T1ρ and T2 Quantitative Magnetic Resonance Imaging Analysis of Cartilage Regeneration Following Microfracture and Mosaicplasty Cartilage Resurfacing Procedures

Purpose: To examine T-1 rho (T1rho) and T-2 quantitative magnetic resonance imaging (MRI) in evaluating cartilage regeneration following microfracture (MFx) and mosaicplasty (MOS) cartilage resurfacing procedures. Materials and Methods: Eighteen patients underwent MFx and eight patients underwent MOS to treat symptomatic focal cartilage defects. Quantitative T-1 rho and T-2 maps were acquired at 3-6 months and 1 year after surgery. The area of resurfacing was identified, and T-1 rho and T-2 values for the regenerated tissue (RT) and normal cartilage (NC) were acquired. RT/NC ratios were calculated to standardize absolute T-1 rho and T-2 values. Data were prospective, cross-sectional, and nonrandomized. Results: T-1 rho and T-2 showed good reanalysis reproducibility for RT and NC. Significant differences between RT and NC were present following MFx at 3-6 months for T-1 rho and T-2 values as well as following MOS at 3-6 months and 1 year for T-1 rho values. Following MFx, the T-2 RT/NC ratio was significantly different between 3-6 months and 1 year (P = 0.02), while the T-1 rho RT/NC ratio approached significance (P = 0.07). Following MOS, the T-1 rho and T-2 RT/NC ratios were not significantly different between the two timepoints. Conclusion: T-1 rho and T-2 MRI are complementary and reproducible methods for quantitatively and noninvasively monitoring regeneration of RT following MFx and MOS.