Which ultrasound lesions contribute to dactylitis in psoriatic arthritis and their reliability in a clinical setting

OBJECTIVES

To explore the frequency of ultrasound elementary lesions in dactylitis in psoriatic arthritis (PsA), and the reliability of scoring these lesions in a clinical setting.

METHODS

In 31 patients with PsA and clinical dactylitis, ultrasound assessment of the affected finger or toe was performed using greyscale and color Doppler mode. One examiner scanned all patients and a second examiner scanned 10 patients for inter-reader reliability. For each digit, the following lesions were evaluated: subcutaneous edema; soft tissue thickening; synovitis of the digital joints; tenosynovitis of the flexor tendon; enthesitis at the deep flexor tendon and the extensor tendon entheses; and paratenonitis of the extensor tendon. A dactylitis sum-score was calculated. Findings in clinically tender and non-tender digits were compared.

RESULTS

The most frequent lesions were soft tissue thickening (81%) and subcutaneous edema (74%) followed by synovitis (56-68%) and flexor tenosynovitis (52%). Color Doppler was most frequently found subcutaneously (55%) and around the flexor tendons (45%). All lesions were typically found in combinations, most commonly subcutaneous edema and synovitis (71%), subcutaneous edema and flexor tenosynovitis (52%), and all three in combination (52%). Tender digits had a higher dactylitis sum-score and numerically higher prevalence of most lesions than non-tender digits. Intra- and inter-reader agreements were moderate to excellent, though lower for few components of digital enthesitis, especially hypoechogenicity.

CONCLUSION

Dactylitis in PsA appears to encompass several lesions, most often subcutaneous changes combined with synovitis and/or flexor tenosynovitis. Reliability of scoring established ultrasound lesions of dactylitis in a clinical setting is moderate-excellent. Key Points • Dactylitis in psoriatic arthritis consists of multiple ultrasound lesions • A dactylitis ultrasound sum-score gives an impression of severity by including all lesions • Reliability of ultrasound scoring of dactylitis components is good.

Imaging in peripheral and axial psoriatic arthritis: contributions to diagnosis, follow-up, prognosis and knowledge of pathogenesis

Imaging in psoriatic arthritis (PsA) is rapidly evolving, and the use of sensitive modalities both in clinical research and routine care is increasing. This article provides an overview of current knowledge of different imaging methods in PsA, including current and possible future use in diagnosis, prognosis and clinical management, value in understanding pathogenesis, and latest activities to establish responsive imaging outcome measures. Much research remains to be performed concerning imaging in PsA, particularly on its optimal use in routine clinical care, the clinical consequences of imaging-detected subclinical disease, and specific and sensitive PsA imaging outcome measures.