title: Multi-component diffusion characterization of radiation-induced white matter damage.
abstract: OBJECTIVE
  We used multi-b-value diffusion models to characterize microstructural white matter changes after brain radiation into fast and slow components, in order to better understand the pathophysiology of radiation-induced tissue damage.
  
  
  METHODS
  Fourteen patients were included in this retrospective analysis with imaging prior to, and at 1, 4-5, and 9-10 months after radiotherapy (RT). Diffusion signal decay within brain white matter was fit to a biexponential model to separate changes within the slow and fast components. Linear mixed-effects models were used to obtain estimates of the effect of radiation dose and time on the model parameters.
  
  
  RESULTS
  We found an increase of 0.11 × 10-4and 0.14 × 10-4mm2/s in the fast diffusion coefficient per unit dose-time (Gy-month) in the longitudinal and transverse directions, respectively. By contrast, the longitudinal slow diffusion coefficient decreased independently of dose, by 0.18 × 10-4, 0.16 × 10-4, and 0.098 × 10-4mm2/s at 1, 4, and 9 months post-RT, respectively.
  
  
  CONCLUSIONS
  Radiation-induced white matter changes in the first year following RT are driven by dose-dependent increases in the fast component and dose-independent decreases in the slow component.
authors.affiliation: Department of Radiation Medicine and Applied Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Roshan A
authors.initials: RA
authors.lastname: Karunamuni
authors.affiliation: Department of Radiology, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: White
authors.affiliation: Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Carrie R
authors.initials: CR
authors.lastname: McDonald
authors.affiliation: Department of Radiation Medicine and Applied Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Connor
authors.affiliation: Department of Radiation Medicine and Applied Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Niclas
authors.initials: N
authors.lastname: Pettersson
authors.affiliation: Department of Radiation Medicine and Applied Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Tyler M
authors.initials: TM
authors.lastname: Seibert
authors.affiliation: Department of Radiology, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Kuperman
authors.affiliation: Department of Radiology, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Nikdokht
authors.initials: N
authors.lastname: Farid
authors.affiliation: Department of Radiation Medicine and Applied Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Vitali
authors.initials: V
authors.lastname: Moiseenko
authors.affiliation: Department of Radiology, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
authors.affiliation: Department of Radiation Medicine and Applied Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California, 92093, USA.
authors.forename: Jona A
authors.initials: JA
authors.lastname: Hattangadi-Gluth
mesh_terms: D001921:Brain; D001932:Brain Neoplasms / Q000532:radiotherapy*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D012189:Retrospective Studies; D066127:White Matter / Q000473:pathology* / Q000528:radiation effects
keywords: biexponential; diffusion MRI; radiation; white matter