OBJECTIVE To evaluate ultrasonographic methods, including the Doppler technique, as measures of synovial inflammation in finger joints of patients with rheumatoid arthritis.
METHODS Ultrasonography was performed with a high frequency transducer (13 MHz).
Evaluation of the sonographic data was conducted by two independent observers and included measurement of synovial area and thickness (grey tone ultrasound), vascularisation (power/colour Doppler), and indices of the intra- and extrasynovial arterial flow (spectral Doppler). The flow pattern was estimated by the indices of pulsatility (PI) and resistance (RI).
RESULTS The sonographic measurements of joint space were reproducible with intraobserver, intraclass correlation coefficients (ICC) 0.82–0.97 (p<0.0001) and interobserver ICC 0.81 (p<0.0001). The mean (SD) fraction of the synovium vascularised in the patients was 0.15 (0.15). The synovial blood flow was characterised by a diastolic flow—that is, the flow persisting during the diastole. The mean (SD) PI was 1.92 (1.18) and RI 0.70 (0.13). The estimated vascular fraction correlated with the erythrocyte sedimentation rate (ESR) (r s=0.53, p=0.03). The relative Pi (rPi), an estimate of an abnormally low resistance to vascularisation, correlated with both ESR (r s=−0.557, p<0.05) and Health Assessment Questionnaire score (r s=−0.584, p<0.05). After an injection of contrast Levovist the vascular fraction increased, while no difference in PI and RI was observed.
CONCLUSION Ultrasonography is a reliable tool for estimating the size of the joint space and the synovial activity measured by the degree of vascularisation and pattern of flow. Ultrasonography may be useful in monitoring the synovial inflammation in rheumatoid arthritis.
- Doppler ultrasonography
- rheumatoid arthritis
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Longitudinal and transversal scan of the left second metacarpophalangeal (MCP) joint of a patient with R.A..
The circumference of the synovial membrane is marked on a 2D mode picture, and the area is instantly calculated by the computer
Longitudinal scan of 2 MCP before injection of contrast. Within the Doppler frame box, blood flow is visualised as colored areas by Color-Doppler technique.
Vascular activity in the synovial membrane is clearly shown here.
Correlation between vascular fraction in the synovial membrane and ESR a/ investigator 1 , b/ investigator 2
Injection of U.S. contrast increases the ratio of colored pixels in a significant way.
P = 0.004 using Wilcoxon signed rank test
Graphical visualization of intraclass variation. Results from examination 1 are arranged in increasing numbers. Results from examination 2 are matched for each picture of the patient.
ICC investigator1 = 0.97 (p< 0.0001). ICC investigator 2 = 0.82 (p< 0.0001)
Graphical visualization of interclass variation. Results from investigator 1 are arranged in increasing numbers. Results from investigator2 are matched for each picture of the patient.
ICC = 0.81 (p< 0.0001)
Bilateral longitudinal scan of caput ulnae on patient with R.A (top).
X-ray of left wrist (bottom).
Erosion on the left caput ulnae is seen by ultrasonography. Note the smooth unbroken surface on the contralateral caput ulnae. No erosion was described by the radiologist.
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