Evaluating the capabilities and challenges of layer-fMRI VASO at 3T

In this work, we propose the application of vein-free vascular space occupancy (VASO) sequences at widely accessible 3T scanners. We aim to implement, characterize and apply a CBV-sensitive VASO sequence setup for 3T. We find that the longer T2*, and shorter T1 relaxation times at 3T can account for some of the lower z-magnetization in the inversion-recovery VASO sequence compared to 7T and 9.4T.

Since 3T fMRI does not provide as much SNR compared to 7T, thermal-noise dominated layer-fMRI experiments at 3T require longer scan duration. In order to mitigate unrealistically long experiments, we aimed to increase the readout efficiency compared to previous 7T layer-fMRI VASO. This is done by means of utilizing fat saturation with binomial pulses, and segmented in-plane segmented trajectory, and externalizing phase navigators from the shot-specific readout.

We test the utility of this setup for visual tasks, for motor tasks, and for movie watching tasks. We conclude that layer-fMRI VASO is applicable at 3T without too much further ado. Link to Zip file with all participants (96GB): layerfmri.page.link/3TVASO_groupdata