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Mondou P, Mériaux S, Nageotte F, Vappou J, Novell A, Larrat B. State of the art on microbubble cavitation monitoring and feedback control for blood-brain-barrier opening using focused ultrasound. Phys Med Biol 2023; 68:18TR03. [PMID: 37369229 DOI: 10.1088/1361-6560/ace23e] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/27/2023] [Indexed: 06/29/2023]
Abstract
Focused ultrasound (FUS) is a non-invasive and highly promising method for targeted and reversible blood-brain barrier permeabilization. Numerous preclinical studies aim to optimize the localized delivery of drugs using this method in rodents and non-human primates. Several clinical trials have been initiated to treat various brain diseases in humans using simultaneous BBB permeabilization and drug injection. This review presents the state of the art ofin vitroandin vivocavitation control algorithms for BBB permeabilization using microbubbles (MB) and FUS. Firstly, we describe the different cavitation states, their physical significance in terms of MB behavior and their translation into the spectral composition of the backscattered signal. Next, we report the different indexes calculated and used during the ultrasonic monitoring of cavitation. Finally, the differentin vitroandin vivocavitation control strategies described in the literature are presented and compared.
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Affiliation(s)
- Paul Mondou
- Université de Strasbourg, CNRS, ICube, UMR7357, Strasbourg, France
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
| | - Sébastien Mériaux
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
| | - Florent Nageotte
- Université de Strasbourg, CNRS, ICube, UMR7357, Strasbourg, France
| | - Jonathan Vappou
- Université de Strasbourg, CNRS, ICube, UMR7357, Strasbourg, France
| | - Anthony Novell
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, SHFJ, 91401 , Orsay, France
| | - Benoit Larrat
- Université Paris-Saclay, CEA, CNRS, BAOBAB, NeuroSpin, 91191, Gif-sur-Yvette, France
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2
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Sojahrood AJ, Haghi H, Karshafian R, Kolios MC. Nonlinear dynamics and bifurcation structure of ultrasonically excited lipid coated microbubbles. ULTRASONICS SONOCHEMISTRY 2021; 72:105405. [PMID: 33360533 PMCID: PMC7803687 DOI: 10.1016/j.ultsonch.2020.105405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/08/2020] [Accepted: 11/09/2020] [Indexed: 05/04/2023]
Abstract
In many applications, microbubbles (MBs) are encapsulated by a lipid coating to increase their stability. However, the complex behavior of the lipid coating including buckling and rupture sophisticates the dynamics of the MBs and as a result the dynamics of the lipid coated MBs (LCMBs) are not well understood. Here, we investigate the nonlinear behavior of the LCMBs by analyzing their bifurcation structure as a function of acoustic pressure. We show that, the LC can enhance the generation of period 2 (P2), P3, higher order subharmonics (SH), superharmonics and chaos at very low excitation pressures (e.g. 1 kPa). For LCMBs sonicated by their SH resonance frequency and in line with experimental observations with increasing pressure, P2 oscillations exhibit three stages: generation at low acoustic pressures, disappearance and re-generation. Within non-destructive oscillation regimes and by pressure amplitude increase, LCMBs can also exhibit two saddle node (SN) bifurcations resulting in possible abrupt enhancement of the scattered pressure. The first SN resembles the pressure dependent resonance phenomenon in uncoated MBs and the second SN resembles the pressure dependent SH resonance. Depending on the initial surface tension of the LCMBs, the nonlinear behavior may also be suppressed for a wide range of excitation pressures.
