Application Of MRI T2-star-mapping Imaging For Cartilage Quantitative Analysis In The Diagnosis Of Knee Osteoarthritis

Objective To investigate the clinical significance of MRI T2-star-mapping imaging for cartilage quantitative analysis in the diagnosis of knee osteoarthritis.Methods Twenty-two cases of normal volunteers(aged 20 to 25, all females) were selected as the control group consisting of 20 knees; 60 cases of knees, including 20 cases of patients with clinically diagnosed mild OA, 20 cases with moderate OA and 20 cases with severe OA, were taken as patient groups. Using GE 3.0T MRI scanner, the T2-star-mapping imaging of knees was performed to obtain the T2* values of articular surface of medial femoral condyle, articular surface of lateral femoral condyle, articular surface of medial tibial condyle, articular surface of lateral tibial condyle, and cartilage of patella; the inter-group differences in T2* values were then compared. The ex-vivo cartilage specimens were obtained after unicompartmental knee arthroplasty and total knee replacement, and the differences in T2* values at all grades were compared after Collins pathological grading.Results1. The mean T2* value of articular cartilage was(21.74±3.82)ms in the normal control group; the mean T2* value of articular cartilage was(27.55±5.48)ms in the mild OA group; the mean T2* value of articular cartilage was(35.01±8.83)ms in the moderate OA group; mean T2* value of articular cartilage was(41.14±14.20)ms in the severe OA group.2. Compared with the T2* value of articular cartilage in the normal control group, the T2* values of articular cartilage in the mild OA group, the moderate OA group and the severe OA group were significantly increased, suggesting statistically significant differences(P<0.01).3. Compared with the normal control group, the T2* values of cartilages at these five sites were increased in all OA groups; as the articular cartilage degeneration was aggravated, corresponding T2* values were increased, indicating a statistically significant difference(P<0.05).4.In comparison of T2* values of cartilage degeneration with Collins pathological grading, the corresponding T2* values were gradually increased with the Collins pathological grades of cartilage degeneration; the T2* values were significantly elevated with the level of cartilage degeneration; the differences between different grades were statistically significant.Conclusions1. As the articular cartilage degeneration is aggravated, corresponding T2* values are increased. MRI T2-star-mapping imaging for cartilage quantitative analysis can be used as a check method of early diagnosis of OA.2. The corresponding T2* values are gradually increased with the Collins pathological grades of cartilage degeneration, and the T2* values are significantly elevated with the level of cartilage degeneration. The changes in T2* values of articular cartilages provide an important examination method for the diagnosis of OA.3. Through quantitative analysis of the changes in internal tissue components of articular cartilages at the level of microstructure, MRI T2-star-mapping imaging for cartilage quantitative analysis, as a new MRI physiological imaging technique for cartilages, can contribute to the early identification of articular cartilage lesions before the onset of morphological changes in articular cartilage. Therefore, it has high clinical value in the diagnosis and monitoring of early articular cartilage injuries.