Background--Using new, very high-resolution ultrasound biomicroscopy, we examined the thickness of artificial layers of silicone and intima thickness (IT) of radial and anterior tibial arteries in healthy subjects and in patients with vascular disease.

Methods and Results--Silicone layers of varying thicknesses and mesenteric artery specimens obtained from 18 patients undergoing colectomy were measured by both ultrasound biomicroscopy (55 MHz) and morphometry. There was high correlation (r>0.9; P<0.0001) between IT and intima area versus ultrasound biomicroscopy. In 90 healthy subjects (aged between 10 and 90 years), radial and anterior tibial arterial IT and intima-media thickness were measured, as was carotid intima-media thickness in 56 of these subjects. Age was strongly related with both media thickness and IT of both peripheral arteries. Correlations were found between carotid intima-media thickness and both radial and anterior tibial IT/intima-media thickness (r=0.44 to 0.53; P<0.0001). The IT-to-lumen diameter ratio increased with age and was larger at all ages in the anterior tibial artery (0.067±0.034) versus the radial artery (0.036±0.012; P<0.0001). A thicker radial intimal layer was found in patients with peripheral artery disease.

Conclusion--This study is the first to our knowledge in humans to show the feasibility of measuring IT of the radial and anterior tibial arteries using very high-resolution ultrasound. IT progresses with age, and the IT-to-lumen diameter ratio is largest in the arteries of the foot. Assessment of IT by ultrasound biomicroscopy may aid in detecting early peripheral vascular abnormalities.