Enhancing effect of phase coherence factor for improvement of spatial resolution in ultrasonic imaging
- 13k Downloads
Spatial resolution is one of the important factors that determines ultrasound image quality. In the present study, methods using the phase variance of ultrasonic echoes received by individual transducer elements have been examined for improvement of spatial resolution.
An imaging method, i.e., phase coherence imaging, which uses the phase coherence factor (PCF) obtained from the phase variance of received ultrasonic echoes, was recently proposed. Spatial resolution is improved by weighting ultrasonic RF signals obtained by delay-and-sum (DAS) beam forming using PCF. In the present study, alternative PCFs, i.e., exponential PCF, harmonic PCF, and Gaussian PCF, have been proposed and examined for further improvement of spatial resolution.
Spatial resolutions realized by the proposed PCFs were evaluated by an experiment using a phantom. The full widths at half maxima of the lateral profiles of an echo from a string phantom were 2.61 mm (DAS only), 1.46 mm (conventional PCF), and 0.48–0.62 mm (proposed PCFs).
The PCFs newly proposed in the present study showed better spatial resolutions than the conventional PCF. The proposed PCFs also realized better visualization of echoes from a diffuse scattering medium than the conventional PCF.
KeywordsPhase variance Coherence factor Spatial resolution Ultrasonic image
This study was supported by JSPS KAKENHI Grant Number 26289123.
Compliance with ethical standards
Animal and human subjects were not used in this study.
Conflict of interest
- 10.Blomberg AEA, Holfort IK, Austeng A, et al. APES beam forming applied to medical ultrasound imaging. IEEE Int Ultrason Symp Proc. 2009;2009:2347–50.Google Scholar