title: Regional variation in brain white matter diffusion index changes following chemoradiotherapy: a prospective study using tract-based spatial statistics.
abstract: OBJECTIVE
  There is little known about how brain white matter structures differ in their response to radiation, which may have implications for radiation-induced neurocognitive impairment. We used diffusion tensor imaging (DTI) to examine regional variation in white matter changes following chemoradiotherapy.
  
  
  METHODS
  Fourteen patients receiving two or three weeks of whole-brain radiation therapy (RT) ± chemotherapy underwent DTI pre-RT, at end-RT, and one month post-RT. Three diffusion indices were measured: fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). We determined significant individual voxel changes of diffusion indices using tract-based spatial statistics, and mean changes of the indices within fourteen white matter structures of interest.
  
  
  RESULTS
  Voxels of significant FA decreases and RD increases were seen in all structures (p<0.05), with the largest changes (20-50%) in the fornix, cingula, and corpus callosum. There were highly significant between-structure differences in pre-RT to end-RT mean FA changes (p<0.001). The inferior cingula had a mean FA decrease from pre-RT to end-RT significantly greater than 11 of the 13 other structures (p<0.00385).
  
  
  CONCLUSIONS
  Brain white matter structures varied greatly in their response to chemoradiotherapy as measured by DTI changes. Changes in FA and RD related to white matter demyelination were prominent in the cingula and fornix, structures relevant to radiation-induced neurocognitive impairment. Future research should evaluate DTI as a predictive biomarker of brain chemoradiotherapy adverse effects.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan, United States of America. chchap@med.umich.edu
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Chapman
authors.forename: Mohammad
authors.initials: M
authors.lastname: Nazem-Zadeh
authors.forename: Oliver E
authors.initials: OE
authors.lastname: Lee
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Schipper
authors.forename: Christina I
authors.initials: CI
authors.lastname: Tsien
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.forename: Yue
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001932:Brain Neoplasms / Q000473:pathology* / Q000628:therapy; D059248:Chemoradiotherapy; D003071:Cognition / Q000187:drug effects / Q000528:radiation effects; D003337:Corpus Callosum / Q000187:drug effects / Q000473:pathology* / Q000528:radiation effects; D003711:Demyelinating Diseases; D056324:Diffusion Tensor Imaging; D005260:Female; D020712:Fornix, Brain / Q000187:drug effects / Q000473:pathology* / Q000528:radiation effects; D005720:Gamma Rays; D006179:Gyrus Cinguli / Q000187:drug effects / Q000473:pathology* / Q000528:radiation effects; D006801:Humans; D008297:Male; D008545:Melanoma / Q000473:pathology* / Q000628:therapy; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D011446:Prospective Studies
chemical_list: D000970:Antineoplastic Agents