Resolution limitations in intravascular ultrasound imaging.

Interest in the use of ultrasound to characterize the structure and composition of blood vessel walls has risen dramatically as a result of the development of intravascular ultrasonic imaging transducers mounted on the tips of small-diameter catheters. A study of the resolution of these transducers is needed to understand the limitations in the visualization of these structures. Theoretic and experimental studies of the resolution of the two principal designs of intravascular ultrasonic transducers, the mechanically scanned single element and the multielement circular array, were carried out. Comparisons of the two designs reveal that they have similar resolutions. However, the resolutions in two of the three dimensions are shown to decrease linearly with increasing radial distance. Significant errors in image interpretation, particularly in larger diameter vessels, will result if this variation in resolution is not accounted for.