title: MRI and PET of delayed heavy-ion radiation injury in the rabbit brain.
abstract: Magnetic resonance imaging (MRI) and positron emission tomography (PET) techniques were used to obtain in vivo scans of delayed (30 GyE helium ion, 230 MeV/u) radiation injury in rabbit brain. T2-weighted (T2W) MRI scans demonstrated alterations that were restricted primarily to the white matter tracts and the deep perithalamic and thalamic regions. Quantitative measurements of T2 and T1 values demonstrated wide variations in absolute values. However, paired comparisons in hemibrain-irradiated rabbits revealed significant increases in T2 (p less than 0.001) and T1 (p less than 0.01) in irradiated versus unirradiated brain. Gadolinium DTPA (GdDTPA) enhanced MRI and 82Rubidium (82Rb) PET detected focal regions of blood-brain barrier (BBB) disruption restricted to the deep white matter and thalamic regions. Sequential GdDTPA enhanced MRI scans showed the spreading of the tracer from the initial site of contrast enhancement. 18Fluorodeoxyglucose (18FDG) PET studies demonstrated the markedly depressed metabolic profiles of irradiated brain. Histological findings of tissue edema and necrosis correlated well with the in vivo imaging abnormalities. These initial studies demonstrate that the irradiated rabbit brain is a suitable animal model for examining the delayed effects of radiation injury in the brain.
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, CA 94305.
authors.forename: E H
authors.initials: EH
authors.lastname: Lo
authors.forename: R L
authors.initials: RL
authors.lastname: DeLaPaz
authors.forename: K A
authors.initials: KA
authors.lastname: Frankel
authors.forename: A
authors.initials: A
authors.lastname: Poljak
authors.forename: M H
authors.initials: MH
authors.lastname: Phillips
authors.forename: K M
authors.initials: KM
authors.lastname: Brennan
authors.forename: K H
authors.initials: KH
authors.lastname: Woodruf
authors.forename: P E
authors.initials: PE
authors.lastname: Valk
authors.forename: G K
authors.initials: GK
authors.lastname: Steinberg
authors.forename: J I
authors.initials: JI
authors.lastname: Fabrikant
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects*; D003287:Contrast Media; D005682:Gadolinium; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009942:Organometallic Compounds; D004369:Pentetic Acid; D011817:Rabbits; D011833:Radiation Injuries, Experimental / Q000000981:diagnostic imaging / Q000473:pathology*; D012414:Rubidium Radioisotopes; D014055:Tomography, Emission-Computed / Q000379:methods
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D012414:Rubidium Radioisotopes; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA