title: White matter anisotropy in childhood medulloblastoma survivors: association with neurotoxicity risk factors.
abstract: OBJECTIVE
  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.
  
  
  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 (DeltaFA) in each patient. Spearman rank correlation analysis was used to analyze the relationships between DeltaFA 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 DeltaFA.
  
  
  RESULTS
  There were significant correlations between DeltaFA and both age at CSI (r = 0.631, P = .003) and CSI dose (r = -0.586, P = .007) but not between DeltaFA and time of MR imaging since CSI. Multiple linear regression analysis revealed age at CSI to be the only independent variable that significantly affected DeltaFA (adjusted r2= 0.391, P = .012).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Diagnostic Radiology, Queen Mary Hospital, University of Hong Kong, Block K, Room 406, 102 Pokfulam Rd, Hong Kong, China. plkhong@hkucc.hku.hk
authors.forename: Pek-Lan
authors.initials: PL
authors.lastname: Khong
authors.forename: Lucullus H T
authors.initials: LH
authors.lastname: Leung
authors.forename: Godfrey C F
authors.initials: GC
authors.lastname: Chan
authors.forename: Dora L W
authors.initials: DL
authors.lastname: Kwong
authors.forename: Wilfred H S
authors.initials: WH
authors.lastname: Wong
authors.forename: Guang
authors.initials: G
authors.lastname: Cao
authors.forename: Gaik-Cheng
authors.initials: GC
authors.lastname: Ooi
mesh_terms: D000293:Adolescent; D016880:Anisotropy; D002528:Cerebellar Neoplasms / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008527:Medulloblastoma / Q000473:pathology*; D020258:Neurotoxicity Syndromes; D011446:Prospective Studies; D012307:Risk Factors; D017741:Survivors