Perfusion MRI of infarcted and noninfarcted brain tissue in stroke - A comparison of conventional hemodynamic imaging and factor analysis of dynamic studies

RATIONALE AND OBJECTIVES. TO investigate the hemodynamics of infarcted and noninfarcted regions of the brain in patients with stroke secondary to a co mplete middle cerebral artery occlusion, Also, to compare factor analysis, a novel method of analyzing perfusion-weighted images, with more convention al techniques, METHODS. Twenty-two patients with complete unilateral occlusion of the midd le cerebral artery were examined by T1-weighted, contrast-enhanced, perfusi on-weighted imaging, diffusion- weighted imaging, and magnetic resonance an giography, Quantitative cerebral blood volume (CBV), cerebral blood flow (C BF), and time-to-peak-intensity (TTP) images were generated. Factor analysi s of dynamic studies (FADS) was used to generate "early" and "late" images. The hemodynamic parameters for the infarcted and noninfarcted regions of t he occluded territory were compared with those for the brain territory on t he nonoccluded side. RESULTS. Three regions were shown: (1) Normal tissue on the unaffected side ; (2) an infarcted region, which was characterized by reduced CBV, CBF, and early FADS values with increased TTP values; and (3) a noninfarcted region with reduced early FADS and increased late FADS and TTP values compared wi th the normal region, Cerebral blood volume and CBF values were not reduced significantly in the noninfarcted region. CONCLUSIONS. The differences in parameters such as TTP, CBV, and CBF are si gnificant, and it is necessary to use more than one parameter when interpre ting magnetic resonance imaging perfusion data. Factor analysis of dynamic studies provides additional information to conventional methods of analyzin g perfusion data.