Ultrasound Imaging in Psoriatic Arthritis: What Have We Learnt in the Last Five Years?

Abstract

Psoriatic arthritis (PsA) is a complex heterogeneous disease with multiple inter-related pathologies such as synovitis, enthesitis, tendinopathy, and dactylitis. Clinical assessment is limited in its detail to assess pathology, thus in recent years, ultrasound (US) has become more popular, given its high sensitivity to detect inflammatory arthritis and ability to inform clinical decisions. Although a qualitative technique, US findings can be graded semi-quantitatively for grayscale (GS) and power Doppler (PD). Synovitis is frequently present in inflammatory arthritis pathologies, and in PsA, recent evidence shows a propensity for tendon and entheseal lesions. The presence of flexor tenosynovitis and flexor tendon insertional enthesopathy at accessory pulleys is supportive of the “Deep Koebner” concept. Peri-tendinous inflammation—mutual to PsA or rheumatoid arthritis (RA), is associated with soft tissue oedema with PD signal frequently at the flexor tendon compartments in PsA. Research on enthesitis in PsA/PsO has improved understanding in subclinical and clinical PsA, explored associations with progression to PsA, and investigated links to prognosis assessment. Dactylitis is a pathognomonic PsA lesion where US has enhanced knowledge of the disease course and pathology of lesions such as: flexor tenosynovitis; synovitis; and soft tissue oedema. Increased US sensitivity has also brought innovation including promising automated ultrasound scanning techniques. So, what have we learnt in recent years and what are the unmet needs to focus future research initiatives in this disabling disease? This narrative review article assesses the neoteric evidence, bringing into context the knowledge gained and highlighting potential areas of research.

Ultrasound-Verified Peripheral Arthritis in Patients with HLA-B*35 Positive Spondyloarthritis

“…This fact gives rise to the possibility that some subclinical synovitis were not detected. We consider this as a possible limitation of this study since some studies showed that SpA patients can have subclinical synovitis [47]. On the other hand, we had patients with PD signal grade 2 and 3, which is uncommon or absent in healthy subjects or in patients with osteoarthritis.…”

Imaging update in inflammatory arthritis

“…Although less common and less intense, and seen in fewer joints, even power Doppler (PD) signal suggestive of subclinical synovitis is present in up to 55% of healthy subjects. 7 In the study by Ji et al, 8 there was no difference between RA and non-RA groups in terms of BME, either. The location and extent of BME may help in the differential diagnosis.…”

“…Despite some research indicating PsA-specific lesions, further studies are needed to identify more specific features providing differentiation between inflammation-related enthesitis from metabolic, age-and overload-driven enthesopathy. 7,22 A further preliminary enthesitis score developed in a recent GRAPPA study has reported the ability to differentiate between PsA and healthy controls. 23 Among rheumatic diseases, RA and PsA may be especially difficult to differentiate.…”

Hand Erosive Osteoarthritis and Distal Interphalangeal Involvement in Psoriatic Arthritis: The Place of Conservative Therapy

“…Accumulating evidence is enhancing the role of ultrasonography as a useful, low-cost non-invasive technique to identify diagnostic features of EHOA and PsA [20,[30][31][32][33]. US, in fact, is able to visualize discontinuity of bone surface, joint space narrowing and osteoproliferation.…”

“…The high sensitivity of ultrasound technique to detect inflammatory signals [32,34] made this methodology able to provide detailed information also regarding PsA activity and features, as with US it has been possible to identify synovitis since subclinical stage [33]. Doppler may finally be used to identify specific features of PsA such as enthesitis and dactylitis [33] (Figure 3). Further imaging modalities provide reliable results in detection of typical lesions of both HEOA and PsA and help to make accurate diagnosis, as proved in clinical trials [35].…”