title: Radiation induced brain injury: assessment of white matter tracts in a pre-clinical animal model using diffusion tensor MR imaging.
abstract: We aim to study radiation induced white matter injury in a pre-clinical model using Diffusion tensor MR imaging (DTI). Nineteen 12-week old Sprague-Dawley rats were irradiated to the right hemisphere using a linear accelerator. The dose distribution map was coregistered to the DTI map to generate the actual radiation dose to each white matter tract. Rats underwent longitudinal DTI scans at five time points from 4 to 48 weeks post-radiation with histological evaluations. Fractional anisotropy (FA) of the external capsule, fornix, cerebral peduncle, anterior commissure, optic tract and optic nerve was evaluated. Radiation dose was highest at the ipsilateral external capsule and fornix (29.4 ± 1.3 and 29.8 ± 1.1 Gy, respectively). Optic nerve received 50 % dose to the external capsule and other white matter tracts received 80 % dose. Significantly lower FA was firstly found in the ipsilateral external capsule at 4 weeks post-radiation and in the ipsilateral fornix at 40 weeks post-radiation compared to the contralateral side. Significantly lower FA was found in contralateral optic nerve compared to ipsilateral optic nerve at 48 weeks post-radiation despite ipsilateral optic nerves receiving higher radiation dose than contralateral optic nerve (p = 0.021). No differences were found in other white matter regions until 48 weeks. Histology indicated demyelination, axonal degeneration and coagulative necrosis in all injured white matter. DTI can serve as a promising tool for assessment of radiation induced white matter injury and regional radiosensitivity of white matter tracts.
authors: Department of Diagnostic Radiology, The University of Hong Kong, Room 406, Block K, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, Hong Kong. wangsilun@gmail.com
authors: Silun
authors: S
authors: Wang
authors: Deqiang
authors: D
authors: Qiu
authors: Kwok-Fai
authors: KF
authors: So
authors: Ed X
authors: EX
authors: Wu
authors: Lucullus H T
authors: LH
authors: Leung
authors: Jing
authors: J
authors: Gu
authors: Pek-Lan
authors: PL
authors: Khong
mesh_terms: D000818:Animals; D016880:Anisotropy; D001930:Brain Injuries / Q000209:etiology / Q000473:pathology*; D001931:Brain Mapping; D038524:Diffusion Magnetic Resonance Imaging; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007839:Functional Laterality; D007091:Image Processing, Computer-Assisted; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D016900:Neurofilament Proteins / Q000378:metabolism; D009460:Neurologic Examination; D011832:Radiation Injuries / Q000150:complications / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D016900:Neurofilament Proteins; C051774:neurofilament protein H