Effects of swept scanning on velocity estimation

The swept-scan technique adopted in high-frequency ultrasound involves mechanically scanning a single-element transducer to acquire image data. Unlike conventional step scanning, where the image data are acquired at discrete positions, the swept-scan technique acquires the image data while the transducer is continuously moving. Such a scanning method is particularly advantageous for Doppler flow estimation because its frame rate is higher than that for the step-scan technique. However, the effects of the transducer motion on the accuracy of velocity estimation have not been studied comprehensively. This study employed a k-space approach to experimentally investigate the effects of swept scanning on both conventional Doppler axial velocity estimation and spectral-broadening-based lateral velocity estimation using a 45-MHz transducer. The results indicate that such effects must be corrected in order to obtain an accurate estimation of flow velocities.