Single-shot spiral MR-ARFI with Model-Based Displacement Map Reconstruction in Non-Human Primates

Motivation: MR-ARFI visualizes the ultrasound focus for targeting ultrasound neuromodulation, but has poor sensitivity when used within FDA mechanical index (MI) limits. Goal(s): Implement a recent single-shot spiral MR-ARFI method, evaluate it in non-human primates, and make it robust to dynamic phase errors. Approach: A single-shot spiral interleaved MR-ARFI pulse sequence was implemented to acquire data in NHP brain. A model-based reconstruction was developed. Results: The spiral sequence detected displacement at an MI of 1.2, well below the FDA limit of 1.9, which 3D EPI could not detect. The model-based reconstruction suppressed background phase errors and maximized precision. Impact: Used within current FDA limits, MR-ARFI has poor sensitivity for visualizing the ultrasound focus to target neuromodulation. We show that a recent spiral MR-ARFI method enables focus visualization in vivo within limits, and we maximize its sensitivity with model-based reconstruction.