title: Radiation-induced early changes in the brain and behavior: serial diffusion tensor imaging and behavioral evaluation after graded doses of radiation.
abstract: The nuclear arsenal and the use of nuclear technologies have enhanced the likelihood of whole-body/partial-body radiation exposure. The central nervous system is highly susceptible to even low doses of radiation. With the aim of detecting and monitoring the pathologic changes of radiation-induced damage in brain parenchyma, we used serial diffusion tensor magnetic resonance imaging (DTI) with a 7T magnetic resonance unit and neurobehavioral assessments mice irradiated with 3-, 5-, and 8-Gy doses of radiation. Fractional anisotropy (FA) and mean diffusivity (MD) values at each time point (baseline, day 1, day 5, and day 10) were quantified from hippocampus, thalamus, hypothalamus, cudate-putamen, frontal cortex, sensorimotor cortex, corpus callosum, cingulum, and cerebral peduncle. Behavioral tests were performed at baseline, day 5, and day 10. A decrease in FA values with time was observed in all three groups. At day 10, dose-dependent decreases in FA and MD values were observed in all of the regions compared with baseline. Behavioral data obtained in this study correlate with FA values. Radiation-induced affective disorders were not radiation dose dependent, insofar as the anxiety-like symptoms at the lower dose (3 Gy) mimics to the symptoms with the higher dose (8 Gy) level but not with the moderate dose. However, there was a dose-dependent decline in cognitive function as well as FA values. Behavioral data support the DTI indices, so it is suggested that DTI may be a useful tool for noninvasive monitoring of radiation-induced brain injury.
authors.affiliation: NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, India. triricha@gmail.com
authors.forename: Richa
authors.initials: R
authors.lastname: Trivedi
authors.forename: Ahmad Raza
authors.initials: AR
authors.lastname: Khan
authors.forename: Poonam
authors.initials: P
authors.lastname: Rana
authors.forename: Seenu
authors.initials: S
authors.lastname: Haridas
authors.forename: B S
authors.initials: BS
authors.lastname: Hemanth Kumar
authors.forename: Kailash
authors.initials: K
authors.lastname: Manda
authors.forename: Ram K S
authors.initials: RK
authors.lastname: Rathore
authors.forename: Rajendra P
authors.initials: RP
authors.lastname: Tripathi
authors.forename: Subash
authors.initials: S
authors.lastname: Khushu
mesh_terms: D000818:Animals; D016880:Anisotropy; D001522:Behavior, Animal / Q000528:radiation effects*; D001921:Brain / Q000528:radiation effects*; D001931:Brain Mapping; D056324:Diffusion Tensor Imaging; D004307:Dose-Response Relationship, Radiation; D005106:Exploratory Behavior / Q000528:radiation effects; D005720:Gamma Rays; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D021641:Recognition, Psychology / Q000528:radiation effects