| 主权项 |
1. A method of producing blood flow velocity vector imagery, comprising:
emitting at least two unfocused plane wave acoustic signals at at least two specific angles to a transducer array into a medium over substantially an entire field of measurement; receiving scattered and reflected ultrasonic signals on the transducer array in response to the emission; processing the received ultrasonic signals to extract information to construct a blood flow vector velocity signal by:
wall filtering the extracted information;using the wall-filtered information to form autocorrelation values and Doppler frequency estimates;partitioning of a bistatic range-rate model, f=Av+b+e, where the flow velocity vector at the image point is v=[νx,νz]T, b represents bias due to aliasing, e is stochastic error, and the model matrix A is dimensioned [M×2] and has rows am(θm), where:am=1λ[sin(θm),1+cos(θm)] with explicit terms for bias due to aliasing of Doppler frequencies, into linear and nonlinear parts; andsolving the partitioned model by the weighted least squares scheme for the blood flow vector velocity signal v corresponding to at least one point in the medium;generating blood flow vector velocity signals;detecting the presence of blood flow corresponding to a display device pixel by qualifying blood flow vector velocity signals through a series of tests on values of quality metrics produced as byproducts of the blood flow vector velocity estimation procedure; andgenerating on a display device blood flow vector velocity imagery from the blood flow vector velocity signals. |
