Power Doppler Ultrasound Assessment of A1 Pulley. A New Target of Inflammation in Psoriatic Arthritis?

Objective: To determine the prevalence of grey scale and power Doppler (PD) ultrasound (US) features of A1 pulley inflammation in a cohort of psoriatic arthritis (PsA) patients compared with rheumatoid arthritis (RA) patients. Methods: Sixty patients (30 with PsA and 30 with RA) were consecutively enrolled. The main clinimetric indexes were recorded, and US assessment of A1 pulleys from second to fifth fingers bilaterally was carried out. The presence of A1 pulley inflammation, defined as PD signal within a thickened pulley, was registered. Results: A1 pulley inflammation was found in 15 of 240 fingers (6.3%) of eight PsA patients (26.7%) and in one of 240 fingers (0.4%) of one RA patient (3.3%) (p < 0.01 and p = 0.03, respectively). Seven of eight PsA patients (88%) with at least one inflamed A1 pulley had a moderate/high disease activity score. The regression linear analysis (R(2) = 0.36, adjusted R(2) = 0.31) showed that A1 pulley inflammation was correlated with Disease Activity Index for Psoriatic Arthritis (DAPSA) (β = 0.43, p = 0.03). Conclusion: US A1 pulley inflammation appears to be relatively common at patient level in PsA, seems to be a characteristic feature of PsA compared to RA, and correlates with DAPSA.