Quantifying Quadriceps Myosteatosis via MRI

Each participant was screened for MRI safety before undergoing any MRI procedures. Participants were scanned while supine using a 3.0T MRI scanner (SIGNA Premier, GE Healthcare, Waukesha, WI) with a 30-channel array AIR anterior receive coil centered over the thigh. Participants underwent single-shot fast spin-echo sequence to orient and localize the mid-thigh and pelvis. A commercial confounder-corrected chemical shift encoded MRI (CSE MRI) method (IDEAL IQ, GE Healthcare) was used to generate PDFF maps of the thigh in both legs. The acquisition was performed using the following parameters: TR = 7.2 ms, 6 echoes in two echo trains of 3 echoes, 3° flip angle, 220 × 220 × 36 matrix, 46 × 46 cm² field of view, 6 mm slice thickness (35 (link)).
One trained researcher analyzed the PDFF images that matched quadriceps anatomy of the ultrasound brightness mode images in OsiriX (Pixmeo SARL, Geneva, Switzerland). The researcher measured RF cross-sectional area, whole-leg cross-sectional area, and RF PDFF for each participant. The researcher used circular, 1 cm² regions of interest (ROI) in the RF centrally to obtain RF PDFF values (see Figure 1). We used RF PDFF as the MRI-based measure of myosteatosis.