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Affiliation(s)
- A J Sojahrood
- Department of Physics, Ryerson University, Toronto, Canada; Institute for Biomedical Engineering, Science and Technology (IBEST) a partnership between Ryerson University and St. Michael's Hospital, Toronto, Ontario, Canada.
| | - H Haghi
- Department of Physics, Ryerson University, Toronto, Canada; Institute for Biomedical Engineering, Science and Technology (IBEST) a partnership between Ryerson University and St. Michael's Hospital, Toronto, Ontario, Canada
| | - R Karshafian
- Department of Physics, Ryerson University, Toronto, Canada; Institute for Biomedical Engineering, Science and Technology (IBEST) a partnership between Ryerson University and St. Michael's Hospital, Toronto, Ontario, Canada
| | - M C Kolios
- Department of Physics, Ryerson University, Toronto, Canada; Institute for Biomedical Engineering, Science and Technology (IBEST) a partnership between Ryerson University and St. Michael's Hospital, Toronto, Ontario, Canada
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3
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Frinking P, Segers T, Luan Y, Tranquart F. Three Decades of Ultrasound Contrast Agents: A Review of the Past, Present and Future Improvements. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:892-908. [PMID: 31941587 DOI: 10.1016/j.ultrasmedbio.2019.12.008] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 06/10/2023]
Abstract
Initial reports from the 1960s describing the observations of ultrasound contrast enhancement by tiny gaseous bubbles during echocardiographic examinations prompted the development of the first ultrasound contrast agent in the 1980s. Current commercial contrast agents for echography, such as Definity, Optison, Sonazoid and SonoVue, have proven to be successful in a variety of on- and off-label clinical indications. Whereas contrast-specific technology has seen dramatic progress after the introduction of the first approved agents in the 1990s, successful clinical translation of new developments has been limited during the same period, while understanding of microbubble physical, chemical and biologic behavior has improved substantially. It is expected that for a successful development of future opportunities, such as ultrasound molecular imaging and therapeutic applications using microbubbles, new creative developments in microbubble engineering and production dedicated to further optimizing microbubble performance are required, and that they cannot rely on bubble technology developed more than 3 decades ago.
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Affiliation(s)
- Peter Frinking
- Tide Microfluidics, Capitool 41, Enschede, The Netherlands.
| | - Tim Segers
- Physics of Fluids group, University of Twente, Enschede, The Netherlands
| | - Ying Luan
- R&D Pharmaceutical Diagnostics, General Electric Healthcare, Amersham, UK
| | - François Tranquart
- R&D Pharmaceutical Diagnostics, General Electric Healthcare, Amersham, UK
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Deng L, O'Reilly MA, Jones RM, An R, Hynynen K. A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping. Phys Med Biol 2016; 61:8476-8501. [PMID: 27845920 DOI: 10.1088/0031-9155/61/24/8476] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Focused ultrasound (FUS) phased arrays show promise for non-invasive brain therapy. However, the majority of them are limited to a single transmit/receive frequency and therefore lack the versatility to expose and monitor the treatment volume. Multi-frequency arrays could offer variable transmit focal sizes under a fixed aperture, and detect different spectral content on receive for imaging purposes. Here, a three-frequency (306, 612, and 1224 kHz) sparse hemispherical ultrasound phased array (31.8 cm aperture; 128 transducer modules) was constructed and evaluated for microbubble-mediated transcranial therapy and simultaneous cavitation mapping. The array is able to perform effective electronic beam steering over a volume spanning (-40, 40) and (-30, 50) mm in the lateral and axial directions, respectively. The focal size at the geometric center is approximately 0.9 (2.1) mm, 1.7 (3.9) mm, and 3.1 (6.5) mm in lateral (axial) pressure full width at half maximum (FWHM) at 1224, 612, and 306 kHz, respectively. The array was also found capable of dual-frequency excitation and simultaneous multi-foci sonication, which enables the future exploration of more complex exposure strategies. Passive acoustic mapping of dilute microbubble clouds demonstrated that the point spread function of the receive array has a lateral (axial) intensity FWHM between 0.8-3.5 mm (1.7-11.7 mm) over a volume spanning (-25, 25) mm in both the lateral and axial directions, depending on the transmit/receive frequency combination and the imaging location. The device enabled both half and second harmonic imaging through the intact skull, which may be useful for improving the contrast-to-tissue ratio or imaging resolution, respectively. Preliminary in vivo experiments demonstrated the system's ability to induce blood-brain barrier opening and simultaneously spatially map microbubble cavitation activity in a rat model. This work presents a tool to investigate optimal strategies for non-thermal FUS brain therapy and concurrent microbubble cavitation monitoring through the availability of multiple frequencies.
