Comparison Of MR T1 Mapping And T2 Mapping In Early Chondromalacia Patellae

Objective: To analyse and compare the value of T1 mapping and T2 mapping in assessing early chondromalacia patellae(CP).Methods: This study comprised 58 knees of 32 patients as experimental group and 62 knees of 31 healthy volunteers as control group. T1 mapping and T2 mapping of patellar cartilage were performed in these subjects at 3.0T magnet. Manifestations of patellar cartilage on T1 maps and T2 maps were observed, and T1 values and T2 values of patellar cartilage were measured. Consistency of T1 mapping and T2 mapping was evaluated by Kappa-test. Wilcoxon rank sum test was performed to compare the differences of T1 values and T2 values between the two groups. Correlations between T1 values and T2 values of the two groups were studied by using Spearman rank correlation.Results: Of all the patellar cartilage in experimental group, 44 showed abnormal colour gradation both in T1 maps and T2 maps which represented high T1 or T2 values, 3 showed abnormal colour gradation only in T1 maps, 3 showed abnormal colour gradation only in T2 maps, the remaining 8 ones showed homogeneous colour gradation both in T1 maps and T2 maps. In control group, 1 patellar cartilage showed abnormal colour gradation both in T1 maps and T2 maps, 4 showed abnormal colour gradation only in T1 maps, 5 showed abnormal colour gradation only in T2 maps, the remaining 52 ones showed homogeneous colour gradation both in T1 maps and T2 maps. Kappa-test shows that there are strong consistency between T1 mapping and T2 mapping for detecting early stage chondromalacia patellae(Kappa=0.746, P=0.000). The median T1 values of experimental group were 1502.9ms(range 1388.7~1586.4ms) and 1385.5ms(range 1294.7~1510.0ms) respectively, and there was a significant difference between the two groups(P<0.001). The median T2 values of experimental group and control group were 46.2ms(range 43.8~50.0ms) and 43.1ms(range 39.7~46.7ms) respectively, and there was a significant difference between the two groups either(P=0.001). Positive correlations between T1 values and T2 values of the two groups were observed both in experimental group(r=0.615, P<0.001) and control group(r=0.657, P<0.001).Conclusions: T1 mapping and T2 mapping are feasible to detect early CP by observing either the changes of colour gradation or the changes of T1 values and T2 values of patellar cartilage, besides, there is high degree of consistency between T1 mapping and T2 mapping in diagnosis early CP..