Importance of timing of post-contrast MRI in rheumatoid arthritis: what happens during the first 60 minutes after IV gadolinium-DTPA?

Abstract

Background-Volumes of inflamed synovial membrane determined by magnetic resonance imaging (MRI) are closely related to histopathological synovitis and may predict erosive progression in rheumatoid arthritis (RA). However, after IV injection, leakage of MRI contrast from the synovium gradually compromises the diVerentiation of synovium from joint fluid. Objective-To determine the time period after IV MRI contrast (gadolinium-DTPA (Gd)) injection in which synovial membrane volume determination is reliable. Methods-MRI of five RA knees with clinical synovitis was carried out, with axial, T 1 weighted, spin echo images before IV Gd injection and every 1.75 minutes for 60 minutes post-Gd. By a semiautomated "signal enhancement threshold" method, including voxels with >35% or >45% relative post-Gd enhancement, synovial membrane volumes were estimated at each time point. At 4.25 minutes post-Gd, volumes were also determined by a more accurate but time consuming "manual method". Results-The initially observed synoviumeVusion borderline remained clearly visible, and on the same location, within at least the initial 11 minutes post-Gd (that is, within the normal time frame of post-Gd imaging in RA) but started blurring and moving centripetally thereafter. Compared with volumes at all other time points, synovial membrane volumes at 0.75 and 2.50 minutes post-Gd were significantly lower (Wilcoxon-Pratt), suggesting that some synovial membrane areas had not yet exceeded the enhancement threshold. Thereafter, the measured volumes remained practically unchanged. Conclusion-This study suggests that MR image acquisition in arthritic knee joints should be performed within the initial approximately 10 minutes after gadolinium contrast injection to achieve the most accurate distinction between synovium and joint fluid but that small time variations are not of major importance to the measured synovial membrane volumes.

Maximum intensity projection as a tool to diagnose early rheumatoid arthritis

“…Recently, there have been several reports about the usefulness of contrast-enhanced MRI for early diagnosis of RA [4,6,8,10,12,16,18,19,22]. In a study by McQueen et al [12] MRI revealed carpal erosions in 45% and synovitis in 70% of a group of RA patients at 4 months from the onset of symptoms, only 15% of whom had erosions on plain radiographs [11].…”

MR Imaging Assessment of Arthritis of the Knee

“…38 When not performing dynamic gadolinium imaging, images should be acquired within 10 minutes of gadolinium injection because contrast will diffuse into the joint fluid, thus limiting the reliable distinction of synovium from effusion. 8 Besides the common features of infectious or inflammatory arthropathies already described, additional features that may suggest RA include the following. (1) Rice bodies consist of sloughed fibrinous material and necrotic debris.…”

“…7 The true extent of synovitis should be assessed within 10 minutes following the administration of intravenous contrast, because rapid diffusion of gadolinium into the adjacent effusion may preclude distinction of synovitis adjacent to the effusion later. 8 The signal characteristics of the thickened synovium also should be assessed for patterns that deviate from the typical intermediate T1 and high T2 signal of acute synovitis. Synovitis that is low in signal on T2-weighted images is usually an indication of either increased collagen in chronic synovitis or hemosiderin in the synovium in entities such as pigmented villonodular synovitis (PVNS) Fig.…”

The Role of Magnetic Resonance Imaging in the Early Diagnosis of Rheumatoid Arthritis

“…37 The initial period of 10 minutes after administration of contrast has been suggested as optimal time for imaging of the knee joint. 38 Other reports suggest that the optimal timing for imaging of the knee may be even as early as the initial period of 5 to 6 minutes. 39,40 The use of contrast-enhanced MRI in evaluation of RA is supported by several studies.…”