Neuroimaging in Pediatric Brain Tumors: Gd-DTPA–enhanced, Hemodynamic, and Diffusion MR Imaging Compared with MR Spectroscopic Imaging

Abstract

BACKGROUND AND PURPOSE: Gadolinium-enhanced MR images assist in defining tumor borders; however, the relation between tumor cell extent and contrast-enhanced regions is unclear. Our aim was to improve conventional neuroimaging of pediatric brain tumors with hemodynamic, diffusion, and spectroscopic MR imaging.

METHODS: We performed conventional MR and MR spectroscopic imaging in 31 children with neuroglial brain tumors. Hemodynamic MR imaging was performed in 16 patients with a first-pass intravenous bolus of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA); apparent diffusion coefficients (ADCs) were measured in 12 patients. To account for multiple measurements in a patient, we used a nested analysis of variance.

RESULTS: At MR spectroscopy, choline (Cho)-containing compounds (indicating tumor) and lipid levels (indicating necrosis) did not correlate with percent Gd-DTPA enhancement on MR images. Percent enhancement was positively correlated with relative cerebral blood volumes (rCBVs) (P = .05) and negatively correlated with ADCs (P < .001). Stepwise multiple linear regression revealed that rCBV (P = .008), ADC (P = .022), and lipid (P < .001) levels were significant independent predictors of percent enhancement. Tumor spectral patterns were detected in tumor regions and outside enhancing tumor beds in patients with clinical progression; these were confirmed at neuropathologic analysis.

CONCLUSION: MR spectroscopic imaging improves the assessment of pediatric brain tumors by adding biochemical information regarding tumor involvement and by depicting residual or recurrent tumor outside the Gd-DTPA–enhanced tumor bed. rCBV and ADC mapping complemented MR spectroscopic imaging. We recommend the use of MR spectroscopic imaging in addition to conventional MR imaging in assessing pediatric brain tumors.