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Ann Rheum Dis. 2007 May; 66(5): 707–708.
PMCID: PMC1954626

Doppler ultrasonographic characteristics of superficial and deep‐flow signals in the knee joint pannus of patients with rheumatoid arthritis

Increased blood flow signals on power Doppler ultrasonography in the proliferated synovium (pannus) of patients with rheumatoid arthritis (RA) have been used to evaluate articular inflammation.1,2,3,4,5,6,7 Fiocco et al5 reported that, in patients with RA after 3 months of etanercept treatment, superficial layer vascularity of the knee joint pannus8 was significantly reduced, and this occurred before deep‐layer vascularity was affected. In all, 97 knee joints of 52 patients with RA were scanned longitudinally and transversely at suprapatellar recess; we measured the vascular resistance, resistance index (RI) and pulsatility index (PI) on spectral Doppler (with the lowest filter setting at 125 Hz) and 167 colour flow signals in the pannus on power Doppler (using a pulse repetition frequency of 1170–1220 Hz with maximum gain eliminating background noise). The flow signals were categorised into superficial flow signals (located in the superficial half of the pannus and fluid space) and deep flow signals (located in the deep half of the pannus) of either capsular or supracortical pannus. The mean (SD) RI value (0.724 (0.125)) of the 102 superficial flow signals (87 capsular, 15 supracortical) was significantly lower (p<0.001) than the mean (SD) RI value (0.872 (0.172)) of the 65 deep flow signals (43 capsular, 22 supracortical). The difference in mean PI values between superficial and deep signals was less significant (p = 0.002) than for mean RI values.

Subsequently, the flow signals in the joints were divided into a superficial pattern and a deep pattern on the basis of their dominant location in the pannus on both longitudinal and transverse scans. Following this, we compared 61 joints with superficial pattern signals and 36 joints with deep pattern signals with respect to the intensities of the colour flow signals (graded 0–3 by the modified Klauser's method),9 synovial effusion (graded 0–3 by the previous method)9 and synovial proliferation of thickness [gt-or-equal, slanted]2 mm (graded 0–3 by Rubaltelli's method)10 on power Doppler, as well as RI and PI values. As shown in table 11,, compared with joints with deep pattern signals, joints with superficial pattern signals had significantly higher flow signal (p<0.001) and synovial effusion (p<0.001) grades, and significantly lower RI values (p<0.001). On the other hand, joints with deep pattern signals had a significantly higher grade of synovial proliferation (p = 0.010).

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Table 1 Comparison of power Doppler and spectral Doppler characteristics between 61 knee joints with superficial pattern signals and 36 knee joints with deep pattern signals of 52 patients with rheumatoid arthritis


RA - rheumatoid arthritis


Competing interests: None declared.


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