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MAGNETIC RESONANCE IMAGING OF EXPERIMENTAL CEREBRAL ISCHEMIA : CORRELATIONS BETWEEN NMR PARAMETERS AND WATER CONTENT Hiroyuki Kato 1 , Kyuya Kogure 1 , Hitoshi Ohtomo 1 , Masahiro Izumiyama 1 , Muneshige Tobita 1 , Shigeru Matsui 2 , Etsuji Yamamoto 2 , Hideki Kohno 2 , Yoshinori Ikebe 3 , Takao Watanabe 4 1Department of Neurology, Institute of Brain Diseases, Tohoku University School of Medicine 2Central Research Laboratory, Hitachi Ltd. 3Hitachi Naka Works 4Department of Environmental Health, Tohoku University School of Medicine pp.295-302
Published Date 1986/3/1
DOI https://doi.org/10.11477/mf.1406205681
  • Abstract
  • Look Inside

Recent studies on proton NMR imaging revealed its remarkable sensitivity for detecting cerebral ischemia. Since proton NMR reflects the distribu-tion and state of water in the brain, an NMR imager becomes a sensitive in vivo detector of brain edema developing soon after the energy state is compromized by ischemia. To further cla-rify the usefulness of NMR imaging to characte-rize the ischemia-induced changes, correlations between T 1 and T 2 relaxation times and water content of the normal and ischemic rat and gerbil brain were studied by means of both spectroscopic and in vivo imaging methods.

In the spectroscopic experiment on excised rat brain (cortex, white matter, hippocampus and thalamus for normal and ischemia-laden brain), T 1 and T 2 relaxation times and water content were determined. The ischemic insult was induced for 60 min by the method of Pulsinelli followed by 60 min of reperfusion. All of the T 1, T 2 and water content significantly increased in the ischemic tis-sue. Gray-white difference was evident in T 1 and T 1 was linearly correlated with the water content of the tissue. T 2 was by far prolonged in the isc-hemic tissue compared with the increase in the water content, showing greater sensitivity of T 2 for detection of ischemia.

In the imaging experiment, coronal NMR ima-ging at O.5 tesla was performed employing proton density-weighted saturation recovery (TR =1.6 s, TE= 14 ms), T 1-weighted inversion recovery (TR =1.6 s, TI= 300 ms, TE= 14 ms) and T 2-weighted spin echo (TR =1.6 s, TE= 106 ms) pulse sequences. Spatial resolution of the images was excellent (0.3-0.5 mm) and the imaging of a gerbil brain clearly delineated anatomy separating cortex, whi- to matter, hippocampus and thalamus. Hemispheric ischemia of a gerbil brain was detected as early as 30 min after occlusion of the carotid artery in T 2-weighted images and the evolution of the le-sion was clearly picturized in T 1- and T 2-weight-ed images. On the other hand, SR images were far less sensitive. Calculated T 1 and T 2 relaxa-tion times by the pixel-to-pixel computation indi-cated progress of the lesion and excellently cor-related with the water content of the tissue (r= 0.892 and 0.744 for T 1 and T 2, respectively).

As a result, proton NMR imaging could detect cerebral ischemia as early as 30 min after insult in terms of early alteration of T 1 and T 2 relaxation times in the ischemic tissue. Furthermore, calcula-ted T 1 and T 2 values excellently correlated with the water content and were considered to be the in vivo indices of the dynamic state of water or the degree of the damage in the ischemic tissue.


Copyright © 1986, Igaku-Shoin Ltd. All rights reserved.

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電子版ISSN 2185-405X 印刷版ISSN 0006-8969 医学書院

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