Intraluminal vascular ultrasound: Preliminary report of dimensional and morphologic accuracy

The role of intraluminal ultrasound for diagnosis and monitoring treatment of vascular disease has yet to be defined. This study evaluated the dimensional precision and morphologic accuracy of an intraluminal ultrasound system which consists of a 5.5 French external diameter ultrasonic catheter with a central lumen for passage of a guidewire. Ultrasound images from five in-vitro human and three porcine arterial segments and two in-vivo arteriosclerotic canine arteries were compared to dimensions obtained from arteriograms and from sections of the specimens. Each gross and histological specimen and ultrasound image was scaled, photographed and enlarged up to 20 times and measured for vessel intraluminal and adventitial or outer diameter and wall thickness. Intraluminal and outer diameters and wall thickness from normal in-vitro specimens correlated significantly with dimensions obtained from histologic specimens (r=0.99, p<0.005 for internal and outer diameters and r=0.73, p<0.005 for wall thickness). The mean differences of luminal diameters measured from the vessels supported within a silicone rubber mold was 0.05±0.09 mm (n=20). Diameters of outer diameter and wall thickness were less reliably defined, the average margin of error being 0.49±0.39 mm and 0.29±0.26 mm, respectively. The mean difference between in-vivo ultrasound and arteriographic diameters was 0.61±0.38 mm (n=12). Correlation of luminal diameters between ultrasound and arteriogram was significant (r=0.76, p<0.02). The ultrasound images also differentiated a laminated appearance of normal vessel anatomy from non-uniform or dense signals seen in atherosclerotic lesions. We conclude that the definition of arterial wall morphology and accuracy of dimensions obtained using intraluminal ultrasound compared favorably to those obtained by histology and arteriography. This technology may be valuable for precise intraluminal guidance of angioplasty devices by identifying the location and consistency of atherosclerotic lesions.