title: Golay pulse encoding for microbubble contrast imaging in ultrasound.
abstract: We present a technique that uses Golay phase encoding, pulse inversion, and amplitude modulation (GPIAM) for microbubble contrast agent imaging with ultrasound. This technique improves the contrast-to-tissue ratio (CTR) by increasing the time-bandwidth product of the insonating waveforms. A nonlinear pulse compression algorithm is used to compress the signal energy upon receive. A 6.5-dB improvement in CTR was observed using an 8-chip GPIAM sequence compared to a conventional pulse-inversion amplitude-modulation sequence. The CTR improvement comes at the cost of a reduction in frame rate: GPIAM coding uses four input pulses whereas most contrast imaging sequences require two or three pulses. Our results showed that the microbubble response can be phase encoded and subsequently compressed using a nonlinear matched-filtering algorithm, in order to enhance the signal from the contrast agent, while maintaining resolution and suppressing the tissue signal.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada. cleavens@uhnres.utoronto.ca
authors.forename: Claudia
authors.initials: C
authors.lastname: Leavens
authors.forename: Ross
authors.initials: R
authors.lastname: Williams
authors.forename: F Stuart
authors.initials: FS
authors.lastname: Foster
authors.forename: Peter N
authors.initials: PN
authors.lastname: Burns
authors.forename: Michael D
authors.initials: MD
authors.lastname: Sherar
mesh_terms: D000465:Algorithms; D003287:Contrast Media; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D045423:Microbubbles; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media