Improved analysis of brachial artery ultrasound using a novel edge-detection software system.
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 microm (P < 0.001 at each level) between known and measured values; the mean resolving power of the software was estimated as 8.3 microm. 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 alpha 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.
Woodman
R J
RJ
Department of Medicine, The University of Western Australia, Perth 6001, Australia.
Playford
D A
DA
Watts
G F
GF
Cheetham
C
C
Reed
C
C
Taylor
R R
RR
Puddey
I B
IB
Beilin
L J
LJ
Burke
V
V
Mori
T A
TA
Green
D
D
D000704:Analysis of Variance; D001794:Blood Pressure; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D002138:Calibration; D003196:Computer Graphics; D004562:Electrocardiography; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D005996:Nitroglycerin / Q000494:pharmacology; D015588:Observer Variation; D019047:Phantoms, Imaging; D012016:Reference Values; D015203:Reproducibility of Results; D012984:Software; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014743:Videotape Recording
D008055:Lipids; D005996:Nitroglycerin