Comparison of ultrasound modalities for measurement of minimum lumen diameter in autologous haemodialysis arteriovenous fistulae

This project is to investigate the variability in the measurement of minimum lumen diameter (MLD) in arteriovenous fistulae (AVF) by duplex ultrasound (DU). The specific aims of this study are to define the agreement in measured MLD of haemodialysis AVF using 2-dimensional B-mode ultrasound, 3-dimensional B-mode ultrasound, 2-dimensional power Doppler, and 3-dimensional power Doppler. Secondary aims include comparing MLD measured by ultrasound with digital subtraction angiography and spectral Doppler velocity data. Subjects that are already attending a DU for their AVF surveillance will be invited to participate. The standard protocol for AVF imaging will be carried out followed by an additional assessment of the MLD using multiple ultrasound modalities. This process will take no longer than five minutes to complete and will usually take less than two minutes. The selection of the location for minimum lumen diameter assessment will be at the discretion of the examining sonographer and in most cases will be at a stenotic site within the AVF circuit. If there is no significant stenotic site, the swing vein immediately superior to the anastomosis will be used. To reduce bias, the sonographer will record the study images without placing measurement callipers, and an independent offline process will be used involving two qualified sonographers blinded to the recorded diameter. If a study participant progresses to digital subtraction angiography (DSA) for treatment, the minimum lumen diameter from this technique will be recorded for a secondary comparison against the DU measurement techniques. The study is in exploratory/pilot staging and therefore 100 subjects will be recruited for initial data analysis.