Introduction:

Osteoarthritis of the knee (KOA) affects millions of people worldwide. Advanced KOA is successfully treated with a knee replacement. However, conservative treatment is still the main therapy method, even though there may be many mild to moderate osteoarthritis have symptoms. It is known that cartilage composition and morphological changes are the main manifestations of early osteoarthritis. There are some semi-quantitative scoring systems to assess the articular cartilage, but each of these systems has its own strengths and weaknesses^[1]. The aim of this study was to quantitative measurements of the cartilage volume (CV), thickness (CT) and T2 relaxation times in patients with symptomatic mild to moderate KOA by using T2 mapping in 3 T MR.

Methods:

The study included 31 subjects with KOA which were divided into a mild OA group (Kellgren-Lawrence grade 1 and 2; n = 17) and a moderate OA group (Kellgren-Lawrence grade 3; n = 14). The Knee joint of each subject was examined using a 3 Tesla (3T) MR scanner (MAGNETOM Skyra,Siemens Healthcare, Erlangen, Germany). An eight-channel knee coil was used for all the MR knee scannningin a supine position and feet first mode. A 2D multi-echo sequence was used for the T2mapping. A 3-dimensional double-echo steady-state (3D-DESS) sequence was used for high-resolution morphologic imaging. The knee joint cartilage was automatically segmented using a prototypic software (MR Chondral Health, version 2.1, Siemens Healthcare, Erlangen, Germany). Cartilage volume, thickness and T2 relaxation times of patella, trochlear of femur, medial posterior/cental/anterior of femur (MFp, MFc, MFa), lateral posterior/cental/anterior of femur (LFp, LFc, LFa), medial tibial (MT) and lateral tibial (LT) were evaluated. The independent samples t-test were performed to evaluate the significance of the inter-group difference.

Results:

Compared with the mild, the moderate OA patients exhibited decreased CV and CT with the growth of K-L grade, and the T2 value increased with the growth of K-L grade. Specifically, the CV and CT of patella, MFc, MFa, MT and CT of trochlear of femur in the moderate OA group were significantly lower than those in mild group (P < 0.05), and the T2 value of patella, MFc, MFa, LFa and MT in the moderate OA group were significantly higher than those in mild group (P < 0.05). There were no significant difference in CV, CT and T2 value in other regions.

Conclusion:

Both biochemical imaging and morphologic examinations were sensitive to study the mild to moderate KOA. We also found that the automatic cartilage segmentation software can quickly and quantitative measurements of the cartilage volume, thickness and T2 value, which was beneficial to the longitudinal follow-up study for the mild to moderate KOA.

Acknowledgements

No acknowledgement found.

References

1.Juras V , Szomolanyi P , Schreiner M M , et al. Reproducibility of an Automated Quantitative MRI Assessment of Low-Grade Knee Articular Cartilage Lesions[J]. Cartilage, 2020:1947603520961165.