Optimization of Lipid Inversion with Hyperbolic Secant Adiabatic Pulses in Transient NOE at 7T

Motivation: In vivo lipid quantification in brain tissue is challenging due to limited uniform spin inversion with conventional adiabatic pulses, affecting transient NOE (tNOE) reliability. Goal(s): Optimize B1 amplitude of hyperbolic secant (HS) adiabatic pulses in tNOE to reduce magnetization transfer (MT) effects and improve lipid quantification repeatability. Approach: Validated optimized pulse parameters on a water phantom, then acquired repeatable tNOE maps in vivo, assessing white and gray matter contrast. Results: Optimized scanner voltage (305 V) produced high-quality tNOE contrast with minimal MT interference, showing CoVs of 1% for white and 3% for gray matter. Impact: This approach may improve lipid degeneration monitoring in neurodegenerative diseases like MS and Alzheimer's.