Toward efficient arterial spin labeling imaging of knee bone marrow at 7T by utilizing a localized parallel transmit water excitation pulse design

Motivation: To make knee bone marrow arterial spin labeling (ASL) imaging a viable and clinically practical approach. Goal(s): To increase knee bone marrow ASL imaging signal-to-noise efficiency and quality by using parallel transmit spatial-spectral localized water excitation pulses for ASL image readouts. Approach: Spatial-spectral water excitation pulses inside a 2D arbitrarily-shaped region of interest were designed and validated in a knee phantom and healthy volunteers using an 8-channel transceiver knee coil. Results: The designed spatial-spectral pulses could produce localized water excitation inside targeted regions with effective fat suppression. Impact: The validated pulse design provides an effective way for localized water excitation and eliminate the need for additional fat saturation with reduced RF power deposition, having a great potential to improve knee ASL imaging efficiency at ultrahigh field.