T1rho MRI at 3T of menisci in patients with acute anterior cruciate ligament (ACL) injury

Purpose: To explore the feasibility of T1rho mapping of menisci at 3T in discriminating between patients with acute anterior cruciate ligament (ACL) injury and healthy controls.

Materials and methods: Thirty-three subjects were included in the study and subdivided into two subgroups: 16 healthy controls (4 females, 12 males; mean age = 34.4 ± 10.2 years, age range 24-63 years), 17 patients with ACL injury (3 females, 14 males; mean age = 29.8 ± 10.8 years, age range 18-61 years). T1rho images from all subjects were acquired on a 3T MR scanner using a spin-lock-based 3D GRE sequence and computed for T1rho mapping. Clinical proton density (PD)-weighted fast spin echo (FSE) images in the sagittal (without fat saturation), axial, and coronal (fat-saturated) planes were also acquired for cartilage assessment using Whole-Organ MR Imaging Score (WORMS) grading. Mixed model two-way analysis of variance (ANOVA) was performed to determine whether there were any significant differences among subregional, compartmental, and whole structure T1rho values of meniscus between healthy controls and ACL-injured patients.

Results: Lateral posterior (29 ± 8 msec) and medial central (25 ± 7 msec) meniscus subregions in healthy controls had significantly lower T1rho values (P < 0.05) than the corresponding meniscus subregions in ACL-injured patients. Significantly lower meniscus T1rho values (P < 0.05) were also identified in lateral compartment in healthy controls (26 ± 6 msec) than that of ACL-injured patients (33 ± 4 msec). Subjects' total WORMS between healthy controls and ACL-injured patients had significant differences (P < 0.05).

Conclusions: These preliminary results indicate that T1rho mapping is possibly feasible in detecting meniscus degeneration and may be useful in distinguishing ACL-injured patients.