Experimental studies for noninvasive assessment of portal vein pressure based on contrast enhanced subharmonic sonographic imaging / 生物医学工程学杂志

Portal hypertension (PHT) is a common complication of liver cirrhosis, which could be measured by the means of portal vein pressure (PVP). However, there is no report about an effective and reliable way to achieve noninvasive assessment of PVP so far. In this study, firstly, we collected ultrasound images and echo signals of different ultrasound contrast agent (UCA) concentrations and different pressure ranges in a low-pressure environment based on an

Broadband subharmonic active cavitation imaging with high cavitation to tissue ratio / 生物医学工程学杂志

To improve the cavitation-to-tissue ratio (CTR) of cavitation imaging during the treatment with high-intensity focused ultrasound (HIFU), we proposed a pulse inversion based broadband subharmonic cavitation imaging method (PIBSHI). Due to the fact that the subharmonic signal is a unique nonlinear vibration characteristic of cavitation bubbles, we extracted the broadband subharmonic signal to get a high-CTR cavitation imaging. The simulation showed that the subharmonic signal produced by cavitating bubbles with different sizes varied, and the signal was stronger than other subharmonics when the bubbles' resonant frequency was close to 1/2 subharmonic frequency. Further experiment results demonstrated that compared with the conventional B-mode images, broadband subharmonic cavitation imaging (BSHI) has improved the CTR by 5.7 dB, and the CTR was further improved by 3.4 dB when combined with pulse inversion (PI) technology. Moreover, when the bandwidth was set to 100%~140% of the 1/2 subharmonic frequency in PIBSHI, the CTR was the highest and the imaging showed the optimal quality. The study may have reference value for the development of precise cavitation imaging during HIFU treatment, and contribute to improve the safety of HIFU treatment.

Nonlinear properties of ultrasound contrast microbubbles and their application in nonlinear ultrasound contrast imaging / 中国介入影像与治疗学

When insonated with fundamental frequency, the ultrasound contrast microbubbles are able to produce nonlinear scattering and generate nonlinear frequencies. The nonlinear properties of these microbubbles can be used to create nonlinear imaging modality and significantly improve the diagnostic capability of medical ultrasound. This paper was a review about the current research progress of nonlinear properties of ultrasound contrast microbubbles and nonlinear imaging, especially about the nonlinear properties under different frequency, acoustic pressure and the application of nonlinear imaging. A prospect of the future research and application was finally put forward in the paper.