Convincing Evidence For Magic Angle Less-Sensitive Quantitative T-1 Rho Imaging Of Articular Cartilage Using The 3d Ultrashort Echo Time Cones Adiabatic T-1 Rho (3d Ute Cones-Adiabt(1 Rho)) Sequence

Purpose To investigate the magic angle effect in three-dimensional ultrashort echo time Cones Adiabatic T-1 rho (3D UTE Cones-AdiabT(1 rho)) imaging of articular cartilage at 3T. Methods The magic angle effect was investigated by repeated 3D UTE Cones-AdiabT(1 rho) imaging of eight human patellar samples at five angular orientations ranging from 0 degrees to 90 degrees relative to the B-0 field. Cones continuous wave T-1 rho (Cones-CW-T-1 rho) and Cones-T2*sequences were also applied for comparison. Cones-AdiabT(1 rho), Cones-CW-T-1 rho and Cones-T2*values were measured for four regions of interest (ROIs) (10% superficial layer, 60% transitional layer, 30% radial layer, and a global ROI) for each sample at each orientation to evaluate their angular dependence.Results 3D UTE Cones-AdiabT(1 rho) values increased from the radial layer to the superficial layer for all angular orientations. The superficial layer showed the least angular dependence (around 4.4%), while the radial layer showed the strongest angular dependence (around 34.4%). Cones-AdiabT(1 rho) values showed much reduced magic angle effect compared to Cones-CW-T-1 rho and Cones-T2*values for all four ROIs. On average over eight patellae, Cones-AdiabT(1 rho) values increased by 27.2% (4.4% for superficial, 23.8% for transitional, and 34.4% for radial layers), Cones-CW-T-1 rho values increased by 76.9% (11.3% for superficial, 59.1% for transitional, and 117.8% for radial layers), and Cones-T2*values increased by 237.5% (87.9% for superficial, 262.9% for transitional, and 327.3% for radial layers) near the magic angle.Conclusions The 3D UTE Cones-AdiabT(1 rho) sequence is less sensitive to the magic angle effect in the evaluation of articular cartilage compared to Cones-T2*and Cones-CW-T-1 rho.