Improved analysis of brachial artery ultrasound using a novel edge-detection software system.
Woodman, R. J., D. A. Playford, G. F. Watts, C. Cheetham, C. Reed, R. R. Taylor, I. B. Puddey, L. J. Beilin, V. Burke, T. A. Mori, and D. Green.
Departments of 1Medicine and 2Human Movement and Exercise Science, The University of Western Australia, Perth 6001; and Departments of 4Cardiology and 3Medical Physics, The West Australian Heart Research Institute Royal Perth Hospital, Perth 6000, Western Australia, Australia.
APStracts 8:0246A, 2001.
Brachial artery ultrasound is commonly employed for noninvasive assessment of endothelial function. However, analysis is observer dependent and susceptible to errors. We describe studies on a computerized edge-detection and wall-tracking software program to allow more accurate and reproducible measurement. In study 1, three purpose-built Perspex phantom arteries, 3.00, 4.00, and 6.00 mm in diameter, were measured with the software. There was a mean bias of 11 µm (P < 0.001 at each level) between known and measured values; the mean resolving power of the software was estimated as 8.3 µm. In study 2, the mean intraobserver coefficient of variation of repeated measures of flow-mediated dilation (FMD) using the software (6.7%) was significantly lower than that for traditional manual measurements using the intima-lumen interfaces (24.8%, P < 0.05) and intima-media interfaces (32.5%, P < 0.05). In study 3, 24 healthy volunteers underwent repeat testing twice within 1 wk; the coefficients of variation for between-visit reproducibility of FMD and response to glyceryl trinitrate using the software were 14.7 and 17.6%, respectively. Assuming 80% power and an a of 0.05, eight subjects with matched controls would be required, in a parallel designed study, to detect an absolute 2.5% change in FMD. In summary, we have developed a semiautomated computerized vascular ultrasound analysis system that will improve the power of clinical intervention studies to detect small changes in arterial diameter.
Received 29 December 2000; accepted in final form 20 March 2001
APS Manuscript Number A1203-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 18 June 2001