In vivo T1rho quantitative assessment of knee cartilage after anterior cruciate ligament injury using 3 Tesla magnetic resonance imaging.

OBJECTIVE: The aims of this study were to evaluate the spatial distribution of cartilage structure in controls and patients, and to quantitatively assess the cartilage overlying bone marrow edema-like lesion (BMEL) and within defined cartilage compartments in knees with anterior cruciate ligament (ACL) tears using T1rho mapping technique at 3 T magnetic resonance imaging.

MATERIALS AND METHODS: The knee joints of 15 healthy controls (4 women, 11 men, mean age = 30.1 year) and 16 patients with ACL tear (5 women, 11 men, mean age = 32.5 years) who showed BMEL was studied using a 3 T GE MR scanner and a quadrature knee coil. The imaging protocol included sequences for cartilage morphology and 3D quantitative T1rho mapping. Lateral femoral condyle and medial femoral condyles compartments were partitioned into anterior and posterior nonweight-bearing (ant-nwb and postnwb) portions and weight-bearing (wb) portions in all subjects. In patients only, cartilage overlying BMEL and surrounding cartilage portions were also defined. T1rho values were quantified in cartilage overlying BMEL and surrounding compartments and in each defined compartment of the ACL-injured knees, and compared with controls.

RESULTS: Significantly elevated T1rho values were found in the femoral nonweight-bearing (nwb) portions when compared with weight-bearing (wb) portions both in patients and controls. Significantly increased T1rho values were found in cartilage overlying BMEL when compared with surrounding cartilage at the lateral tibia (LT), but no difference was found in the lateral femoral condyle.

CONCLUSION: T1rho mapping technique provides tools to quantitatively evaluate the cartilage matrix overlying BMEL in patients with ACL injuries. Cartilage abnormalities are already present following initial ACL injuries over the lateral tibia. Quantitative MRI can allow critical evaluation of medical and surgical treatments for ligament and degenerative conditions of the knee.