Quantitative T-2* and T-2 ' maps during reversible focal cerebral ischemiain rats: Separation of blood oxygenation from nonsusceptibility-based contributions

Quantitative imaging contrast is evaluated which allows the selective measu rement of the blood oxygenation state during cerebral ischemia within a mul tiparametric imaging study on rats. In a first step, the ambiguities arisin g in T*(2)-weighted Images due to T*(2) heterogeneity are eliminated by cal culating T*(2) maps. Then, 1/T'(2) maps are calculated according to 1/T'(2) = 1/T*(2) - 1/T-2 to eliminate nonsusceptibility-induced changes of 1/T*(2 ) after the induction of stroke. This is of particular importance in the pr esence of vasogenic edema. The changes Delta(1/T'(2)) after the onset of is chemia selectively quantify the variations of the deoxyhemoglobin content d uring the development of the infarct. The presented results are not availab le from conventionally recorded parameters of a stroke study and, together with perfusion-weighted images, form a powerful combination to analyze the oxygen consumption and the metabolism of the tissue. (C) 1999 Wiley-Liss, I nc.