Chinda Samakee and Pornchai Phukpattaranont

pp. 629 - 636

Abstract

Recently, many publications reported the generation of subharmonic frequency (f₀/2) and its potential use in imaging
from ultrasound contrast agent (UCA). Subharmonic imaging (SHI) has provided better contrast resolution over the second
harmonic signals due to the lack of subharmonic generation in the tissue region. However, subharmonic separation in SHI
utilizes linear bandpass filtering only. In this paper, we compare the subharmonic separation capability of linear band filter
(LBF), pulse inversion (PI), and their combination (PILBF) based on contrast-to-tissue ratio (CTR). Results show that the
CTR values from the LBF, the PI, and the PILBF are 20.30, 40.30, and 52.74 dB, respectively. The optimal stopband attenuation and fractional bandwidth for the PILBF method are 50 dB and 10%, respectively. This high CTR value indicates the
feasibility of the PILBF method in creating high quality ultrasound image from subharmonic frequency