T(1ρ) and T(2) quantitative magnetic resonance imaging analysis of cartilage regeneration following microfracture and mosaicplasty cartilage resurfacing procedures

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