This grant will fund the investigation of ultrasound Doppler techniques to estimate blood velocity and detect blood flow related conditions. By manipulating the aperture of an ultrasound transducer, a line type echo spectra will be produced from which the 3-D blood velocity vector, rather than merely the velocity components along and normal to the sound beam axis, will be estimated. Capillary blood flow and perfusion also will be measured through the use of ultrasound contrast materials which can be injected into the blood. These contrast agents have a much stronger echo at the second harmonic of the incident radiation than does tissue and therefore the ratio of the capillary blood echo to that of the surrounding tissue will be enhanced. This research is important since it could lead to advances in ultrasound technology, including the improvement of the performance of current transducers and the design of transducers with certain operating features. The research also could enable flow measurements to be made in some locations where conventional systems are ineffective. The contrast studies should enable more effective visualization of the degree of perfusion. These latter studies also should enable the first measurement of capillary flow to be made using ultrasound.
