Volumetric multislice gag CEST imaging of articular cartilage: Optimization and comparison with T1rho.

Purpose To develop and optimize a multislice glycosaminoglycan (GAG) chemical exchange saturation transfer (GagCEST) sequence for volumetric imaging of articular cartilage, and to validate the sequence against T_1ρ relaxation times in whole joint imaging of tibiotalar cartilage. Methods Ex vivo experiments were used to observe the effect of the number of partitions and shot TR on signal-to-noise ratio and measured GagCEST_asym. GagCEST imaging of the entire tibiotalar joint was also performed on 10 healthy subjects. The measured GagCEST_asym was compared and correlated with T_1ρ relaxation times. Results Ex vivo studies showed a higher average GagCEST_asym from articular cartilage on multislice acquisitions acquired with two or more partitions than observed with a single-slice acquisition. In healthy human subjects, an average GagCEST_asym of 8.8 ± 0.7% was observed. A coefficient of variation of GagCEST_asym across slices of less than 15% was seen for all subjects. Across subjects, a Pearson correlation coefficient of −0.58 was observed between the measured gagCEST_asym and T_1ρ relaxation times. Conclusions We demonstrated the feasibility and optimization of multislice GagCEST mapping of articular cartilage. Volumetric analysis and decreased scan times will help to advance the clinical utility of GagCEST imaging of articular cartilage. Magn Reson Med 77:1134-1141, 2017. © 2016 International Society for Magnetic Resonance in Medicine [ABSTRACT FROM AUTHOR]