Recent advances in MR imaging/spectroscopy of cerebral ischemia.

Abstract

Recent advances in high-resolution MR imaging and multinuclear spectroscopy have stimulated studies of the functional relationships between tissue hypoperfusion, cellular energy depletion, and brain edema associated with cerebral ischemia. The very slow (microns/sec) random translational motion of water protons in various brain tissues and intracranial fluid compartments can now be assessed with MR diffusion imaging. More slowly diffusing protons in ischemic tissues can be differentiated from normal parenchyma, CSF, and flowing blood, enabling the detection and localization of ischemic regions within minutes of the onset of stroke. Perfusion imaging "snapshots," obtained in as little as 25 msec with echoplanar MR methods, permit the evaluation of tissue washin/washout kinetics of contrast agents in the microvasculature, and thus the quantification of brain perfusion on a regional basis. Also, delineation of major intra- and extracranial arterial and venous structures with MR angiography, acquired with two...