The Doppler kinetics of microbubble echo contrast

Schwarz, Karl Q.; Chen, X.; Bezante, Gian Paolo; Phillips, Daniel; Schlief, Reinhard

doi:10.1016/0301-5629(96)00021-x

Cited by 39 publications

(26 citation statements)

References 16 publications

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“…[18][19][20][21][22][23] Second harmonic and subharmonic oscillations of the contrast agent have been exploited to improve imaging specificity of blood-filled structures. [24][25][26][27] In harmonic imaging (HI), ultrasound signals are transmitted at the fundamental frequency (f o ) and echo signals are received at the second harmonic (2f o ), at which the ultrasound contrast agent produces a distinct signal.…”

Section: Previous Related Workmentioning

confidence: 99%

Improving the sensitivity of high‐frequency subharmonic imaging with coded excitation: A feasibility study

Shekhar

Doyley

2012

Medical Physics

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Purpose: Subharmonic intravascular ultrasound imaging (S-IVUS) could visualize the adventitial vasa vasorum, but the high pressure threshold required to incite subharmonic behavior in an ultrasound contrast agent will compromise sensitivity-a trait that has hampered the clinical use of S-IVUS. The purpose of this study was to assess the feasibility of using coded-chirp excitations to improve the sensitivity and axial resolution of S-IVUS. Methods: The subharmonic response of Targestar-p TM , a commercial microbubble ultrasound contrast agent (UCA), to coded-chirp (5%-20% fractional bandwidth) pulses and narrowband sine-burst (4% fractional bandwidth) pulses was assessed, first using computer simulations and then experimentally. Rectangular windowed excitation pulses with pulse durations ranging from 0.25 to 3 ls were used in all studies. All experimental studies were performed with a pair of transducers (20 MHz/10 MHz), both with diameter of 6.35 mm and focal length of 50 mm. The size distribution of the UCA was measured with a Casy TM Cell counter. Results: The simulation predicted a pressure threshold that was an order of magnitude higher than that determined experimentally. However, all other predictions were consistent with the experimental observations. It was predicted that: (1) exciting the agent with chirps would produce stronger subharmonic response relative to those produced by sine-bursts; (2) increasing the fractional bandwidth of coded-chirp excitation would increase the sensitivity of subharmonic imaging; and (3) coded-chirp would increase axial resolution. The experimental results revealed that subharmonic-to-fundamental ratios obtained with chirps were 5.7 dB higher than those produced with sine-bursts of similar duration. The axial resolution achieved with 20% fractional bandwidth chirps was approximately twice that achieved with 4% fractional bandwidth sine-bursts. Conclusions: The coded-chirp method is a suitable excitation strategy for subharmonic IVUS imaging. At the 20 MHz transmission frequency and 20% fractional bandwidth, coded-chirp excitation appears to represent the ideal tradeoff between subharmonic strength and axial resolution.

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Section: Previous Related Workmentioning

confidence: 99%

Improving the sensitivity of high‐frequency subharmonic imaging with coded excitation: A feasibility study

Shekhar

Doyley

2012

Medical Physics

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“…The slope is approximately doubled when either the concentration or the flow rate is doubled. The decay rate depends on flow rate but not on the concentration, as predicted by Schwarz et al [11]. Hence, the decay rate carmot be used as a predictor of local tumor perfusion.…”

Section: Resultsmentioning

confidence: 99%

Estimation of Tumor Angiogenesis With Constrast Enhanced Subharmonic Ultrasound Imaging

Forsberg¹

2003

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“…The system transfer function for this model is given by (3) A delay time related to the travel time of the indicator from the previous mixing chamber to the current mixing chamber (or the observation site) may be incorporated into the transfer function, but it is omitted here for simplicity.…”

Section: A System Model Of a Single Mixing Chambermentioning

confidence: 99%

“…Other parameters of the concentration-time curve include the centroid defined as (4) For the simple mixing chamber model given by (3), it can be shown that (5) where is the centroid of the input function, and is the time constant of the mixing chamber. The above discussion is valid regardless of the actual shape of the input function.…”

Section: A System Model Of a Single Mixing Chambermentioning

confidence: 99%

“…When used in this way, the sonographer benefits from a prolonged, steady-state contrast effect. The duration of contrast effect (length of time in which the detected signal is above background by a threshold number, such at 3 dB) is expected to be proportional to the logarithm of the dose divided by the total blood volume [3]. When administered at the recommended (pharmacological) dose, there is an initial shadowing effect during a short time subsequent to the initial injection, commonly referred to as the first pass of the agent, followed by a long period of decreasing enhancement.…”

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confidence: 99%

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A mathematical model for the assessment of hemodynamic parameters using quantitative contrast echocardiography

Chen

Schwarz

Phillips

et al. 1998

IEEE Trans. Biomed. Eng.

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Abstract-A mathematical model for the assessment of hemodynamic parameters using quantitative echocardiography is presented. The method involves the intravenous injection of an ultrasonic echo contrast agent. The relative enhancement of the backscattered ultrasound intensity is measured as a function of time (the time-intensity curve). From this measurement, the volume flow rate (cardiac output) and the mixing volume are calculated. Relevant acoustic properties of the ultrasound contrast agent are discussed. An in vitro experiment is performed to corroborate the theory presented.

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The Doppler kinetics of microbubble echo contrast

Cited by 39 publications

References 16 publications

Improving the sensitivity of high‐frequency subharmonic imaging with coded excitation: A feasibility study

Improving the sensitivity of high‐frequency subharmonic imaging with coded excitation: A feasibility study

Estimation of Tumor Angiogenesis With Constrast Enhanced Subharmonic Ultrasound Imaging

A mathematical model for the assessment of hemodynamic parameters using quantitative contrast echocardiography

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