Coherence factor based on phasor dispersion for medical ultrasound imaging

To reconstruct ultrasonic B-mode image with improved quality, it is desirable to eliminate the contributions originating from the off-axis reflectors in the backscattered echoes. A new coherence factor based on phasor dispersion (PDCF) is presented for side lobe and clutter suppression. This method utilizes the coherence of complex-value aperture data to determine the interference degree to the main target (or, the amount of main lobe versus clutter) in the received signals. Based on a measurement of phasor dispersion and a theoretical maximum estimated by the statistics of echo envelope, PDCF is devised and weights the coherent beamsum. It results in images with reduced clutter and enhanced contrast. The predicted improvements on image quality were verified by simulated point and cyst phantoms using Field II.