在急性脑卒中动物模型中进行磁化传递和弛豫归一化 pH 特异脉冲酰胺质子转移成像的演示。

Demonstration of magnetization transfer and relaxation normalized pH-specific pulse-amide proton transfer imaging in an animal model of acute stroke.

机构信息

Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.

Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA.

出版信息

Magn Reson Med. 2020 Sep;84(3):1526-1533. doi: 10.1002/mrm.28223. Epub 2020 Feb 20.

PURPOSE

pH-weighted amide proton transfer (APT) MRI is promising to serve as a new surrogate metabolic imaging biomarker for refined ischemic tissue demarcation. APT MRI with pulse-RF irradiation (pulse-APT) is an alternative to the routine continuous wave (CW-) APT MRI that overcomes the RF duty cycle limit. Our study aimed to generalize the recently developed pH-specific magnetization transfer and relaxation-normalized APT (MRAPT) analysis to pulse-APT MRI in acute stroke imaging.

METHODS

Multiparametric MRI, including CW- and pulse-APT MRI scans, were performed following middle cerebral artery occlusion in rats. We calculated pH-sensitive MTR and pH-specific MRAPT contrast between the ipsilateral diffusion lesion and contralateral normal area.

RESULTS

An inversion pulse of 10 to 15 ms maximizes the pH-sensitive MRI contrast for pulse-APT MRI. The contrast-to-noise ratio of pH-specific MRAPT effect between the contralateral normal area and ischemic lesion from both methods are comparable (3.25 ± 0.65 vs. 3.59 ± 0.40, P > .05). pH determined from both methods were in good agreement, with their difference within 0.1.

CONCLUSIONS

Pulse-APT MRI provides highly pH-specific mapping for acute stroke imaging.

目的

pH 值加权酰胺质子转移（APT）MRI 有望成为一种新的代谢成像替代生物标志物，用于更精细的缺血组织边界界定。与常规连续波（CW-）APT MRI 相比，具有脉冲射频辐射（pulse-APT）的 APT MRI 克服了 RF 占空比限制。我们的研究旨在将最近开发的 pH 特异性磁化转移和弛豫归一化 APT（MRAPT）分析推广到急性中风成像中的脉冲 APT MRI。

方法

在大鼠大脑中动脉闭塞后进行多参数 MRI，包括 CW-和脉冲-APT MRI 扫描。我们计算了同侧弥散病变与对侧正常区域之间 pH 敏感的 MTR 和 pH 特异性 MRApt 对比。

结果

10 到 15 毫秒的反转脉冲可最大限度地提高脉冲 APT MRI 的 pH 敏感 MRI 对比度。两种方法之间正常区域与缺血病变的 pH 特异性 MRApt 效应的对比噪声比相当（3.25±0.65 与 3.59±0.40，P＞0.05）。两种方法确定的 pH 值一致性较好，差值在 0.1 以内。