Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

Surrounding Tissue ◽

High Frequencies ◽

Ultrasound Contrast ◽

Wide Range ◽

The microcirculation can be differentiated from the surrounding tissue using high frequency ultrasound subharmonic imaging. This imaging technique relies on the detection of energy scattered from ultrasound contrast agents at half the transmit frequency due to their resonant oscillations. The current contrast agents and the subharmonic imaging parameters have not been optimized for high frequencies. Moreover, the origin of subharmonic generation from submicron bubbles is not well-understood. The size distribution of Definity™ phospholipid-shelled microbubbles was altered to find the optimal bubble size to be resonant over a wide range of high frequencies. The resonant behaviour of bubbles was investigated through in vitro attenuation measurements. The transmit frequency and pressure were varied to optimize the backscattered subharmonic signal. Alteration of Definity™ population significanatly improved the scattering for subharmonic imaging at 20 MHz. A peak negative pressure between 400 to 600 kPa is suggested for this frequency range.

Modeling of high‐frequency ultrasound contrast agents.

The Journal of the Acoustical Society of America ◽

10.1121/1.3384235 ◽

2010 ◽

Vol 127 (3) ◽

pp. 1827-1827

Author(s):

John Allen ◽

Fanny Cugnet ◽

Jonathan Mamou ◽

Paul Lee ◽

Parag Chitnis ◽

...

Keyword(s):

Contrast Agents ◽

High Frequency ◽

Ultrasound Contrast ◽

Modelling high frequency ultrasound scattering from cells and ultrasound contrast agents

10.32920/ryerson.14658069.v1 ◽

2021 ◽

Author(s):

Omar Falou

Keyword(s):

Contrast Agents ◽

High Frequency ◽

Polystyrene Microspheres ◽

Surface Modes ◽

Ultrasound Contrast ◽

Resonance Frequencies ◽

Ultrasound Scattering ◽

High frequency ultrasound has been shown to detect structural and physical changes in cell ensembles during apoptosis and hence has the potential of monitoring cancer treatment. Ultrasound contrast agents have also been shown to enhance contrast between blood and the surrounding tissue and hence may be used to distinguish between treated and untreated tumours. Theoretical models of high frequency ultrasound scattering from individual cells and ultrasound contrast agents (UCAs) are needed in order to develop methods for using high frequency ultrasound to classify tumours, quantify their responses to treatment, and eventually provide a better cancer detection and treatment monitoring techniques. This work introduces a new technique for measuring the ultrasound backscatter from individual micron-sized objects by combining a microinjection system with a co-registered optical microscope and an ultrasound imaging device. The system was calibrated by measuring the backscatter response from polystyrene microspheres and comparing it to theoretical predictions of an elastic sphere. The backscatter responses from single sea urchin oocytes and acute myloid leukemia cells were also investigated. It was found that such responses are best modelled using the fluid sphere model. A finite element model was also introduced to study scattering from microspheres and UCAs. The Helmholtz equation was used to describe the propagation of sound waves in the fluid domains whereas the constitutive equation was used to describe the stress-strain relationship in the solid domains. Studies on polystyrene microspheres and UCAs revealed the existence of a systematic relationship between the resonance frequencies and the microsphere surface modes. No such a relationship was found for the UCAs of interest. Instead, these agents exhibited a collection of complex oscillations which appear to be a combination of various surface modes. Increasing the UCA's shell thickness and its shear modulus produced a shift in the resonance frequencies to higher values. A decrease in UCA diameter produced similar effects. The importance of these findings towards the understanding of the UCA behaviour at high frequencies and the generation of harmonics are discussed. Future work includes the measurement of the backscatter response from individual UCAs and cells at various apoptotic stages.

1448: Effects of High Frequency Ultrasound on Echogenicity of Ultrasound Contrast Agents Solutions

Ultrasound in Medicine & Biology ◽

10.1016/j.ultrasmedbio.2009.06.834 ◽

2009 ◽

Vol 35 (8) ◽

pp. S221

Author(s):

Marcello Mancini ◽

Antonio Speranza ◽

Adelaide Greco ◽

Marco Salvatore

Keyword(s):

Contrast Agents ◽

High Frequency ◽

Ultrasound Contrast ◽

Modelling high frequency ultrasound scattering from cells and ultrasound contrast agents

10.32920/ryerson.14658069 ◽

2021 ◽

Author(s):

Omar Falou

Keyword(s):

