Design of Differential Single‐Block and Multi‐Block Presaturated Ultrashort Echo Time Pulse Sequences for Fast and Flexible Short‐ <scp> T ₂ </scp> Imaging

PURPOSE: signals. Current UTE techniques are time-consuming and often require the acquisition of an inflexible volume. In this work, we implement new UTE sequences-differential single-block presaturated UTE (δSB-UTE) and differential multi-block presaturated UTE (δMB-UTE)-that combine spatial presaturation and subtraction to enable simultaneous multi-slice UTE acquisition with increased flexibility in field-of-view (FOV) and reduced scan times. METHODS: The sequences use a prepulse to presaturate blocks of magnetization and a whole-volume excitation to enable UTE acquisition. By shifting the saturation blocks and subtracting subsequent acquisitions, two and four simultaneous slices can be imaged with the δSB-UTE and δMB-UTE sequences, respectively. Design trade-offs were investigated in a phantom, and the sequences were used to image healthy volunteers at 3 T. RESULTS: resolution in 2.66 and 1.45 min, respectively. CONCLUSION: signal from the skull in multiple slices at the same time with an echo time of 0.18 ms. The δSB-UTE and δMB-UTE sequences enable the acquisition of a reduced through-plane FOV and reduce scan times for imaging bone.