ABSTRACT
OBJECTIVE: Dynamic contrast-enhanced MRI of patients with rheumatoid arthritis has shown a decrease in the early enhancement rate (EER) of synovitis after treatment. The purpose of this work was to investigate the underlying changes. METHODS: 3D dynamic contrast-enhanced images were acquired from 13 patients before and 1-2 weeks after anti-TNF alpha treatment. The EER of the inflamed synovium was measured. The T1 relaxation time of the synovitis was calculated from images at different flip angles. The time course of the arrival of gadolinium at the radial artery was determined. The gadolinium enhancement of the inflamed synovium was modeled to calculate the fractional plasma volume (vp), the fractional extravascular, extracellular fluid volume (ve), and the volume transfer constant (Ktrans). Pre- and post-treatment values were compared and the dependence of the EER on each parameter was assessed. RESULTS: There was a decrease in the EER measured over 26 s after treatment (29%, p = 0.002). Reductions in T1 (12%, p = 0.001), Ktrans (31%, p = 0.002), and vp (43%, p = 0.01) contributed to this; however, the EER was relatively insensitive to changes in ve. CONCLUSIONS: The decrease in EER after anti-TNF alpha treatment is largely caused by reductions in the volume transfer constant Ktrans, the fractional plasma volume vp, and the T1 relaxation time. Only the contributions from Ktrans and vp directly reflect synovial vascularity.
Subject(s)
Antirheumatic Agents/therapeutic use , Arthritis, Rheumatoid/drug therapy , Arthritis, Rheumatoid/pathology , Magnetic Resonance Imaging/methods , Contrast Media , Female , Heterocyclic Compounds , Humans , Imaging, Three-Dimensional , Male , Middle Aged , Organometallic Compounds , Sensitivity and Specificity , Statistics, Nonparametric , Synovitis/pathology , Tumor Necrosis Factor-alpha/antagonists & inhibitorsABSTRACT
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.
Subject(s)
Antirheumatic Agents/therapeutic use , Arthritis, Rheumatoid/pathology , Contrast Media , Image Enhancement/methods , Magnetic Resonance Imaging/methods , Metacarpophalangeal Joint/pathology , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Wrist Joint/pathology , Arthritis, Rheumatoid/drug therapy , Bone Marrow/pathology , Gadolinium , Heterocyclic Compounds , Humans , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Metacarpophalangeal Joint/drug effects , Models, Biological , Organometallic Compounds , Reproducibility of Results , Synovial Membrane/drug effects , Synovial Membrane/pathology , Synovitis/drug therapy , Synovitis/pathology , Treatment Outcome , Wrist Joint/drug effectsABSTRACT
The cervical spine is a common focus of destruction from rheumatoid arthritis, second only to the metacarpophalangeal joints. Joint, bone and ligament damage in the cervical spine leads to subluxations which can cause cervical cord compression resulting in paralysis and even sudden death. Because many patients with significant subluxations are asymptomatic, the radiologist plays a key role in recognizing the clinically important clues to instability on plain radiographs of the cervical spine-often difficult in rheumatoid arthritis when the bony landmarks are osteoporotic or eroded. This review focuses on the signs of instability on plain radiographs of the cervical spine, using diagrams and clinical examples to illustrate methods of identifying significant subluxations in rheumatoid arthritis.