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.

Vascular ultrasound for the diagnosis of giant cell arteritis: a reliability and agreement study based on a standardised training programme

“…All US examinations in each centre were conducted with the same equipment (Hitachi Preirus/Ascendus in Esbjerg/Silkeborg, GE Logic E9 in Glostrup) and settings were kept unchanged throughout the study (online supplemental file I). Equipment settings, scanning techniques and image analysis were performed according to the International Workshop on Ultrasound in Large Vessel Vasculitis & Polymyalgia Rheumatica standards 14 and were in line with the proposal by Terslev et al 4 All arteries were examined in longitudinal and transversal views. In both projections, B-mode and colour Doppler examination was performed.…”

“…been developed 4 ; nevertheless, no specific training programmes exist, all the studies in a systematic literature review being conducted by expert groups. 5 Vascular US examinations are regarded as strongly operator-dependent, and to date, very few studies have investigated US reliability.…”

Clinical Applicability of Ultrasound in Systemic Large Vessel Vasculitides

“…Misinterpretation of findings can occur due to lack of expertise, improper settings, or low quality of equipment (9,61). The halo sign may not be detectable 2-4 weeks after the introduction of glucocorticoid treatment (4,16,17,24,26,38,46,47).…”

The Renal Resistive Index in Allografts: Is Sonographic Assessment Sufficiently Reproducible in a Routine Clinical Setting? – Reproducibility of the Renal Resistive Index

“…While some patient-or setting-related factors cannot be altered, there are some wellknown errors the examiner can avoid to improve the quality of the signal waveform. These errors comprise mistaking back-ground noise for real flow when gain is set too high, removing actually present low-frequency Doppler signals with an incorrect wall filter setting, creating aliasing artifacts or a small waveform when an inadequate pulse repetition frequency is used, and obtaining a mixture of signals from different vessels in close proximity to each other if the sampling volume is too large [18][19][20].…”