Intravascular ultrasound imaging: an essential component of angioplasty assessment and vascular stent deployment.

Potential early complications of balloon angioplasty include occlusion due to vessel wall recoil, medial dissection, creation of intimal flaps, spasm and luminal thrombosis. These features have also been implicated in the development of restenosis and late occlusion. As a possible solution to these problems, an endovascular scaffold (stent) was proposed by Dotter in the 1960s, and initial studies suggested that use of such a device in specific circumstances may reduce complications related to major dissection, vessel recoil and spams. This paper reports the utility of two- and three-dimensional intravascular ultrasound (IVUS) imaging in assessing arterial morphology following balloon angioplasty, and guiding the need for, and adequacy of deployment of intravascular stents. IVUS imaging provides a technique to accurately assess the immediate results of angioplasty and examine both the luminal size and contour following intervention. Accurate imaging such as this is essential for the successful use of balloon expandable stents, by ensuring correct initial positioning and complete deployment at the time of balloon expansion. Two cases are reported which highlight the important issues which are critical to the ongoing development of endovascular therapies: (i) accurate assessment of the angioplasty results, and (ii) selection and confirmation of stent deployment. We conclude that IVUS imaging may provide a new standard for the assessment of angioplasty procedures and will play a pivotal role in identifying failure mechanisms of endovascular interventions.

Three-dimensional transrectal ultrasound: preliminary patient evaluation.

Transrectal ultrasound is uniquely useful in diagnosing and localizing the extent of lower colon and rectal disease. This paper reports the preliminary evaluation of three-dimensional intraluminal ultrasound imaging of normal and diseased rectal segments. The three-dimensional reconstructions were produced using a computerized PC based image analysis system which aligns ultrasound images to produce the three-dimensional images. A unique perspective for displaying both normal and pathologic anatomy is achieved using this new technology and the method has promising diagnostic and therapeutic potentials.

Three dimensional vascular ultrasound imaging.

Intravascular ultrasound (IVUS) is a new catheter-based system that produces two-dimensional (2D) images of vascular structures. Existing systems produce real-time, cross-sectional "slices" of vessels using 5.0 French (Fr) (30 MHz) and 8.0 Fr (20 MHz) IVUS catheters containing ultrasound transducers at the tip. Computerized, three-dimensional (3D) reconstruction of these 2D images using a personal computer- (PC) based image analysis system is described. A set (n = 90) of longitudinally aligned, consecutive images is sampled from a 5.0 cm vessel segment, and computerized processing creates rendered 3D images. By adjusting image density threshold and viewing angle, the morphology, location, and spatial distribution of arterial pathology can be seen. Refinements in computer hardware and software have reduced processing time and improved image resolution to the point where 3D IVUS imaging is a clinically applicable tool. Possible applications include diagnosis of complex arterial pathology, guidance of intraluminal instruments, and assessment of the effects of endovascular interventions.

A new technique for intraluminal hollow organ imaging: three-dimensional ultrasound.

Intraluminal ultrasound (ILUS) is a new catheter-based system which produces two-dimensional (2D), cross-sectional images of tubular structures. The principle of image acquisition using 5.0 Fr (30 MHz) and 8.0 Fr (20 MHz) ILUS catheters containing ultrasound transducers at the tip, is equally applicable to all tubular or hollow organs. This article illustrates the feasibility of intraluminal imaging of hollow organ structures, and describes computerized three-dimensional (3D) reconstruction of the 2D images, using a PC-based image analysis system. A set (n = 90) of longitudinally aligned, consecutive 2D images was sampled from various organs (canine bladder, urethra, jejunum, esophagus, and trachea) and computer processed to produce 3D images. By adjusting image density threshold and viewing angle, the lumen and wall morphology can be examined in any projection. Possible applications include diagnosis of lumen encroaching pathology, guidance of intraluminal instruments, and assessment of the effects of endoluminal interventions.