MRI OF THE KNEE IN RHEUMATOID-ARTHRITIS - GD-DTPA PERFUSION DYNAMICS

Objective: Seventeen knees in 13 patients with rheumatoid arthritis (R A) were studied with MRI to clarify the dynamics of Gd-DTPA administer ed intravenously and to determine an optimal imaging time. Materials a nd Methods: Dynamic gradient recalled echo imaging with bolus intraven ous injection of Gd-DTPA was performed following unenhanced T1- and T2 -weighted SE imaging. Late-phase SE or serial gradient recalled echo i mages were obtained following dynamic study. Results: There was rapid enhancement of synovium with maximal enhancement ratio of 96-499% (mea n 214 +/- 111%) with T(max) ranging from 120 to 660 s (mean 253 s). Th e synovial enhancement persisted over 80% of the peak enhancement for 6-27 min (average 12 min) with eventual enhancement of joint effusion from the periphery to the center beginning at 6 min to 8 min, 20 s aft er contrast medium injection. Complete enhancement of joint effusion w as noted in four joints at 24-86 min. Conclusion: We conclude that enh ancement of synovium in patients with RA is a time-dependent phenomeno n, and an optimal imaging time would be within 5 min following contras t medium administration.