Pharmacokinetic modeling of dynamic contrast‐enhanced MRI of the hand and wrist in rheumatoid arthritis and the response to anti‐tumor necrosis factor‐α therapy

Dynamic contrast-enhanced MRI (DCE-MRI) of the hand and wrist was performed in 11 patients with rheumatoid arthritis twice before and once 2 weeks after treatment with anti-tumor necrosis factor (TNF)-alpha therapy. A rapid, T1-weighted 3D spoiled gradient echo (SPGR) sequence was used for the dynamic imaging. T1 estimation was performed using similar images obtained at different flip angles. The relative radiofrequency field was estimated from the known T1 of the periarticular fatty marrow. The arterial input function (AIF) was measured at each examination, and normalized to the expected plasma concentration to reduce partial volume effects. Synovial enhancement was modeled to yield values for Ktrans, ve, and vp. Ktrans and ve showed good reproducibility. There was a significant decrease of about 20% in Ktrans after 2 weeks of treatment. This study demonstrates the potential of DCE-MRI and pharmacokinetic modeling to study early changes in inflammatory activity in rheumatoid arthritis following treatment.