Evaluation of error factors depending on ultrasonic transmitted beamwidth in measurement of myocardial minute velocity

A measurement by transmitting ultrasonic non-focusing beams increases the temporal resolution but causes an error in the velocity measurements because of the lower signal-to-noise ratio (SNR) caused by the lower transmitted power and the lower spatial resolution. In the present study, we evaluated the relationship between the SNR and the transmitted beamwidth by the phantom experiment. The SNR decreased as the beamwidth became wider, and the measurement error increased when SNR was lower than 10 dB. Furthermore, the error factor due to the low spatial resolution more affected the measurement error than that due to the low transmitted power.