期刊
JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM
卷 29, 期 1, 页码 206-216出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/jcbfm.2008.113
关键词
adiabatic pulses; brain; stroke; T-1 rho and T-2 rho relaxation
资金
- Sigrid Juselius Foundation
- Academy of Finland
- Finnish Funding Agency for Technology and Innovation (TEKES)
- Emil Aaltonen Foundation
- Finnish Cultural Foundation of Northern Savo
- NIH [P41 RR008079, P30 NS057091]
- NATIONAL CENTER FOR RESEARCH RESOURCES [P41RR008079] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF BIOMEDICAL IMAGING AND BIOENGINEERING [P41EB015894] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE [P30NS057091] Funding Source: NIH RePORTER
The rotating frame longitudinal relaxation magnetic resonance imaging (MRI) contrast, T-1 rho, obtained with on-resonance continuous wave (CW) spin-lock field is a sensitive indicator of tissue changes associated with hyperacute stroke. Here, the rotating frame relaxation concept was extended by acquiring both T-1 rho and transverse rotating frame (T-2 rho) MRI data using both CW and adiabatic hyperbolic secant (HSn; n = 1, 4, or 8) pulses in a rat stroke model of middle cerebral artery occlusion. The results show differences in the sensitivity of spin-lock T1 rho and T-2 rho MRI to detect hyperacute ischemia. The most sensitive techniques were CW-T-1 rho and T-1 rho using HS4 or HS8 pulses. Fitting a two-pool exchange model to the T-1 rho and T-2 rho MRI data acquired from the infarcting brain indicated time-dependent increase in free water fraction, decrease in the correlation time of water fraction associated with macromolecules, and increase in the exchange correlation time. These findings are consistent with known pathology in acute stroke, including vasogenic edema, destructive processes, and tissue acidification. Our results show that the sensitivity of the spin-lock MRI contrast in vivo can be modified using different spin-lock preparation blocks, and that physicochemical models of the rotating frame relaxation may provide insight into progression of ischemia in vivo.
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