Effect of Pulse Shaping on Subharmonic Aided Pressure Estimation In Vitro and In Vivo

Objectives Subharmonic imaging (SHI) is a technique that uses the nonlinear oscillations of microbubbles when exposed to ultrasound at high pressures transmitting at the fundamental frequency ie, fo and receiving at half the transmit frequency (ie, fo/2). Subharmonic aided pressure estimation (SHAPE...

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Bibliographic Details
Published in:Journal of ultrasound in medicine 2017-01, Vol.36 (1), p.3-11
Main Authors: Gupta, Ipshita, Eisenbrey, John, Stanczak, Maria, Sridharan, Anush, Dave, Jaydev K., Liu, Ji‐Bin, Hazard, Christopher, Wang, Xinghua, Wang, Ping, Li, Huiwen, Wallace, Kirk, Forsberg, Flemming
Format: Article
Language:English
Subjects:
Animals
Contrast Media
Dogs
Ferric Compounds
Image Enhancement - methods
Iron
Microbubbles
noninvasive pressure estimation
Oxides
Phantoms, Imaging
portal hypertension
Portal Pressure - physiology
Portal Vein - diagnostic imaging
Portal Vein - physiology
pulse envelope
Reproducibility of Results
subharmonic imaging
Ultrasonography - methods
ultrasound
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Summary:Objectives Subharmonic imaging (SHI) is a technique that uses the nonlinear oscillations of microbubbles when exposed to ultrasound at high pressures transmitting at the fundamental frequency ie, fo and receiving at half the transmit frequency (ie, fo/2). Subharmonic aided pressure estimation (SHAPE) is based on the inverse relationship between the subharmonic amplitude of the microbubbles and the ambient pressure change. Methods Eight waveforms with different envelopes were optimized with respect to acoustic power at which the SHAPE study is most sensitive. The study was run with four input transmit cycles, first in vitro and then in vivo in three canines to select the waveform that achieved the best sensitivity for detecting changes in portal pressures using SHAPE. A Logiq 9 scanner with a 4C curvi‐linear array was used to acquire 2.5 MHz radio‐frequency data. Scanning was performed in dual imaging mode with B‐mode imaging at 4 MHz and a SHI contrast mode transmitting at 2.5 MHz and receiving at 1.25 MHz. Sonazoid, which is a lipid stabilized gas filled bubble of perfluorobutane, was used as the contrast agent in this study. Results A linear decrease in subharmonic amplitude with increased pressure was observed for all waveforms (r from −0.77 to −0.93; P 
ISSN:0278-4297
1550-9613
DOI:10.7863/ultra.15.11106