Nonlinear coded excitation method for ultrasound contrast imaging

Borsboom, J.; Chin, Chien Ting; Jong, Nico de

doi:10.1016/s0301-5629(02)00712-3

Cited by 71 publications

(46 citation statements)

References 8 publications

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“…US-CAs not only increase US reflexion, but also emit additional US signals by their harmonic response [32][33][34][35][36][37]. These can be visualised by a variety of US techniques, both with basic grey scale imaging or using more novel techniques such as harmonic imaging and pulse inversion, Doppler techniques and other dedicated contrast visualisation tools are presently incorporated in practically all high-end US systems, based partially on nonfundamental response [32,[38][39][40]. More recently, low mechanical index ("low-MI") contrast imaging techniques have enabled an even longer duration of adequate signal response with very little US-CA destruction, thus improving real-time assessment of enhancement dynamics.…”

Section: Discussionmentioning

confidence: 99%

Application of a second-generation US contrast agent in infants and children—a European questionnaire-based survey

Riccabona

2012

Pediatr Radiol

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Background No US contrast agent (US-CA) is currently licensed for use in children.Objective To survey the off-label use in children of a second-generation US-CA. Materials and methods Questionnaires were e-mailed to European paediatric radiologists, who were asked about their experience with the second-generation US-CA Sonovue® (Bracco, Milan, Italy). Number of examinations per indication and adverse effects were recorded. Examinations were categorised by intravenous or intracavitary use of US-CA. Results Out of 146 respondents, 88 stated that they did not perform contrast-enhanced US in children, but 36 of these (44%) would appreciate paediatric approval. Fortyfive centres reported 5,079 examinations in children (age mean: 2.9 years; range: birth-18 years, M/F: 1/ 2.8). The majority (4,131 [81%] in 29 centres) were intravesical applications. The minority (948 [19%] in 30 centres) were intravenous applications. No adverse effects had been recorded from intravesical use. Six minor adverse effects (skin reaction, unusual taste, hyperventilation) had been recorded after five intravenous studies (0.52%). Conclusion Responses suggest a favourable safety profile of this second-generation US-CA in children. It also demonstrates a demand for such US-CA from paediatric radiologists.

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Section: Discussionmentioning

confidence: 99%

Application of a second-generation US contrast agent in infants and children—a European questionnaire-based survey

Riccabona

2012

Pediatr Radiol

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“…[13][14][15][16] Using wideband chirps such as those employed in B-Mode imaging for subharmonic imaging can cause the overlay of the fundamental and subharmonic spectrum; the energy in the fundamental frequency band may leak into the energy in the subharmonic frequency band. 15 In such cases, it may not be possible to completely eliminate the fundamental energy associated with tissue backscatter, resulting in loss of imaging specificity.…”

Section: Vc Excitation Pulse Parametersmentioning

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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“…They have also been implemented to improve the contrast to tissue ratio when imaging with microbubbles [41], [42]. It has been proposed that due to the polydisperse nature of microbubble populations, if the frequency range of the chirp were to match those of the resonant frequency of the population, a greater acoustic response could be achieved [43].…”

Section: Introductionmentioning

confidence: 99%

Increasing the sonoporation efficiency of targeted polydisperse microbubble populations using chirp excitation

McLaughlan

Ingram

Smith

et al. 2013

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-The therapeutic use of microbubbles for targeted drug or gene delivery is a highly active area of research. Phospholipid-encapsulated microbubbles typically have a polydisperse size distribution over the 1-10 µm range and can be functionalised for molecular targeting as well as loaded with drug-carrying liposomes. Sonoporation through the generation of shear stress on the cell membrane by microbubble oscillations is one mechanism that results in pore formation in the cell membrane and can improve drug delivery. A microbubble oscillating at its resonant frequency would generate maximum shear stress on a membrane. However, due to the polydisperse nature of phospholipid microbubbles, a range of resonant frequencies would exist in a single population. In this study, the use of linear chirp excitations was compared with equivalent duration and acoustic pressure tone excitations when measuring the sonoporation efficiency of targeted-microbubbles on human colorectal cancer cells. A 3-7 MHz chirp had the greatest sonoporation efficiency of 26.9 ±5.6 %, compared with 16.4 ±1.1 % for the 1.32-3.08 MHz chirp. The equivalent 2.2 and 5 MHz tone excitations have efficiencies of 12.8 ±2.1 % and 15.6 ±1.1 %, respectively, which were all above the efficiency of 4.1 ±3.1 % from the control exposure.

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Nonlinear coded excitation method for ultrasound contrast imaging

Cited by 71 publications

References 8 publications

Application of a second-generation US contrast agent in infants and children—a European questionnaire-based survey

Application of a second-generation US contrast agent in infants and children—a European questionnaire-based survey

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

Increasing the sonoporation efficiency of targeted polydisperse microbubble populations using chirp excitation

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