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Affiliation(s)
- Lulu Deng
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
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5
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Lindsey BD, Rojas JD, Dayton PA. On the relationship between microbubble fragmentation, deflation and broadband superharmonic signal production. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:1711-25. [PMID: 25766572 PMCID: PMC4778426 DOI: 10.1016/j.ultrasmedbio.2014.12.668] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 12/18/2014] [Accepted: 12/20/2014] [Indexed: 05/19/2023]
Abstract
Acoustic angiography imaging of microbubble contrast agents uses the superharmonic energy produced from excited microbubbles and enables high-contrast, high-resolution imaging. However, the exact mechanism by which broadband harmonic energy is produced is not fully understood. To elucidate the role of microbubble shell fragmentation in superharmonic signal production, simultaneous optical and acoustic measurements were performed on individual microbubbles at transmit frequencies from 1.75 to 3.75 MHz and pressures near the shell fragmentation threshold for microbubbles of varying diameter. High-amplitude, broadband superharmonic signals were produced with shell fragmentation, whereas weaker signals (approximately 25% of peak amplitude) were observed in the presence of shrinking bubbles. Furthermore, when populations of stationary microbubbles were imaged with a dual-frequency ultrasound imaging system, a sharper decline in image intensity with respect to frame number was observed for 1-μm bubbles than for 4-μm bubbles. Finally, in a study of two rodents, increasing frame rate from 4 to 7 Hz resulted in decreases in mean steady-state image intensity of 27% at 1000 kPa and 29% at 1300 kPa. Although the existence of superharmonic signals when bubbles shrink has the potential to prolong the imaging efficacy of microbubbles, parameters such as frame rate and peak pressure must be balanced with expected re-perfusion rate to maintain adequate contrast during in vivo imaging.
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Affiliation(s)
- Brooks D Lindsey
- Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill and North Carolina State University, Raleigh, North Carolina, USA
| | - Juan D Rojas
- Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill and North Carolina State University, Raleigh, North Carolina, USA
| | - Paul A Dayton
- Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill and North Carolina State University, Raleigh, North Carolina, USA.
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6
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Gruber MJ, Bader KB, Holland CK. Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 135:646-53. [PMID: 25234874 PMCID: PMC3986017 DOI: 10.1121/1.4843175] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity(®)) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540-900 kHz) and a broad frequency bandwidth (0.54-1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle.
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Affiliation(s)
- Matthew J Gruber
- Biomedical Engineering Program, University of Cincinnati, Cardiovascular Center 3941, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586
| | - Kenneth B Bader
- Department of Internal Medicine, Division of Cardiovascular Health and Diseases, University of Cincinnati, Cardiovascular Center 3941, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586
| | - Christy K Holland
- Department of Internal Medicine, Division of Cardiovascular Health and Diseases, University of Cincinnati, Cardiovascular Center 3941, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586
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7
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Radhakrishnan K, Bader KB, Haworth KJ, Kopechek JA, Raymond JL, Huang SL, McPherson DD, Holland CK. Relationship between cavitation and loss of echogenicity from ultrasound contrast agents. Phys Med Biol 2013; 58:6541-63. [PMID: 24002637 PMCID: PMC4170692 DOI: 10.1088/0031-9155/58/18/6541] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ultrasound contrast agents (UCAs) have the potential to nucleate cavitation and promote both beneficial and deleterious bioeffects in vivo. Previous studies have elucidated the pulse-duration-dependent pressure amplitude threshold for rapid loss of echogenicity due to UCA fragmentation. Previous studies have demonstrated that UCA fragmentation was concomitant with inertial cavitation. The purpose of this study was to evaluate the relationship between stable and inertial cavitation thresholds and loss of echogenicity of UCAs as a function of pulse duration. Determining the relationship between cavitation thresholds and loss of echogenicity of UCAs would enable monitoring of cavitation based upon the onscreen echogenicity in clinical applications. Two lipid-shelled UCAs, echogenic liposomes (ELIP) and Definity®, were insonified by a clinical ultrasound scanner in duplex