White matter anisotropy in childhood medulloblastoma survivors: Association with neurotoxicity risk factors

Abstract

PURPOSE: To prospectively evaluate the relationships between change in white matter (WM) anisotropy and (a) patient age at craniospinal irradiation (CSI), (b) CSI dose, and (c) time of magnetic resonance (MR) imaging since CSI and to determine the effect of these neurotoxicity risk factors on WM anisotropy in posttreatment medulloblastoma survivors. MATERIALS AND METHODS: Informed consent was obtained from the patients, control subjects, or their parents, and the study was approved by the institutional review board. Twenty consecutive medulloblastoma survivors (14 male, six female; mean age, 11.0 years ± 4.6 [standard deviation]) and 36 control subjects (14 male, 22 female; mean age, 10.7 years ± 3.5) were examined. Control subjects were divided into four groups according to age: 5.0-7.9 years, 8.0-10.9 years, 11.0-13.9 years, and 14.0-18.9 years. The authors calculated the histogram-derived mean WM fractional anisotropy (FA) value for each patient and compared it with the mean WM FA value for the control subjects in the corresponding age group to evaluate the percentage change in WM FA (ΔFA) in each patient. Spearman rank correlation analysis was used to analyze the relationships between ΔFA and (a) age at CSI, (b) CSI dose, and (c) time of MR imaging since CSI. Then, multiple linear regression analysis was performed to study the simultaneous influence of these factors on ΔFA. RESULTS: There were significant correlations between ΔFA and both age at CSI (r = 0.631, P = .003) and CSI dose (r = -0.586, P = .007) but not between ΔFA and time of MR imaging since CSI. Multiple linear regression analysis revealed age at CSI to be the only independent variable that significantly affected ΔFA (adjusted r 2 = 0.391, P = .012). CONCLUSION: Loss of WM anisotropy is significantly affected by age at CSI, and there is a trend toward increasing anisotropy loss with larger CSI dose. Both age at CSI and CSI dose are known risk factors of neurotoxicity. © RSNA, 2005.