Quantitative cerebral perfusion with SCALE-PWI: Accelerated image acquisition and optimized image reconstruction

INTRODUCTION Quantitative cerebral perfusion is a fundamental physiologic parameter that reflects the severity and progression of a broad range of pathologies, such as stroke, cancer, Alzheimer’s Disease, cerebrovascular occlusive disease, and multiple sclerosis. An accelerated and simplified implementation of the multi-scan Bookend technique [1,2], which has been shown to provide reproducible, reliable and accurate quantitative cerebral perfusion values [2,3], has been made possible through a SelfCALibrated Epi Perfusion Weighted Imaging (SCALE-PWI) MRI pulse sequence [4]. In one sequence, SCALE-PWI acquires inversion recovery (IR) Look-Locker (LL) EPI modules for a single “calibration” slice containing white matter (WM), before and after a conventional gradient-echo (GRE) EPI dynamic susceptibility contrast (DSC) scan with a gadolinium-based contrast bolus injection, resulting in a total scan time under 2 minutes. SCALE-PWI eliminates the need for technologist training, reduces motion artifacts, and provides the possibility of on-site, inline reconstruction of quantitative images of cerebral perfusion. A study of two different delay times between consecutive SCALE-PWI modules and a water exchange correction parameterization for SCALE-PWI at 1.5 T are presented in this work, which results in accelerating image acquisition and making quantitative perfusion reconstruction of SCALE-PWI more robust and ready for use in clinical settings.