MRI Patterns of Extrapontine Lesion Extension in Diffuse Intrinsic Pontine Gliomas

Abstract

BACKGROUND AND PURPOSE: Diffuse intrinsic pontine glioma is a devastating childhood cancer that despite being primarily diagnosed by MR imaging alone, lacks robust prognostic imaging features. This study investigated patterns and quantification of extrapontine lesion extensions as potential prognostic imaging biomarkers for survival in children with newly diagnosed diffuse intrinsic pontine glioma. MATERIALS AND METHODS: Volumetric analysis of baseline MR imaging studies was completed in 131 patients with radiographically defined typical diffuse intrinsic pontine gliomas. Extrapontine tumor extension was classified according to the direction of extension: midbrain, medulla oblongata, and right and left middle cerebellar peduncles; various extrapontine lesion extension patterns were evaluated. The Kaplan-Meier method was used to estimate survival differences; linear regression was used to evaluate clinical-radiographic variables prognostic of survival. RESULTS: At least 1 extrapontine lesion extension was observed in 125 patients (95.4%). Of the 11 different extrapontine lesion extension patterns encountered in our cohort, 2 were statistically significant predictors of survival. Any extension into the middle cerebellar peduncles was prognostic of shorter overall survival (P 4 .01), but extension into both the midbrain and medulla oblongata but without extension into either middle cerebellar peduncle was prognostic of longer overall survival compared with those having no extension (P 4 .04) or those having any other pattern of extension (P , .001). CONCLUSIONS: Within this large cohort of patients with typical diffuse intrinsic pontine gliomas, 2 specific extrapontine lesion extension patterns were associated with a significant overall survival advantage or disadvantage. Our findings may be valuable for risk stratification and radiation therapy planning in future clinical trials. ABBREVIATIONS: DIPG 4 diffuse intrinsic pontine glioma; EPLE 4 extrapontine lesion extension; ETV 4 extrapontine tumor volume; MCP 4 middle cerebellar peduncle; OS 4 overall survival; PFS 4 progression-free survival; PTV 4 pontine tumor volume; RT 4 radiation therapy; TTV 4 total tumor volume H igh-grade gliomas comprise 10%-15% of pediatric brain tumors and cause half of the deaths occurring as a result of CNS neoplasms in children. 1,2 Of pediatric high-grade gliomas, those occurring in the pons, formerly referred to as diffuse intrinsic pontine glioma (DIPG), are most common and have the worst prognosis, with a 2-year survival rate of ,10%. 2,3

Prediction of H3K27M mutation status of diffuse midline gliomas using MRI features

“…25 On the other hand, some authors found no significantly different cMRI parameters (such as tumor location, margin, cysts, necrosis, hemorrhage, degree, and pattern of contrast enhancement and edema) that could distinguish the mutant from WT DMGs. 2,6,10,25,26 When we compared the cMRI features between thalamic mutant and WT tumors, mutant tumors showed more exophytic components.…”

Can Conventional MRI Features Predict H3K27M Mutation Status of Diffuse Midline Gliomas?

“…Castel et al have reported that the more aggressive H3.3mutant DMGs exhibited lesser extracellular edema as compared to the less aggressive H3.1 mutant DMGs [23]. On the other hand, some authors found no signi cantly different cMRI parameters (such as tumor location, margin, cysts, necrosis, hemorrhage, degree, and pattern of contrast enhancement and edema) that could distinguish the mutant from WT DMGs [2,6,10,23,24].…”

Imaging of brain tumors in children: the basics—a narrative review

“…Despite the overall poor outcome, survival differences are observed according to the anatomic distribution of these brainstem tumors and to the age of onset-neoplasms arising outside of the pons; in older children, they are apparently linked to a slightly better outcome (51). Extension of the tumor throughout the cerebellar peduncles may also be observed and it is associated with a worse outcome (52).…”

“…The tumor often has a variable T2WI signal intensity, not necessarily representing areas of liquefaction or necrosis. Areas of enhancement are often subtle, with a mild linear or punctate form (52), and may vary according to the location of these tumors; pontine gliomas tend to enhance more frequently than the thalamic ones at a rate of 67% versus 50%, respectively (55).…”