Longitudinal evaluation of cartilage composition of matrix-associated autologous chondrocyte transplants with 3-T delayed gadolinium-enhanced MRI of cartilage

Abstract

OBJECTIVE. The purposes of this study were to use delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) to evaluate the zonal distribution of glycosaminoglycans (GAGs) in normal cartilage and repair tissue and to use 3-T MRI to monitor the GAG content in matrix-associated autologous chondrocyte transplants. SUBJECTS AND METHODS. Fifteen patients who underwent matrix-associated autologous chondrocyte transplantation in the knee joint underwent MRI at baseline and 3-T follow-up MRI 1 year later. Total and zonal changes in longitudinal relaxivity (δR1) and relative δR1 were calculated for repair tissue and normal hyaline cartilage and compared by use of analysis of variance. RESULTS. There was a significant difference between the mean δR1 of repair tissue and that of reference cartilage at baseline and follow-up (p < 0.001). There was a significant increase in δR1 value and a decrease in GAG content from the deep layer to the superficial layer in the reference cartilage and almost no variation and significantly higher values for the repair tissue at both examinations. At 1-year follow-up imaging, there was a 22.7% decrease in δR1 value in the deep zone of the transplant. CONCLUSION. T1 mapping with dGEMRIC at 3 T shows the zonal structure of normal hyaline cartilage, highly reduced zonal variations in repair tissue, and a tendency toward an increase in global and zonal GAG content 1 year after transplantation. © American Roentgen Ray Society.