Simultaneous 1H MRF / 23Na MRI in knee cartilage at 7 T

Motivation: Sodium MRI can provide tissue sodium concentration (TSC) and enable assessment of knee cartilage degradation. Goal(s): We aim to quantify TSC, proton density (PD) and 1H T1 and T2 in the knee from multinuclear simultaneous acquisition. Approach: We acquired 23Na-only FLORET and simultaneous 1H MRF/23Na MRI data in the knee of four healthy volunteers. We calculated TSC maps from both 23Na acquisitions for comparison, and PD, T1 and T2 maps from 1H MRF. Results: Mean TSC in patellar and femorotibial cartilage, and gastrocnemius muscle showed no significant differences between both sodium acquisitions. Mean TSC, PD, T1 and T2 values were within previously-reported range. Impact: We showed that a 3D simultaneous 1H MRF/23Na MRI acquisition at 7 T can provide reliable quantitative maps of TSC, PD, and 1H T1 and T2 relaxation times in cartilage.