Contrast-enhanced dynamic and static MRI correlates with quantitative 99Tcm-labelled nanocolloid scintigraphy.: Study of early rheumatoid arthritis patients

Objective. The aim of this study was to evaluate the roles of contrast-enhanced dynamic and static magnetic resonance imaging (MRI) and quantitative Tc-99(m)-labelled nanocolloid (NC) scintigraphy in detecting wrist joint inflammation in early rheumatoid arthritis (RA) patients. Methods. Twenty-eight early RA patients (median symptom duration 5 months, range 1-12 months) underwent MRI, NC scintigraphy, laboratory and clinical examinations. Static wrist MRI scans were retrospectively scored for synovitis, bone oedema and erosions by two independent readers using the recently published rheumatoid arthritis MRI scoring system (RAMRIS). Twenty NC scans were analysed quantitatively by measuring maximum Tc-99(m)-NC uptake in three small areas of each wrist. From the same locations on the wrists, dynamic MRI gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) enhancement rates (E-rate) were measured. The average Tc-99(m)-NC uptake of the whole wrist region was also measured and average E-rates were calculated. Correlations between MRI and NC scintigraphy measurements were calculated. Correlations between imaging methods of the wrist and the global measures of inflammation (laboratory and clinical examinations) were also assessed. Results. Strong correlations emerged between maximal Tc-99(m)-NC uptake and MRI E-rates, reflecting similar performance of the methods in detecting local synovial inflammation. Tc-99(m)-NC uptake and MRI E-rate correlated with semiquantitative scoring of synovitis and bone oedema from static MRI scans. The erythrocyte sedimentation rate (ESR) correlated with MRI scores, E-rate and Tc-99(m)-NC uptake. No correlation between the clinical parameters and the imaging methods was detected. Inter-observer reliability for scoring synovial hypertrophy, bone oedema and bone erosions from static MR images were high (single-measure fixed-effects intra-class correlations 0.87, 0.93 and 0.91 respectively). Intra-observer reliability for E-rate and Tc-99(m)-NC measurements of 10 randomly picked scans was found to be high, with an intra-class correlation of 0.92; 95% confidence interval (CI) 0.84-0.96 and 0.99; 95% CI 0.98-1.00, respectively. Conclusions. Objective information about wrist joint inflammation can be obtained with contrast-enhanced dynamic MRI and quantitative Tc-99(m)-labelled NC scintigraphy. MRI also allows visualization and semiquantitative scoring of bone oedema and erosions of the wrist. Dynamic MRI and NC scintigraphy are safe and easy to perform, and they can be used in a long-term follow-up of rheumatoid patients.