SMALL ARTERIES CAN BE ACCURATELY STUDIED IN-VIVO, USING HIGH-FREQUENCY ULTRASOUND

We have validated measurements of diameters of the superficial tempora l artery and other small arteries in man with a newly developed 20 MHz ultrasound scanner with A, B and M-mode imaging. The diameter of a re ference object was 1.202 mm vs. 1.205 mm as measured by stereomicrosco py (nonsignificant). In vitro measurements of porcine carotid arteries could be reproduced with a mean interobserver difference of 0.008 mm, and the repeatability coefficient was 0.04 mm (1.4%). The frontal bra nch of the human superficial temporal artery (mean 1.24 mm) was measur ed with intraobserver repeatability coefficients of 0.18 mm (13.8%) to 0.31 mm (23.4%). The interobserver mean difference was 0.01 mm (0.69% ) and the interobserver repeatability coefficient was 0.16 mm (I 1.1%) . Pulsatile changes of the cross sectional area of the radial plus the ulnar artery averaged 0.93 mm2 compared to 0.63 MM2 by strain-gauge p lethysmography (nonsignificant). Pulsations were 4.6% in the radial ar tery. We conclude that high frequency ultrasound provides an accurate and reproducible measure of the diameter of small and medium sized hum an arteries in vivo.