spectral Doppler mode at four pulse durations ('sample volumes') in both a static system and a flow system. Cavitation emissions from the UCAs insonified by Doppler pulses were recorded using a passive cavitation detection system and stable and inertial cavitation thresholds ascertained. Loss of echogenicity from ELIP and Definity® was assessed within regions of interest on B-mode images. A numerical model based on UCA rupture predicted the functional form of the loss of echogenicity from ELIP and Definity®. Stable and inertial cavitation thresholds were found to have a weak dependence on pulse duration. Stable cavitation thresholds were lower than inertial cavitation thresholds. The power of cavitation emissions was an exponential function of the loss of echogenicity over the investigated range of acoustic pressures. Both ELIP and Definity® lost more than 80% echogenicity before the onset of stable or inertial cavitation. Once this level of echogenicity loss occurred, both stable and inertial cavitation were detected in the physiologic flow phantom. These results imply that stable and inertial cavitation are necessary in order to trigger complete loss of echogenicity acoustically from UCAs and this finding can be used when planning diagnostic and therapeutic applications.
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8
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Novell A, Escoffre JM, Bouakaz A. Second harmonic and subharmonic for non-linear wideband contrast imaging using a capacitive micromachined ultrasonic transducer array. ULTRASOUND IN MEDICINE & BIOLOGY 2013; 39:1500-12. [PMID: 23743105 DOI: 10.1016/j.ultrasmedbio.2013.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 02/25/2013] [Accepted: 03/03/2013] [Indexed: 05/22/2023]
Abstract
When insonified with suitable ultrasound excitation, contrast microbubbles generate various non-linear scattered components, such as the second harmonic (2H) and the subharmonic (SH). In this study, we exploit the wide frequency bandwidth of capacitive micromachined ultrasonic transducers (CMUTs) to enhance the response from ultrasound contrast agents by selective imaging of both the 2H and SH components simultaneously. To this end, contrast images using the pulse inversion method were recorded with a 64-element CMUT linear array connected to an open scanner. In comparison to imaging at 2H alone, the wideband imaging including both the 2H and SH contributions provided up to 130% and 180% increases in the signal-to-noise and contrast-to-tissue ratios, respectively. The wide-frequency band of CMUTs offers new opportunities for improved ultrasound contrast agent imaging.
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Affiliation(s)
- Anthony Novell
- UMR Inserm U 930, Université François-Rabelais de Tours, PRES Centre-Val de Loire Université, Tours, France
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9
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Pitt WG, Husseini GA, Kherbeck LN. Ultrasound-triggered Release from Micelles. SMART MATERIALS FOR DRUG DELIVERY 2013. [DOI: 10.1039/9781849736800-00148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Ultrasound is an ideal trigger for site-actuated drug delivery because it can be focused through the skin to internal targets without surgery. Thermal or mechanical energy can be delivered via tissue heating or bubble cavitation, respectively. Bubble cavitation, which concentrates energy that can trigger drug release from carriers, occurs more readily at low frequencies and at bubble resonant frequencies. Other mechanical and physical consequences of cavitation are reviewed. Micelles are nanosized molecular assemblies of amphiphilic molecules that spontaneously form in aqueous solution and possess a hydrophobic core capable of sequestering hydrophobic drugs. Micelles have traditionally been used to increase the solubility of hydrophobic therapeutics for oral and intravenous administration. For ultrasonic drug delivery, polymeric micelles containing polyethylene oxide blocks are preferred because they have longer circulation time in vivo. Passive delivery occurs when micelles accumulate in tumor tissues that have malformed capillaries with porous walls. In active delivery targeting ligands are attached to the micelles, which directs their binding to specific cells. Actuated delivery occurs when ultrasound causes drug release from micelles and is attributed to bubble cavitation since the amount released correlates with acoustic signatures of cavitation. The mechanisms of ultrasonic drug release are discussed, including the prevalent theory that gas bubble cavitation events create high shear stress and shock waves that transiently perturb the structure of the micelles and allow drug to escape from the hydrophobic core. Ultrasound also perturbs cell membranes, rendering them more permeable to drug uptake. Tumors in rats and mice have been successfully treated using low-frequency ultrasound and chemotherapeutics in polymeric micelles. Ultrasonically activated drug delivery has great clinical potential.
