A method for assessing blood flow in a tissue involving directing a beam through the tissue along overlapping lines of sight and then generating the blood flow data from where the ultrasonic beams overlap to evaluate blood flow in the tissue. More specifically, spatially overlapping beams are generated at a fixed temporal intervals. Spatial overlap allows the spatial distance between overlapping lines-of-sight to be ignored, while moving reflectors within any overlapping line-of-sight will cause detectable changes in range of the moving reflector from one line-of-sight to the next. The rate of motion is determined from the measured change in range and the known time interval between vectors. Processing of data includes alignment of data between lines-of-sight to suppress artifactual motion and a wall filter for isolation of flow-data from stationary structures. An apparatus for assessing blood flow includes a transmission system and a storage system. The transmission system generates a beam which is sequentially transmitted towards the tissue along a plurality of overlapping lines of sight and receives echo data from the transmission along each of the lines of sight. The storage system stores the echo data.