Quantitative magnetic resonance imaging assessment of cerebral ischemia inrat using on-resonance T-1 in the rotating frame

Sensitivity of T-1 in the rotating frame (T-1 rho) to both transient cerebr al ischemia and cortical hypoperfusion was studied in rats. T-1 rho is beli eved to probe water in close contact with macromolecules, revealing water s pins with restricted rotational mobility relative to bulk water. It is show n that T-1 rho increases within minutes of occlusion, thereby demonstrating it as a new, sensitive indicator of ischemia, After reperfusion at 90 minu tes of middle cerebral artery occlusion, T-1 rho remains elevated or increa ses in tissue destined to neuronal damage but returns to the normal level i f no neuronal damage develops within 24 hours. T-1 rho determined during th e first 2 hours of reperfusion shows a significant positive correlation wit h the ultimate neuronal damage score. However, T-1 rho is not affected by a cute hypoperfusion, These data show that, by combining three magnetic reson ance imaging coefficients, i.e. T-1 rho, T-2, and diffusion, viable hypoper fused areas that do not develop neuronal damage within 24 hours can be dist inguished correctly from tissue already destined for neuronal damage. Magn Reson Med 42:268-276, 1999. (C) 1999 Wiley-Liss, Inc.