Settings and artefacts relevant for Doppler ultrasound in large vessel vasculitis

Abstract Ultrasound is used increasingly for diagnosing large vessel vasculitis (LVV). The application of Doppler in LVV is very different from in arthritic conditions. This paper aims to explain the most important Doppler parameters, including spectral Doppler, and how the settings differ from those used in arthritic conditions and provide recommendations for optimal adjustments. This is addressed through relevant Doppler physics, focusing, for example, on the Doppler shift equation and how angle correction ensures correctly displayed blood velocity. Recommendations for optimal settings are given, focusing especially on pulse repetition frequency (PRF), gain and Doppler frequency and how they impact on detection of flow. Doppler artefacts are inherent and may be affected by the adjustment of settings. The most important artefacts to be aware of, and to be able to eliminate or minimize, are random noise and blooming, aliasing and motion artefacts. Random noise and blooming artefacts can be eliminated by lowering the Doppler gain. Aliasing and motion artefacts occur when the PRF is set too low, and correct adjustment of the PRF is crucial. Some artefacts, like mirror and reverberation artefacts, cannot be eliminated and should therefore be recognised when they occur. The commonly encountered artefacts, their importance for image interpretation and how to adjust Doppler setting in order to eliminate or minimize them are explained thoroughly with imaging examples in this review

Focal bone involvement in inflammatory arthritis: the role of IL17

Conditions such as rheumatoid arthritis (RA) and spondyloarthritis (SpA, such as psoriatic arthritis, PsA, and ankylosing spondylitis, AS) are characterized by an imbalance between osteoclast (OC) bone resorption and osteoblast (OB) bone formation. The two conditions present substantial differences in bone involvement, which is probably related to the different expression of IL17 and TNF\u3b1, two cytokines that strongly promote osteoclastogenesis and focal bone erosions. TNF\u3b1 is the major inflammatory cytokine in RA. It acts by both triggering OC bone erosion via the RANK-RANKL system, and suppressing OB bone formation through the overexpression of DKK1, a powerful inhibitor of the WNT bone anabolic signaling pathway. Differing from TNF\u3b1, IL17 promotes also osteogenesis, particularly at inflamed sites undergoing mechanical stress, such as entheses. Therefore, in RA, where overexpression of TNF\u3b1 is higher than IL17, OC bone resorption largely prevails upon bone formation. In PsA and AS, the prevailing inflammatory cytokine is IL17, which promotes also osteogenesis. Given the prevalent involvement of entheses poor of OC, excess bone formation may even prevail over excess bone resorption. The results of clinical trials support the different pathophysiology of bone involvement in chronic arthritis. Inflammation control through anti-TNF\u3b1 agents has not resulted in incomparable effects on radiographic progression and excess bone formation in both AS and PsA. Clinical trials investigating IL17 inhibitors, such as secukinumab, in patients with psoriatic disease are underway. The preliminary results on inflammation and symptoms appear positive, while long-term studies are required to demonstrate an effect on excess bone formation