An Integrated Unipolar Ultrasonic Gradient for Mitigating PNS and aliasing in accelerated silent MRI

Motivation: In brain imaging with high-performance head-gradients, bipolar designs can lead to backfolding artifacts from the neck/shoulder regions. Additionally, the placement of one gradient pole near these areas increases the risk of PNS. Goal(s): An ultrasonic unipolar-gradient coil was designed to address both aliasing artifacts and PNS in neck/shoulder area. Approach: Tthe field-shape and acceleration performance were assessed by scanning a head-phantom with the unipolar-gradient coil. Results: The 2-layer unipolar-gradient coil generated a magnetic field with an efficiency of 0.25 mT/m with a 10% deviation over 16 cm FOV. In phantom scans, the ultrasonic unipolar-gradient enabled up to 8-fold acceleration without any aliasing artefacts. Impact: The presented ultrasonic unipolar gradient coil is designed to be plug-and-play and fit in an existing RF-transmit coil, ensuring ease-of-use while achieving a gradient-efficiency of 0.25 mT/m/A. The boost in gradient-performance can be used to yield fast and quiet scans.