2-D and 3-D endoluminal ultrasound: vascular and nonvascular applications

Endoluminal ultrasound using catheter-based transducers has been used for the evaluation of a wide range of abnormalities. To date, one of the most promising areas of clinical application is its use intravascularly for quantitating the degree of arterial stenosis and for monitoring the therapeutic effects of angioplasty in peripheral and coronary arteries. Uses in the gastrointestinal tract include quantification of the size and wall thickness of esophageal varices, distinguishing between various submucosal lesions and measuring the degree of fibrosis in scleroderma. In the genitourinary system, endoluminal ultrasound provides a unique intraoperative tool allowing the addition of a third dimension (depth) to endourological procedures. The indications for, and the use of, endoluminal ultrasound within the upper urinary tract can be expected to increase with more experience, and the procedure has become an important technique that yields information not available through other modalities. In the bronchotracheal tree, endoluminal ultrasound allows imaging and subsequent biopsy of lymph nodes and tumors that cannot be visualized at routine bronchoscopy. Three-dimensional (3-D) reconstruction of two-dimensional (2-D) ultrasound imaging is a new method in the evolution of intraluminal imaging. It provides information about spatial relationships of anatomic structures that cannot be evaluated using conventional 2-D imaging. Although still in its infancy, 3-D endoluminal ultrasound has the potential to become a dynamic tool in both the research and clinical areas.