a reduced extracellular space in the tumor region . The resultant structural complexity in the lesion is thus lower than that of cNAWM, resulting in increased diffusion metrics accompanied by decreased kurtosis metrics in the lesion as compared to contralateral white matter regions.…”

“…This is consistent with the study of Delgado et al that showed significant differences in DKI metrics from the pWM as compared to cNAWM in a mixed group of 35 patients with grade II and III lesions. 22 The result shows that tumorigenesis effects in…”

“…This finding, also observed in other studies, can be attributed to the lower cellularity accompanied by large cellular sizes resulting in a reduced extracellular space in the tumor region. 11,13,22 The resultant structural complexity in the lesion is thus lower than that of cNAWM, resulting in increased diffusion metrics accompanied by decreased kurtosis metrics in the lesion as compared to contralateral white matter regions. In addition to the solid region, the pWM also showed decreased kurtosis metrics than the surrounding white matter regions.…”