RAZER: A pulse sequence for whole‐brain bolus tracking at high frame rates

Abstract

To introduce a pulse sequence that obtains whole-brain perfusion measurements at 1.7 mm isotropic voxel resolution by dynamic susceptibility contrast MRI bolus tracking despite using a temporal resolution of 10.3 s: RAdial kZ-blipped 3D GRE-echo-planar imaging (GRE-EPI) for whole-brain pERfusion (RAZER). In RAZER, in-plane radial and through-plane 3D GRE-EPI Cartesian sampling was used to produce a 3D stack-of-stars k-space. In vivo scans on one healthy volunteer and one patient with Moyamoya disease were performed using RAZER and a typical 2D GRE-EPI pulse sequence as a reference standard. Agreement in perfusion metrics was reported using linear regression analysis and Bland-Altman plots. Sliding window reconstruction recovered dynamic information lost in the large temporal acquisition window of RAZER. Inline phase correction scans corrected N/2 ghosting artifacts and view-dependent phase variations. Whole-brain images of cerebral blood volume, cerebral blood flow, and mean transit time were calculated with RAZER at 1.7 mm isotropic voxel resolution and good reference standard agreement in both subjects when sliding window reconstruction was used (r(2) > 0.7, mean bias in mean transit time measurements < 0.5 s). Despite using a temporal resolution of 10.3 s, in vivo data indicates that RAZER is able to obtain whole-brain perfusion measurements at 1.7 mm isotropic voxel resolution and good reference standard agreement.