title: An ultrasonic microbubble semi-intermodulated imaging technique.
abstract: The performance of contrast imaging technique is critically influenced by some factors, such as spatial resolution, agent-to-tissue ratio, lifetime of contrast agents and attenuation effect. By using a transducer with higher frequency and higher bandwidth of transmitted signals, the spatial resolution can be improved. Similarly, a better signal-to-interference ratio (SIR) can improve the agent-to-tissue ratio, a lower transmission pressure can prolong the lifetime of contrast agents and a lower center frequency can diminish the attenuation effect. We extend the two-frequency analytic solutions of to approximate the short-pulse responses of microbubbles in a low-amplitude field. Based on their results, there is an expected component near 0 Hz in the spectrum of bubble echoes excited by a short pulse of ultrasound. Here, this component is called the low-frequency response; and it is shown to have a special bandwidth-dependent property and to have potential applications in imaging. We have established the procedure of semi-intermodulated (low-frequency) imaging and the effects of the attenuation effect on imaging resolution, SIR, and signal-to-noise ratio are also analyzed. The obtained experimental images demonstrate that the SIR in semi-intermodulated imaging is better than that in fundamental imaging under various attenuation conditions.
authors.affiliation: Medical Group, Research Center, Micro-Star International Co., Ltd., Taipei City, Taiwan. chungyuowu@msi.com.tw
authors.forename: Chung-Yuo
authors.initials: CY
authors.lastname: Wu
authors.forename: Jenho
authors.initials: J
authors.lastname: Tsao
authors.forename: Yi-Hong
authors.initials: YH
authors.lastname: Chou
mesh_terms: D003287:Contrast Media; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D045423:Microbubbles; D019047:Phantoms, Imaging; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*
chemical_list: D003287:Contrast Media