Variability of CubeQuant T1ρ, quantitative DESS T2, and cones sodium MRI in knee cartilage

Objective: To measure the variability of T-1 rho relaxation times using CubeQuant, T-2 relaxation times using quantitative double echo in steady state (DESS), and normalized sodium signals using 3D cones sodium magnetic resonance imaging (MRI) of knee cartilage in vivo at 3 T. Design: Eight healthy subjects were scanned at 3 T at baseline, 1 day, 5 months, and 1 year. Ten regions of interest (ROIs) of knee cartilage were segmented in the medial and lateral compartments of each subject's knee. T-1 rho and T-2 relaxation times and normalized sodium signals were measured and the root-mean-square coefficient of variation (CVRMS) was calculated. Intra-subject variability was measured over short, moderate and long-term, as well as intra-observer and inter-observer variability. Results: The average intra-subject CVRMS measurements over short, moderate, and long-term time periods were 4.6%, 6.1%, and 6.0% for the T-1 rho measurements, 6.4%, 9.3%, and 10.7% for the T-2 measurements and 11.3%, 11.6%, and 12.9% for the sodium measurements, respectively. The average CVRMS measurements for intra-observer and inter-observer segmentation were 3.8% and 5.7% for the T-1 rho measurements, 4.7% and 6.7% for the T-2 measurements, and 8.1% and 11.4% for the sodium measurements, respectively. Conclusions: These CVRMS measurements are substantially lower than previously measured changes expected in patients with advanced osteoarthritis compared to healthy volunteers, suggesting that CubeQuant T-1 rho, quantitative DESS T-2 and 3D cones sodium measurements are sufficiently sensitive for in vivo cartilage studies. (C) 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.