T2 and T2* mapping in patients after matrix-associated autologous chondrocyte transplantation: initial results on clinical use with 3.0-Tesla MRI
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To use T2 and T2* mapping in patients after matrix-associated autologous chondrocyte transplantation (MACT) of the knee, and to compare and correlate both methodologies.
3.0-Tesla MRI was performed on 30 patients (34.6 ± 9.9 years) with a follow-up period of 28.1 ± 18.8 months after MACT. Multi-echo, spin-echo-based T2 mapping using six echoes and gradient-echo-based T2* mapping using six echoes were prepared. T2 and T2* maps were obtained using a pixel-wise, mono-exponential, non-negative least-squares fit analysis. Region-of-interest analysis was performed for mean (full-thickness) as well as deep and superficial aspects of the cartilage repair tissue and control cartilage sites.
Mean T2 values (ms) were comparable for the control cartilage (53.4 ± 11.7) and the repair tissue (55.5 ± 11.6) (p > 0.05). Mean T2* values (ms) for control cartilage (30.9 ± 6.6) were significantly higher than those of the repair tissue (24.5 ± 8.1) (p < 0.001). Zonal stratification was more pronounced for T2* than for T2. The correlation between T2 and T2* was highly significant (p < 0.001), with a Pearson coefficient between 0.276 and 0.433.
T2 and T2* relaxation time measurements in the evaluation of cartilage repair tissue and its zonal variation show promising results, although the properties visualised by T2 and T2* may differ.
KeywordsT2 T2* MRI 3.0 Tesla Cartilage repair
Timothy Hughes is an employee of Siemens Medical Solutions. Funding for this study was provided by the project “Vienna Advanced Clinical Imaging Center” (VIACLIC), within the “Vienna Spots Of Excellence” program; a collaboration of the Medical University of Vienna and Siemens Austria.
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