Contrast Agents ◽

High Frequency ◽

Polystyrene Microspheres ◽

Surface Modes ◽

Ultrasound Contrast ◽

Resonance Frequencies ◽

Ultrasound Scattering ◽

High frequency ultrasound has been shown to detect structural and physical changes in cell ensembles during apoptosis and hence has the potential of monitoring cancer treatment. Ultrasound contrast agents have also been shown to enhance contrast between blood and the surrounding tissue and hence may be used to distinguish between treated and untreated tumours. Theoretical models of high frequency ultrasound scattering from individual cells and ultrasound contrast agents (UCAs) are needed in order to develop methods for using high frequency ultrasound to classify tumours, quantify their responses to treatment, and eventually provide a better cancer detection and treatment monitoring techniques. This work introduces a new technique for measuring the ultrasound backscatter from individual micron-sized objects by combining a microinjection system with a co-registered optical microscope and an ultrasound imaging device. The system was calibrated by measuring the backscatter response from polystyrene microspheres and comparing it to theoretical predictions of an elastic sphere. The backscatter responses from single sea urchin oocytes and acute myloid leukemia cells were also investigated. It was found that such responses are best modelled using the fluid sphere model. A finite element model was also introduced to study scattering from microspheres and UCAs. The Helmholtz equation was used to describe the propagation of sound waves in the fluid domains whereas the constitutive equation was used to describe the stress-strain relationship in the solid domains. Studies on polystyrene microspheres and UCAs revealed the existence of a systematic relationship between the resonance frequencies and the microsphere surface modes. No such a relationship was found for the UCAs of interest. Instead, these agents exhibited a collection of complex oscillations which appear to be a combination of various surface modes. Increasing the UCA's shell thickness and its shear modulus produced a shift in the resonance frequencies to higher values. A decrease in UCA diameter produced similar effects. The importance of these findings towards the understanding of the UCA behaviour at high frequencies and the generation of harmonics are discussed. Future work includes the measurement of the backscatter response from individual UCAs and cells at various apoptotic stages.

Recent Experiences and Advances in Contrast-Enhanced Subharmonic Ultrasound

BioMed Research International ◽

10.1155/2015/640397 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 9

Author(s):

John R. Eisenbrey ◽

Anush Sridharan ◽

Ji-Bin Liu ◽

Flemming Forsberg

Keyword(s):

Contrast Agents ◽

Tumor Imaging ◽

Three Dimensional ◽

Surrounding Tissue ◽

Contrast Enhanced Ultrasound ◽

Ultrasound Contrast ◽

Contrast Enhanced ◽

Subharmonic Response

Nonlinear contrast-enhanced ultrasound imaging schemes strive to suppress tissue signals in order to better visualize nonlinear signals from blood-pooling ultrasound contrast agents. Because tissue does not generate a subharmonic response (i.e., signal at half the transmit frequency), subharmonic imaging has been proposed as a method for isolating ultrasound microbubble signals while suppressing surrounding tissue signals. In this paper, we summarize recent advances in the use of subharmonic imagingin vivo. These advances include the implementation of subharmonic imaging on linear and curvilinear arrays, intravascular probes, and three-dimensional probes for breast, renal, liver, plaque, and tumor imaging.

In Vitro Volume Imaging of Articular Cartilage Using Chirp-Coded High Frequency Ultrasound

2018 IEEE International Ultrasonics Symposium (IUS) ◽

10.1109/ultsym.2018.8579673 ◽

2018 ◽

Author(s):

Anowarul Habib ◽

Juha Vierinen ◽

Ashraful Islam ◽

Inigo Zubiavrre Martinez ◽

Frank Melandso

Keyword(s):

Articular Cartilage ◽

High Frequency ◽

Volume Imaging ◽

Development in High Frequency Ultrasonic Imaging and Transducers

Nondestructive Engineering: Applications ◽

10.1115/pvp2002-1632 ◽

2002 ◽

Author(s):

K. Kirk Shung

Keyword(s):

High Frequency ◽

Ultrasonic Imaging ◽

Piezoelectric Element ◽

Large Degree ◽

Imaging Systems ◽

High Frequencies ◽

Recent Developments ◽

Supporting Structures ◽

There has been intense interest recently in ultrasonic imaging in the frequency range from 20 MHz and beyond in biomedicine. High frequency ultrasound has applications in dermatology, ophthalmology and intravascular imaging because of its superior resolution. The performance of ultrasonic imaging systems especially at high frequencies depends critically upon the transducers/arrays, the design of which in turn is determined to a large degree by the materials and fabrication methodology of the piezoelectric element and supporting structures. Recent developments in these areas are discussed in this paper.