Multi-vendor multi-site T_1ρ and T₂ quantification of knee cartilage

Objective: To develop 3D T_1ρ and T₂ imaging based on the same sequence structure on MR systems from multiple vendors, and to evaluate intra-site repeatability and inter-site inter-vendor reproducibility of T_1ρ and T₂ measurements of knee cartilage. Methods: 3D magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (3D MAPSS) were implemented on MR systems from Siemens, GE and Philips. Phantom and human subject data were collected at four sites using 3T MR systems from the three vendors with harmonized protocols. Phantom data were collected by means of different positioning of the coil. Volunteers were scanned and rescanned after repositioning. Two traveling volunteers were scanned at all sites. Data were transferred to one site for centralized processing. Results: Intra-site average coefficient of variations (CVs) ranged from 1.09% to 3.05% for T_1ρ and 1.78–3.30% for T₂ in phantoms, and 1.60–3.93% for T_1ρ and 1.44–4.08% for T₂ in volunteers. Inter-site average CVs were 5.23% and 6.45% for MAPSS T_1ρ and T₂, respectively in phantoms, and 8.14% and 10.06% for MAPSS T_1ρ and T₂, respectively, In volunteers. Conclusion: This study showed promising results of multi-site, multi-vendor reproducibility of T_1ρ and T₂ values in knee cartilage. These quantitative measures may be applied in large-scale multi-site, multi-vendor trials with controlled sequence structure and scan parameters and centralized data processing.