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Affiliation(s)
- William G. Pitt
- Chemical Engineering Department Brigham Young University, Provo, UT84602 USA
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10
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Dave JK, Halldorsdottir VG, Eisenbrey JR, Merton DA, Liu JB, Machado P, Zhao H, Park S, Dianis S, Chalek CL, Thomenius KE, Brown DB, Forsberg F. On the implementation of an automated acoustic output optimization algorithm for subharmonic aided pressure estimation. ULTRASONICS 2013; 53:880-8. [PMID: 23347593 PMCID: PMC3595343 DOI: 10.1016/j.ultras.2012.12.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/20/2012] [Accepted: 12/20/2012] [Indexed: 05/04/2023]
Abstract
Incident acoustic output (IAO) dependent subharmonic signal amplitudes from ultrasound contrast agents can be categorized into occurrence, growth or saturation stages. Subharmonic aided pressure estimation (SHAPE) is a technique that utilizes growth stage subharmonic signal amplitudes for hydrostatic pressure estimation. In this study, we developed an automated IAO optimization algorithm to identify the IAO level eliciting growth stage subharmonic signals and also studied the effect of pulse length on SHAPE. This approach may help eliminate the problems of acquiring and analyzing the data offline at all IAO levels as was done in previous studies and thus, pave the way for real-time clinical pressure monitoring applications. The IAO optimization algorithm was implemented on a Logiq 9 (GE Healthcare, Milwaukee, WI) scanner interfaced with a computer. The optimization algorithm stepped the ultrasound scanner from 0% to 100% IAO. A logistic equation fitting function was applied with the criterion of minimum least squared error between the fitted subharmonic amplitudes and the measured subharmonic amplitudes as a function of the IAO levels and the optimum IAO level was chosen corresponding to the inflection point calculated from the fitted data. The efficacy of the optimum IAO level was investigated for in vivo SHAPE to monitor portal vein (PV) pressures in 5 canines and was compared with the performance of IAO levels, below and above the optimum IAO level, for 4, 8 and 16 transmit cycles. The canines received a continuous infusion of Sonazoid microbubbles (1.5 μl/kg/min; GE Healthcare, Oslo, Norway). PV pressures were obtained using a surgically introduced pressure catheter (Millar Instruments, Inc., Houston, TX) and were recorded before and after increasing PV pressures. The experiments showed that optimum IAO levels for SHAPE in the canines ranged from 6% to 40%. The best correlation between changes in PV pressures and in subharmonic amplitudes (r=-0.76; p=0.24), and between the absolute PV pressures and the subharmonic amplitudes (r=-0.89; p<0.01) were obtained for the optimized IAO and 4 transmit cycles. Only for the optimized IAO and 4 transmit cycles did the subharmonic amplitudes differ significantly (p<0.01) before and after increasing PV pressures. A new algorithm to identify optimum IAO levels for SHAPE has been developed and validated with the best results being obtained for 4 transmit cycles. The work presented in this study may pave the way for real-time clinical applications of estimating pressures using the subharmonic signals from ultrasound contrast agents.
