[Modification of longitudinal relaxation time (T1) as a biomarker of patellar cartilage degeneration].

OBJECTIVES To study the viability of longitudinal relaxation time (T1) of patellar cartilage as a biomarker of the degree of degeneration. MATERIAL AND METHODS We included 15 subjects classified into three groups according to clinical criteria (pain, functional limitation, and duration of symptoms) and imaging criteria as follows: (a) normal (3 men, 2 women; age 30+/-14 years), (b) with initial degeneration of the patellar cartilage (3 men, 2 women; age 30+/-6 years), or (c) with advanced degeneration (3 men, 2 women; age 57+/-10 years). All underwent MRI examination using special echo-gradient sequences to segment the cartilage and calculate the T1 maps. We selected the entire cartilage and the regions of interest classified according to clinical and imaging criteria as normal, initial degeneration, and advanced degeneration. The T1 values of the cartilage were obtained pixel by pixel and were calculated as the mean for the entire cartilage or by subregions (normal, initial, advanced). Differences between groups for the entire cartilage and the regions were analyzed using Student-Newman-Keuls post-hoc ANOVA. Reproducibility was evaluated using the coefficient of variance. RESULTS No significant differences in the overall analysis of the entire cartilage were found between the three groups (normal: 1003+/-172 ms, initial: 1064+/-124 ms, advanced: 1041+/-308 ms, p=0.665). However, the analysis by regions revealed significant differences (normal: 908+/-53 ms, initial degeneration: 1057+/-157 ms, advanced degeneration: 1133+/-116 ms, p=0.029). The reproducibility analysis found variations of 1.3% for the overall calculation, 3.7% for the regional calculation, and 8.2% for the acquisition. CONCLUSION In this preliminary study, calculating the T1 of the cartilage enabled regions with different degrees of degeneration to be differentiated.