Background Recently, the gradient-echo-based T1-delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) has been developed for the detection of proteoglycan content in cartilage; moreover, multi-echo and spin-echo T2-mapping has become increasingly popular for the assessment of cartilage hydration and collagen microstructure. Current Magnetic Resonance Imaging (MRI)-studies conclude a link between dGEMRIC and T2 and early changes of cartilage in inflammatory diseases. Yet further validation studies on their diagnostic value in inflammatory diseases are needed.
Objectives To investigate the correlation between morphological and biochemical alterations in the cartilage of patients with Rheumatoid Arthritis (RA) by high-resolution 3Tesla-MRI.
Methods 29 RA-patients received a 3Tesla-MRI scan of the 2nd and 3rd metacarpophalangeal (MCP) joint of the dominant hand with 2 small-diameter surface coils designed for high-resolution imaging of cartilage (0.26×0.26×105mm voxel size; Verio Siemens Healthcare, Erlangen, Germany). T2-mapping and dGEMRIC were done. T2 and T1 relaxation times were obtained using a region-of-interest (ROI) evaluation. MCP heads and bases were scored semiquantitatively for synovitis, bone marrow edema (BME) and bone erosion (BE) using the RA MRI scoring (RAMRIS) system; joint space and cartilage thickness were measured perpendicular to the joint plane in all 3 joint regions (fig. 1a).
Results For correlation analysis means of real and total joint spaces (RJS, TJS), RAMRIS-subscores, and ROIs of dGEMRIC- and T2-evaluations were used (fig. 1a: source data acquisition, fig. 1b: correlation analysis). Early changes of cartilage such as BME and synovitis in RAMRIS as compared to dGEMRIC were correlated negative (p=0.029; p=0.003); likewise, BME and synovitis showed positive correlation (p=0.013; p=0.015) in T2. In contrast, changes of periarticular structure occurring at later stages of the disease such as BE did not correlate with dGEMRIC (p=0.704) and weakly with T2 (p=0.026). All joint space subanalyses of MCP3 despite RJS correlated with dGEMRIC and T2 mainly in medial region (TJS p=0.017; TCT p=0.020; CT p=0.018). Additionally, in dGEMRIC MCP2 and RJS correlated in ulnar side (p=0.001).
Conclusions dGEMRIC and T2-mapping in high-resolution MRI enable exact detection of very early inflammatory changes in cartilage known to precede RA-typical periarticular bone damage. This is important both for early discovery of damages, adequate therapy decisions and -monitoring; this may also influence the development of future anti-inflammatory drugs. Additional studies on mechanical influences on cartilage are needed to further evaluate the mechanisms of joint space alterations.
Disclosure of Interest None Declared