Measurements obtained by ultrasound are considered more accurate than angiographic dimensions. In addition to luminal measurements, the ability of coronary ultrasound to image the soft tissues within the arterial wall enables characterization of atheroma size, plaque distribution and lesion composition during diagnostic or therapeutic catheterization. Accordingly, ultrasound can detect the presence or absence of structural abnormalities of the vessel wall after mechanical interventions, including dissections, tissue flaps, and irregular surface features. Intravascular Ultrasound Devices Intracoronary ultrasound equipment consists of two major components, a catheter incorporating a miniaturized transducer and a console containing the necessary electronics to reconstruct an ultrasound image. Modern catheters typically range in size from 2.9F to 3.5F, a corresponding diameter of 0.96 to 1.17 mm.
Most systems use a monorail design to facilitate rapid catheter exchanges.
An additional artifact, transducer ring-down, appears in virtually all medical ultrasound devices. All intravascular imaging systems are vulnerable to geometric distortion produced by oblique imaging. Thus, when the ultrasound beam interrogates a plane not orthogonal to the vessel walls, an artery with a circular lumen appears elliptical in shape. Repeat ultrasound studies can be unreliable owing to imprecision in placement of the imaging transducer in exactly the same location on reimaging. Although intravascular ultrasound requires intracoronary instrumentation, initial studies conducted during diagnostic catheterization demonstrated few serious untoward effects.