M J Eberle | PubMed Health

PubMed1995

Experimental studies on an efficient catheter array imaging system.

A new synthetic aperture system for intraluminal imaging has been tested using a 32 element, 20 MHz circular array wrapped around the surface of a catheter appropriate for coronary artery applications. This system is based on an optimal reconstruction method that has been extended to reduce grating lobes using a slight modification to classic synthetic aperture data acquisition. Optimal reconstruction filters have been derived for two different operating modes based on this new data acquisition strategy. Imaging results on a wire target phantom show that spatial resolution is a simple linear function of depth, reaching a minimum 6 dB beam width of approximately 2.2 wavelengths. Sidelobe levels are inherently high for this system because of the small number of firings used to synthesize an aperture. Optimal reconstruction filters, however, can reduce these sidelobes to at least -20 dB in all cases. Finally, images of an excised segment of porcine femoral artery demonstrate the overall performance of the system as an intraluminal imager.

Animals↗

PubMed1989

Clinical percutaneous imaging of coronary anatomy using an over-the-wire ultrasound catheter system.

This manuscript describes initial applications of a unique new intravascular ultrasound imaging catheter. This 5.5F catheter uses an over-the-wire design and incorporates a phased array transducer at its tip. There are no moving parts. A 360 degree image is produced perpendicular to the catheter axis using a 20 MHz center frequency. A dedicated minicomputer is used for initial image processing, as well as enhancement and analysis. Initial studies using phantoms demonstrated excellent accuracy for linear dimensions (r = 0.99, range 3.0 to 7.6 mm, image = 1.0 phantom + 0.1). Serial imaging of the same arterial segment in vitro showed good reproducibility (coefficients of variance 2.5-5.2%). Likewise, intra- and inter-observer variability in image analysis was minimal (r = 0.92-0.99). Initial in vivo studies were performed in dogs. The catheter was easily passed over a wire into mesenteric, cerebral and coronary vessels without evidence of significant vessel trauma. Subsequently, 20 patients had percutaneous coronary imaging performed during cardiac catheterization. Cardiac motion was rarely a problem and acceptable images were obtained in all but two patients. Areas of calcification, mild stenoses, branching vessels and graft atherosclerosis could be identified. We conclude that intracoronary ultrasound imaging will be useful for assessing vascular pathology, for studying both rapid change in vessel size as well as chronic progression or regression of atherosclerosis, and for assisting with new therapeutic interventions.

Angioplasty, Balloon↗