MRI Evaluation of Non-Necrotic T2-Hyperintense Foci in Pediatric Diffuse Intrinsic Pontine Glioma

Abstract

Background and Purpose The conventional MRI appearance of diffuse intrinsic pontine glioma suggests intralesional histopathological heterogeneity, and various distinct lesion components, including T2-hypointense foci, have been described. Here we report the prevalence, conventional MRI semiology, and advanced MRI features of non-necrotic T2-hyperintense foci within diffuse intrinsic pontine glioma. Materials and Methods Twenty-five patients with diffuse intrinsic pontine glioma were included in this study. MRI studies were performed at 3T by using conventional and advanced MRI sequences. Perfusion (CBV), vascular permeability (ve, Ktrans) and diffusion (ADC) metrics were calculated and used to characterize non-necrotic T2-hyperintense foci in comparison with other lesion components, namely necrotic T2-hyperintense foci, T2-hypointense foci, peritumoral edema, and normal brainstem. Statistical analysis was performed by using Kruskal–Wallis and Wilcoxon rank sum tests. Results Sixteen non-necrotic T2-hyperintense foci were found in 12 tumors. In these foci, ADC values were significantly higher than those in either T2-hypointense foci (P=.002) or normal parenchyma (P=.0002), and relative CBV values were significantly lower than those in either T2-hypointense (P=.0002) or necrotic T2-hyperintense (P=.006) foci. Ktrans values in T2-hyperintense foci were lower than those in T2-hypointense (P=.0005) or necrotic T2-hyperintense (P=.0348) foci. Conclusion Non-necrotic T2-hyperintense foci are common, distinct lesion components within diffuse intrinsic pontine glioma. Advanced MR data suggest low cellularity and an early stage of angioneogenesis with leaky vessels resulting in expansion of the extracellular space. Because of the lack of biopsy validation, the underlying histoarchitectural and pathophysiological changes remain unclear; therefore, these foci may correspond to a poorly understood biological event in tumor evolution.

Quantifying radiation therapy response using apparent diffusion coefficient (ADC) parametric mapping of pediatric diffuse intrinsic pontine glioma: a report from the pediatric brain tumor consortium

“…16 These results are supported by findings by Clerk-Lamalice et al, where the authors suggest that a T2 hyperintense lesion with high ADC prior to RT is indicative of treatable vasogenic edema due to leaky angiogenic vessels, while a T2 hypointense lesion accompanied by low ADC may correspond to focal anaplasia prior to RT. 17 This is consistent with our observations comparing post-RT ADC measures.…”

Prognostic factors in adult brainstem glioma: a tertiary care center analysis and review of the literature

“…However and consistent with prior findings, lower ADC values below the median were significantly associated with shorter overall survival rates in our analysis. Previous studies in children and in adults reported the correlation between ADC values and outcome [20,21]. ADC values inversely represent tumour cellularity as the underlying biological condition [24][25][26].…”

“…Apparent diffusion coefficient (ADC) values are derived from diffusion-weighted tensor imaging (DWI). Several studies reported an inverse correlation between ADC values and tumour cellularity in gliomas, serving as an indicator of tumour cell density and proliferative potential [ 20 , 21 ]. Thus, quantitative ADC measurements may be used to discriminate between high and low-grade lesions and to predict patients’ outcome [ 22 , 23 ].…”