Quantitative assessment of water pools by T1ρ and T2ρ MRI in acute cerebral ischemia of the rat
Quantitative assessment of water pools by T1ρ and T2ρ MRI in acute cerebral ischemia of the rat
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DOI：
10.1038/jcbfm.2008.113
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发表时间：
2009-01-01
影响因子：
6.3
通讯作者：
Groehn, Olli H.
中科院分区：
文献类型：
--
作者：
Jokivarsi, Kimmo T.;Niskanen, Juha-Pekka;Groehn, Olli H.
旋转框架纵向弛豫磁共振成像（MRI）对比度，T-1 rho，获得与共振连续波（CW）自旋锁定场是一个敏感的指标与超急性中风相关的组织变化。在这里，旋转框架松弛的概念是通过在大鼠大脑中动脉闭塞中风模型中使用CW和绝热双曲正割（HSn; n = 1，4或8）脉冲采集T-1 rho和横向旋转框架（T-2 rho）MRI数据来扩展的。结果显示自旋锁T1 rho和T-2 rho MRI检测超急性缺血的灵敏度存在差异。最敏感的技术是使用HS 4或HS 8脉冲的CW-T-1 rho和T-1 rho。将两池交换模型拟合到从梗塞脑获得的T-1 rho和T-2 rho MRI数据表明游离水分数的时间依赖性增加，与大分子相关的水分数的相关时间减少，以及交换相关时间增加。这些发现与急性卒中的已知病理学一致，包括血管源性水肿、破坏性过程和组织酸化。我们的研究结果表明，自旋锁MRI对比度在体内的灵敏度可以修改使用不同的自旋锁制备块，和旋转框架松弛的物理化学模型可以提供洞察缺血在体内的进展。
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.