title: Diffusion and perfusion magnetic resonance imaging following closed head injury in rats.
abstract: Diffusion-, perfusion-, T1-, and T2-weighted magnetic resonance imaging (MRI) were performed at 1-2 h, 24 h, and 1 week following closed head injury (CHI) in rats, and data was compared with hematoxylin and eosin histology. At 1-2 h, large areas of low perfusion in the damaged hemisphere overestimate the histological damage. In the first 2 h, the histological damage seems to be a superposition of abnormalities in the T1- and diffusion-weighted images. In areas with more than 10% reduction in the apparent diffusion coefficients (ADCs), reduced regional cerebral blood volume (r-CBV) was also observed. The decrease in ADCs and rCBV correlated with r = 0.78. Changes in the MRI parameters revealed the following: (a) Further reduction in ADC occurred from 83+/-15% at 1-2 h after trauma to 69+/-9% at 24 h, and 1 week later a marked elevation in the ADC values is observed. (b) Blood perfusion measurements performed 1-2 h posttrauma revealed a pronounced reduction in r-CBV (53+/-18%) in the damaged hemisphere in all rats. At 24 h postimpact, areas of hyper- and hypoperfusion were observed. One week later, similar perfusion was found in both hemispheres of all rats. (c) T2 hyperintensity at 24 h overestimated the histological damage found at 1 week. At one week following the trauma, the T2 hyperintensity underestimated the histological damage. It is concluded that CHI, which is a heterogeneous insult, should be studied by a combination of MRI techniques. The superposition of the abnormalities seen on T1 and on the diffusion-weighted MR images at early time point represents best the histological damage. Both T2 and rCBV images are less informative in terms of actual histological damage.
authors.affiliation: School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Assaf
authors.forename: A
authors.initials: A
authors.lastname: Holokovsky
authors.forename: E
authors.initials: E
authors.lastname: Berman
authors.forename: Y
authors.initials: Y
authors.lastname: Shapira
authors.forename: E
authors.initials: E
authors.lastname: Shohami
authors.forename: Y
authors.initials: Y
authors.lastname: Cohen
mesh_terms: D000818:Animals; D001810:Blood Volume; D001921:Brain / Q000473:pathology; D002560:Cerebrovascular Circulation; D006259:Craniocerebral Trauma / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D004058:Diffusion; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors