A vector Doppler ultrasound instrument

The vector Doppler is a multiple transducer pulsed Doppler system designed to detect the three dimensional nature of hemodynamics using, simultaneously, one focused transmitting/receiving transducer and four unfocused receiving transducers. The system reduces the refractive errors incurred in utilizing multiple transmitting/receiving transducers and the time constraints of requiring multiple cardiac cycles. The validity of this concept was tested using a steady state stenosis model. Five different stenosis were used: 0%, 20%, 40%, 60%, and 80% based on tube diameter. The system was operated at three flow rates resulting in a total of 15 experimental cases with unstenosed tube Reynolds numbers from 300 to 1100 and stenotic Reynolds numbers to 5600. Modal velocity waveforms and velocity spectral magnitude waveforms were generated from data gathered downstream of the stenoses. The results demonstrate that the system is capable of detecting parabolic flow, the region of high speed para-axial flow corresponding to jet flow, the recirculation zone between the jet and the tube wall, and the region of jet break up. The system is also capable of measuring the increase in spectral broadening and change in velocity direction associated with regions of non-axial flow. Eddy structures may be revealed upon removal of the dominating jet wobble