Combined angiography and perfusion using radial imaging and arterial spin labeling with structural contrast

To develop a non-contrast MRI method for the simultaneous acquisition of time-resolved 3D angiographic, perfusion, and multi-contrast T1-weighted structural brain images in a single 6 min acquisition. The proposed combined angiography and perfusion using radial imaging and arterial spin labeling with structural contrast (CAPRIA+S) pulse sequence uses pseudocontinuous arterial spin labeling to label inflowing blood, an inversion pulse to provide background suppression and T1-weighted contrast, and a continuous 3D golden ratio spoiled gradient echo readout. Label-control subtraction isolates the blood signal which can be flexibly reconstructed at high/low spatiotemporal resolution for angiography/perfusion imaging. The mean signal retains the static tissue, allowing T1-weighted structural images to be reconstructed at different effective TIs. CAPRIA+S was compared with conventional time-of-flight angiography, 3D-gradient and spin echo pseudocontinuous arterial spin labeling perfusion imaging, and MPRAGE structural imaging (10 min total) in healthy volunteers. CAPRIA+S gave improved distal vessel visibility and fewer artifacts than time-of-flight angiography, while also providing dynamic information, with blood transit time and dispersion maps. CAPRIA+S perfusion images were comparable to 3D-gradient and spin echo data but without through-slice blurring or artifacts in inferior brain regions. Comparable quantitative cerebral blood flow maps were produced, with CAPRIA+S being significantly more repeatable. Structural CAPRIA+S images were comparable to MPRAGE but also yielded a range of T1-weighted contrasts and allowed quantitative T1 maps to be estimated. CAPRIA+S is an efficient single acquisition to provide intrinsically co-registered quantitative information about brain blood flow and structure that has considerable advantages over conventional methods.