Improved Sodium MRI of the Human Knee with Projection Acquisition in the Steady State at 4.7 Tesla

Alexander Watts¹, Robert Stobbe¹, Adrian Tsang¹, Christian Beaulieu¹

Sodium MRI of knee cartilage is a possible diagnostic method for osteoarthritis, but low signal strength in vivo results in poor quality images. A steady state approach (shorter TR, longer excitation pulse widths) to 3D twisted projection image acquisition may improve sodium SNR by increased averaging over a constant scan time and SAR of 6 W/kg. Simulations predicted a 42% increase in SNR for steady state over fully relaxed parameters while a 26+/-5% increase was determined experimentally for sodium in human knee cartilage (n=9). Partial volume effects with synovial fluid and/or relaxation parameter differences may be responsible for this disagreement.