The Performance of MRI-Based Cerebral Blood Flow Measurements in Acute and Subacute Stroke Compared With 15O-Water Positron Emission Tomography

Background and Purpose— Perfusion-weighted MRI-based maps of cerebral blood flow (CBFMRI) are considered a good MRI measure of penumbral flow in acute ischemic stroke but are seldom used in clinical routine due to methodical issues. We validated CBFMRI on quantitative CBF measurement by 15O-water positron emission tomography (CBFPET). Material and Methods— Comparative CBFMRI and CBFPET were performed in patients with acute and subacute stroke. In a voxel-based seed-growing technique, predefined CBFMRI thresholds (<40, <30, <20, <10 mL/100 g/min) were applied and the resulting volumes were compared with the hypoperfusion volume detected by the penumbral threshold (<20 mL/100 g/min) on CBFPET. The volumetric comparison was expressed as the C-ratio (volume CBFMRI/volume CBFPET) to identify the best MRI threshold. The influence of vessel pathology, hypoperfusion size, and time point of imaging was described. The proportion of voxels correctly classified as hypoperfused and the proportion of voxel correctly cl...