T2 mapping and dGEMRIC after autologous chondrocyte implantation with a fibrin-based scaffold in the knee: Preliminary results

Objective

To assess repair tissue (RT) after the implantation of BioCart™II, an autologous chondrocyte implantation (ACI) technique with a fibrin-hyaluronan polymer as scaffold. T2 mapping and delayed Gadolinium Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) were used to gain first data on the biochemical properties of BioCart™II RT in vivo.

Methods

T2 mapping and dGEMRIC were performed at 3 T in five patients (six knee joints) who had undergone ACI 15-27 months before. T2 maps were obtained using a pixel wise, mono-exponential non-negative least squares fit analysis. For quantitative T1 mapping a dual flip angle 3D GRE sequence was used and T1 maps were calculated pre- and post-contrast using IDL software. Subsequent region of interest analysis was carried out in comparison with morphologic MRI.

Results

A spatial variation of T2 values in both hyaline, normal cartilage (NC) and RT was found. Mean RT T2 values and mean NC T2 values did not differ significantly. Relative T2 values were calculated from global RT and NC T2 and showed a small range (0.84-1.07). The relative delta relaxation rates (rΔR1) obtained from the T1 maps had a wider range (0.77-4.91).

Conclusion

T2 mapping and dGEMRIC provided complementary information on the biochemical properties of the repair tissue. BioCart™II apparently can provide RT similar to hyaline articular cartilage and may become a less-invasive alternative to ACI with a periosteal flap.