Sensitivity and source of amine-proton exchange and amide-proton transfer magnetic resonance imaging in cerebral ischemia.
Sensitivity and source of amine-proton exchange and amide-proton transfer magnetic resonance imaging in cerebral ischemia.
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DOI：
10.1002/mrm.24639
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发表时间：
2014-01
影响因子：
3.3
通讯作者：
Jin, Tao
中科院分区：
文献类型：
--
作者：
Zong, Xiaopeng;Wang, Ping;Kim, Seong-Gi;Jin, Tao
关键词：
酰胺质子转移（APT）和胺-水质子交换（APEX）可以绘制ph降低的缺血区域。然而，他们的具体贡献尚不清楚。我们测量了9.4 t时永久性大脑中动脉闭塞大鼠的APEX和apt加权磁化传递比不对称性（记为APEXw和APTw）、ADC、T2和T1图像以及局部质子谱。闭塞后1小时内，APEXw和APTw图谱在ADC降低的区域分别显示高强度（M0的3.1%）和低强度（- 1.8%）。缺血增加乳酸和γ氨基丁酸（GABA）浓度，但降低谷氨酸和牛磺酸浓度。随着时间的推移，谷氨酸、牛磺酸和肌酸的APEXw对比降低，而APTw对比和乳酸水平相似。幻影和理论研究表明，APEXw信号的来源主要来自正常pH下的蛋白质，而在pH降低时，GABA和谷氨酸的贡献增加，导致缺血区域APEXw呈阳性对比。APTw对比剂对乳酸浓度和pH敏感，但受到更快的胺-水质子交换过程的影响。APEXw阳性比APTw阴性对缺血更敏感。它们可能提供互补的组织代谢信息。
Amide proton transfer (APT) and amine-water proton exchange (APEX) can be viable to map pH-decreasing ischemic regions. However, their exact contributions are unclear. We measured APEX- and APT-weighted magnetization transfer ratio asymmetry (denoted as APEXw and APTw), ADC, T2 and T1 images, and localized proton spectra in rats with permanent middle cerebral artery occlusion at 9.4 T. Phantoms and theoretical studies were also performed. Within one hour post-occlusion, APEXw and APTw maps showed hyperintensity (3.1% of M0) and hypointensity (−1.8%), respectively, in regions with decreased ADC. Ischemia increased lactate and gamma aminobutyric acid (GABA) concentrations, but decreased glutamate and taurine concentrations. Over time, the APEXw contrast decreased with glutamate, taurine and creatine, while the APTw contrast and lactate level were similar. Phantom and theoretical studies suggest that the source of APEXw signal is mainly from proteins at normal pH, while at decreased pH, GABA and glutamate contributions increase, inducing the positive APEXw contrast in ischemic regions. The APTw contrast is sensitive to lactate concentration and pH, but contaminated from contributions of the faster amine-water proton exchange processes. Positive APEXw contrast is more sensitive to ischemia than negative APTw contrast. They may provide complementary tissue metabolic information.
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影响因子：
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