Pinpoint doppler graphic12/21/2023 ![]() ![]() The type of flow in arteries affected by LVV is fast flow. In arthritic joints the type of vascularization is characterised by slow flow, and the vessels of interest are invisible without the Doppler mode with minimal movement of the vessel wall during the cardiac cycle. Though Doppler ultrasound is used routinely in most rheumatology departments for patients with arthritis, the Doppler settings for ultrasound in large vessels and the resulting artefacts are very different. Some of the vasculitis features, such as increased intima-media vessel wall thickness, are diagnosed with greyscale (GS) ultrasound alone but Doppler ultrasound plays a role by aiding in visualising the vessel and the wall swelling and pinpointing the areas of stenosis or occlusion and, hence, the importance of changes in flow velocity and direction. Several publications have highlighted the use of ultrasound for diagnosing LVV and monitoring disease activity and in some institutions it has even substituted for temporal artery biopsy. A distinctive part of LVV is an increase of the intima-media vessel wall thickness, which may result in stenosis or even occlusion (altering the flow profile and changing the blood velocity in the affected areas of the vessels). Takayasu arteritis appears in younger people with disease onset before the age of 40 years. Giant cell arteritis is seen in people aged >50 years, with a predilection for the temporal and other extracranial arteries such as the axillary and subclavian arteries. LVV includes giant cell arteritis with and without large vessel involvement and Takayasu arteritis. 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.ĭiagnosis and monitoring of large vessel vasculitis (LVV) are part of most rheumatology clinics. Some artefacts, like mirror and reverberation artefacts, cannot be eliminated and should therefore be recognised when they occur. Aliasing and motion artefacts occur when the PRF is set too low, and correct adjustment of the PRF is crucial. Random noise and blooming artefacts can be eliminated by lowering the Doppler gain. 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. Doppler artefacts are inherent and may be affected by the adjustment of settings. 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. This is addressed through relevant Doppler physics, focusing, for example, on the Doppler shift equation and how angle correction ensures correctly displayed blood velocity. 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. The application of Doppler in LVV is very different from in arthritic conditions. ![]() ![]() Ultrasound is used increasingly for diagnosing large vessel vasculitis (LVV). ![]()
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