ABSTRACT

The PhD dissertation, from H:S Frederiksberg Hospital, is based upon four studies evaluating the use of Doppler ultrasound (US) in the evaluation of inflammation in rheumatoid arthritis (RA). The resistive index (RI) and colour fraction are evaluated qualitatively and quantitatively in the estimation of inflammation in RA patients in relation to treatment and by comparison to MRI and healthy subjects.

In study I, the colour fraction and RI were used in detecting a treatment response in a longitudinal study during systemic treatment with the TNF α blocking agent Etanercept. A target joint was followed and both parameters showed statistically significant changes that were paralleled by clinical changes after two weeks of treatment. After one year, there was still a significant improvement in the clinical parameters but not in the colour fraction or RI, though the latter showed a tendency towards an increased peripheral resistance.

In study II the colour fraction and RI were used in detecting a treatment response before and four weeks after intra-articular treatment with glucocorticosteroids.

At one-month follow-up, a significant decrease in the colour fraction and an increase in RI were seen, indicating a diminished flow to the synovium. Both the colour fraction and the RI values corresponded to the clinical evaluation and to the subjective effect of the treatment.

In study III, the wrist and finger joints of the symptomatic hand of the RA patients were examined by both ultrasound and MRI, thus examining both symptomatic and asymptomatic joints for comparison. We found a highly significant association between the Doppler parameters and the post-contrast MRI scores. The RI had the best association to the degree of both tender and swollen joints. Both imaging modalities depicted signs of inflammation in clinically unaffected joints

In study IV, healthy subject were examined for signs of Doppler activity. RI and/or colour fraction could be detected most commonly in the wrist and more rarely in the metacarpal joints and hardly ever in the proximal interphalangeal joints. In the joints recommended by the ACR to be evaluated in RA, we found no erosive changes indicating that the presence of erosions by ultrasound are signs of pathology.

In conclusion, the colour fraction and the RI are able to detect a treatment response both after local and systemic treatment and the changes in both parameters are paralleled by changes in the clinical evaluation.

As Doppler findings may be found in healthy volunteers they cannot be used for diagnostic purposes until cut-off levels for the colour fraction and the RI have been determined.