Low-field MR imaging for the assessment of therapy response in musculoskeletal infections.

Fifty-one patients with musculoskeletal infection were imaged by repeated MR imaging at ultra low-field and low-field strength. Soft-tissue infection, osteomyelitis, septic arthritis, and spondylitis were studied. The MR finding was scored according to the signal intensity (SI) on T2-weighted images (T2WI), and correlated with the values of serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and peripheral white blood cell (WBC) count. There was a positive correlation between the MR score and both CRP and ESR, but no correlation between MR score and WBC. The MR score between the follow-up studies decreased significantly in accordance with clinical reconstitution. The MR finding according to the SI on T2WIs corresponded better to disease activity than did the CRP or ESR.