Performance Analysis of the Inline Quantitative Cerebral Perfusion Measurements with MR

Introduction The American Heart Association has deemed the quantification of cerebral perfusion in stroke to be of paramount importance. Fast, accurate and automated determination of perfusion image maps is essential for analyzing tissue at risk after an ischemic stroke event [1,2]. The need for offline post-processing of Dynamic Susceptibility Contrast (DSC) images can delay the availability of time critical information (i.e. the extent of the perfusion diffusion mismatch predicts the response to intra venous thrombolysis in ischemic stroke). Therefore we have developed an inline protocol to eliminate the offline, time-consuming generation of perfusion maps. Currently, offline post-processing of DSC images requires specially trained personnel, additional workstations and introduces an unwanted delay in the generation of critical images. A reproducible, reliable and accurate method for producing quantitative values of cerebral perfusion using the parenchymal T1 changes has been developed [3-8] and validated [6]. Under normal circumstances, offline MR perfusion post-processing takes on average over >60min to generate quantitative cerebral blood flow (qCBF), quantitative cerebral blood volume (qCBV), and mean transit time (MTT) maps. In response, we developed and validated an inline software tool that has eliminated the offline post-processing steps and the associated latency between MR data acquisition and generation of quantified perfusion maps. Colormaps of qCBF, qCBV, and MTT are generated without additional personnel or workstations. Furthermore, this inline protocol reduces the interand the intra-operator variability. Time efficiency has been quantified by comparing our inline protocol with the clinical standard methods in a routine setting. The short 3 to 4.5 hour therapeutic window for administration of IV thrombolytic agents in the treatment of ischemic stroke underscores the need for a fast, reliable and reproducible postprocessing system.