Combining the benefits of 3D acquisitions and spiral readouts for VASO fMRI at UHF

Abstract We present a slice-saturation slab-inversion VASO (SS-SI-VASO) sequence with a 3D stack-of-spirals readout implemented in Pulseq and show that it can accurately capture changes in cerebral blood volume. Its performance is compared to a state-of-the-art SS-SI-VASO sequence with a 3D EPI readout. We observed an increase in tSNR and improvement in z-scores in spiral compared to 3D EPI acquisition, demonstrating that spiral readouts are suitable for CBV-weighted laminar fMRI. Additionally, we found an increase in sensitivity and relative specificity with the proposed method using spiral readouts, compared to EPI readouts. Several correction approaches were employed in the spiral reconstruction to improve image quality. Incidentally, BOLD contrast in the proposed short-TE spirals is almost as high as that of the 3D EPI at longer TE. In this work, we demonstrate that spiral readouts are promising especially in applications where there is a need for short TE, such as mesoscopic fMRI at higher fields. The vendor-agnostic Pulseq implementation of VASO together with an open-source reconstruction framework, aims at increasing the availability and utilization of VASO in high-resolution fMRI experiments.