Vascular visualization is generally made by injection of contrast medium in the vascular system and performing an angiography. This technique is very useful in clinical practice, bus has drawbacks, and is even dangerous, for some applications (carotid angiography, coronary arteriography …). The goal of many researchers is to detect cardiovascular disease very early and to evaluate the clinical or surgical treatment, without any risk for the patient. It is therefore necessary to develop accurate, non-invasive methods for examination of the cardiovascular system, especially those areas accessible for surgery. Developments of such techniques may reduce the number of useless arteriographies and permit better definition of the indications for arteriography in patients whose clinical signs are not sufficient to directly justify this type of investigation.

Real-Time Blood Flow Imaging

The increasing interest shown in rapid imaging by electronic commutation of multitransducers is linked to the inherent qualities of such equipment: immediate visualization of cross-sections, can be applied to most organs, straightforward use with instruments that are easily movable, no image distortion, etc... However with the early models developed, the quality of the image was poor compared to those obtained by manual scanning. This is due to the fact that in the multitransducer arrays, mechanical focusing cannot be made in the direction of the scanning.

Ultrasonic Multitransducer Input Signal Analysis

Doppler ultrasonic vascular visualization suffers presently from two main drawbacks, namely accuracy and time needed for acquisition of the images. Solutions to these problems are studied: a new Doppler detection process is described, which allows a better sensitivity; a mathematical approach and experimental observations were made. (2) a simultaneous treatment of a whole line of observation is developed, based on the Moving Target Indicator process used in radar techniques. A prototype has been designed and the first experimental results are reported.

A. Herment

Papers

Yes-No ultrasonic Doppler method of detection for vascular imaging