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Abstract #0468

Estimating Variations in SAR Calculations due to Within-Scan Patient Motion Using cGANs for Parallel RF Transmission at Ultrahigh Field MRI

Katherine Anna Blanter1, Alix Plumley1, Shaihan Malik2, and Emre Kopanoglu1
1Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, United Kingdom, 2Life Sciences & Medicine, Biomedical Engineering & Imaging Sciences, Department of Biomedical Engineering, King's College London, London, United Kingdom

Synopsis

Keywords: Safety, Safety, UHF-MRI, SAR, pTx design

Motivation: Specific absorption rate (SAR), a proxy measure for tissue heating, is affected by patient motion. SAR safety factors during MRI scanning are intentionally overconservative.

Goal(s): While designed to ensure patient safety, overconservativeness impedes the utility of scanning with parallel-transmit (pTx) 7T MRI. We aim to relieve pTx MRI from overconservativeness while maintaining patient safety.

Approach: We used deep learning to predict the location of hot-spots during head motion and applied them to a pTx design method which considers patient motion.

Results: We report that hot-spots are overcalculated almost 1.5-fold when the degree of motion is not included compared to when it is.

Impact: Deep learning-estimated local specific absorption rate (SAR) variations caused by patient motion may be combined with within-scan motion tracking and subject-specific SAR models to create personalized SAR supervision for patients who cannot remain still for high-performance scanning while ensuring patient-safety.

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