Concurrent Four-Dimensional Dynamic MRA and Perfusion Imaging Using Dual-Module Arterial Spin Labeling MRI With Stack-Of-Stars Golden-Angle Radial Acquisition.

Arterial spin labeling (ASL) has been used for perfusion imaging and non-contrast enhanced dynamic MR angiography (MRA), and both have become favorable for clinical diagnosis and treatment planning of cerebrovascular diseases. Separate sequences are typically required to obtain brain vascular hemodynamics and downstream perfusion information. However, concurrent dynamic MRA and perfusion imaging within a single acquisition can provide spatially co-registered macrovascular and microvascular maps to enhance diagnostic confidence and efficiency. In this work, we developed a dual-module ASL technique to concurrently obtain four-dimensional (4D) MRA and cerebral perfusion images from a single scan. Specifically, pseudo-continuous ASL (pCASL) and pulsed ASL (PASL) modules were integrated and encoded with a 3D stack-of-stars golden-angle radial acquisition. 4D MRA and perfusion contrasts were generated through pair-wise subtractions. Sparsity-constrained image reconstruction was used in generating 4D MRA and perfusion images from different portions of radial k-space data. Both numerical simulationsL.  and in vivo experiments were performed to demonstrate technical feasibility. Both time-resolved MRA with high spatiotemporal resolution and perfusion-weighted images with good contrast were successfully obtained from a single scan using the proposed dual-module ASL technique. The performance of the proposed technique was compared against the reference 4D MRA technique in terms of vascular delineation and blood flow dynamics, and the conventional pCASL perfusion imaging with 3D GRASE for cerebral blood flow (CBF) measurement. The dual-module ASL showed comparable performance in depicting arterial blood flow dynamics and gray matter CBF quantification (p = 0.73) to the reference 4D MRA and 3D GRASE pCASL, respectively. These results indicate the feasibility of the proposed technique for concurrent 4D MRA and perfusion imaging from a single scan, which could be a potentially powerful imaging tool for the detailed characterization of dynamic blood flow patterns through the cerebrovascular structure and downstream perfusion.