Article

Interrelations of T(1) and diffusion of water in acute cerebral ischemia of the rat.

NMR Research Group, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland.
Magnetic Resonance in Medicine (impact factor: 2.96). 01/2001; 44(6):833-9. pp.833-9
Source: PubMed

ABSTRACT Interrelation of T(1) and diffusion of water was studied in rat models of acute global and focal cerebral ischemia. Cortical T(1), as quantified with an inversion recovery method, increased by 4-7% within a few minutes of global ischemia at 4.7 and 9.4 T, but a significantly smaller change was detected at 1.5 T. The initial T(1) change occurred within seconds of cardiac arrest, much earlier than the extensive diffusion drop after 1-2 min. Thus, the initial increase in T(1) upon acute cerebral ischemia is directly caused by cessation of blood flow. In transient middle cerebral artery occlusion (MCAO), prolonged T(1) relaxation was detected within 10 min, with a subsequent increase during the course of ischemia. Spin density did not change during the first hour, showing that T(1) increase was not caused by net accumulation of water. Interestingly, partial recovery of T(1) upon release of MCAO, occurring independent of long-term tissue outcome, was observed only in concert with diffusion recovery.

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    Article: ADC characterization of region-specific response to cerebral perfusion deficit in rats by MRI at 9.4 T.
    Victor E Yushmanov, Lei Wang, Serguei Liachenko, Pei Tang, Yan Xu
    [show abstract] [hide abstract]
    ABSTRACT: Region-specific cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) of water in the rat brain were quantified in vivo by high-field MRI (9.4 T) for 6-7 h after middle cerebral artery occlusion (MCAO). Upon occlusion, average CBF fell from about 1.5-2 ml/g/min to below 0.5 ml/g/min in cortical areas and the amygdala, and below 0.2 ml/g/min in the caudate putamen. CBF in some of the homologous contralateral areas also decreased by 20-30%. Average ADC decreased from about 8 center dot 10(-4) to 5 center dot 10(-4) mm(2)/s in the caudate putamen and parietal cortex. Corresponding changes in ADC were lower in the frontal cortex and negligible in the piriform cortex, suggesting that the perfusion threshold for ADC decrease may be different for different brain regions in the same animal. The area of decreased ADC correlated well with the infarction area revealed by 2,3,5-triphenyltetrazolium chloride (TTC) staining of brain slices in vitro. A better understanding of the mechanisms linking ADC and CBF changes to ischemic cell disorders may prove useful in characterizing the degree of tissue damage, and in developing and evaluating treatment strategies.
    Magnetic Resonance in Medicine 04/2002; 47(3):562-70. · 2.96 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

acute cerebral ischemia
 
acute global
 
blood flow
 
Cortical T(1)
 
diffusion
 
diffusion recovery
 
extensive diffusion drop
 
focal cerebral ischemia
 
global ischemia
 
independent
 
inversion recovery method
 
long-term tissue outcome
 
MCAO
 
net accumulation
 
partial recovery
 
rat models
 
smaller change
 
Spin density
 
subsequent increase
 
transient middle cerebral artery occlusion