Quantitative diffusion-weighted and dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging analysis of T2 hypointense lesion components in pediatric diffuse intrinsic pontine glioma

Abstract

BACKGROUND AND PURPOSE: Focal anaplasia characterized by T2 hypointensity, signal-intensity enhancement on postcontrast T1-weighted MR imaging and restricted water diffusion has been reported in a patient with juvenile pilocytic astrocytoma. We identified T2HOF with these MR imaging characteristics in children with DIPG and hypothesized that these represent areas of focal anaplasia; and may, therefore, have increased perfusion properties and should be characterized by increased perfusion. Thus, we used DSC to investigate our hypothesis. MATERIALS AND METHODS: We retrospectively reviewed the baseline MR imaging scans of 86 patients (49 girls, 37 boys; median age, 6.1 years; range, 1.1-17.6 years) treated for DIPG at our hospital (2004-2009). T2HOF with the described MR imaging characteristics was identified in 10 patients. We used a region of interest-based approach to compare the ADC, FA, rCBV, rCBF, and rMTT of T2HOF with those of the typical T2HRT. RESULTS: The ADC of T2HOF with the specified MR imaging characteristics was significantly lower than that of T2HRT (range, 0.71-1.95 μm 2/ms versus 1.36-2.13 μm2/ms; P < .01); and the FA (range, 0.12-0.34 versus 0.07-0.24; P = .03) and rCBV (range, 0.4-2.62 versus 0.23-1.57; P = .01) values of T2HOFs were significantly higher. CONCLUSIONS: Our data suggest that T2HOF in DIPG may represent areas of focal anaplasia and underline the importance of regional, rather than global, tumor-field analysis. T2HOF may be the ideal target when stereotactic biopsy of tumors that present with an inhomogeneous T2 signal intensity is considered.