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Affiliation(s)
- J K Dave
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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11
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Díaz de la Rosa MA, Husseini GA, Pitt WG. Mathematical modeling of microbubble cavitation at 70 kHz and the importance of the subharmonic in drug delivery from micelles. ULTRASONICS 2013; 53:97-110. [PMID: 22739406 DOI: 10.1016/j.ultras.2012.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 04/04/2012] [Accepted: 04/15/2012] [Indexed: 06/01/2023]
Abstract
In order to gain insight into the experimental observation of ultrasound-induced release of drugs from micelles, we modeled the dynamic oscillations of a 10-μm-diameter bubble insonated at 70kHz. The Parlitz modification of the Keller-Miksis model was employed to generate bubble dynamics over a wide range of mechanical index values. The resulting Poincaré maps and bifurcation diagram show that bubble oscillations bifurcate at a MI value of 0.32, then return apparently to a single mode before displaying a sudden onset of chaotic behavior at 0.35. The experimental release of drug from micelles occurs at a MI value of 0.37 and correlates with the intensity of the subharmonic in (μW/cm(2)) of the acoustic spectrum. The dynamic model shows the return to single mode at a MI value of 0.43, and bifurcation leading to chaos at values above 0.5. The correlation between the chaotic behavior predicted by the model and drug release hints at insonation conditions that could facilitate drug delivery.
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Affiliation(s)
- Mario A Díaz de la Rosa
- Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, United States
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12
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Dave JK, Halldorsdottir VG, Eisenbrey JR, Merton DA, Liu JB, Zhou JH, Wang HK, Park S, Dianis S, Chalek CL, Lin F, Thomenius KE, Brown DB, Forsberg F. Investigating the efficacy of subharmonic aided pressure estimation for portal vein pressures and portal hypertension monitoring. ULTRASOUND IN MEDICINE & BIOLOGY 2012; 38:1784-98. [PMID: 22920550 PMCID: PMC3576693 DOI: 10.1016/j.ultrasmedbio.2012.06.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 06/19/2012] [Accepted: 06/29/2012] [Indexed: 05/14/2023]
Abstract
The efficacy of using subharmonic emissions from Sonazoid microbubbles (GE Healthcare, Oslo, Norway) to track portal vein pressures and pressure changes was investigated in 14 canines using either slow- or high-flow models of portal hypertension (PH). A modified Logiq 9 scanner (GE Healthcare, Milwaukee, WI, USA) operating in subharmonic mode (f(transmit): 2.5 MHz, f(receive): 1.25 MHz) was used to collect radiofrequency data at 10-40% incident acoustic power levels with 2-4 transmit cycles (in triplicate) before and after inducing PH. A pressure catheter (Millar Instruments, Inc., Houston, TX, USA) provided reference portal vein pressures. At optimum insonification, subharmonic signal amplitude changes correlated with portal vein pressure changes; r ranged from -0.82 to -0.94 and from -0.70 to -0.73 for PH models considered separately or together, respectively. The subharmonic signal amplitudes correlated with absolute portal vein pressures (r: -0.71 to -0.79). Statistically significant differences between subharmonic amplitudes, before and after inducing PH, were noted (p ≤ 0.01). Portal vein pressures estimated using subharmonic aided pressure estimation did not reveal significant differences (p > 0.05) with respect to the pressures obtained using the Millar pressure catheter. Subharmonic-aided pressure estimation may be useful clinically for portal vein pressure monitoring.
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Affiliation(s)
- Jaydev K. Dave
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - Valgerdur G. Halldorsdottir
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - John R. Eisenbrey
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Daniel A. Merton
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Ji-Bin Liu
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Jian-Hua Zhou
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Hsin-Kai Wang
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | | | | | - Feng Lin
- GE Global Research, Niskayuna NY 12309, USA
| | | | - Daniel B. Brown
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Flemming Forsberg
- Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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13
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Faez T, Emmer M, Docter M, Sijl J, Versluis M, de Jong N. Characterizing the subharmonic response of phospholipid-coated microbubbles for carotid imaging. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:958-70. [PMID: 21531498 DOI: 10.1016/j.ultrasmedbio.2011.02.017] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 02/22/2011] [Accepted: 02/24/2011] [Indexed: 05/13/2023]
Abstract
The subharmonic vibration of BR14 (Bracco Research S.A., Geneva, Switzerland) contrast agent microbubbles is investigated within the preferable frequency range for carotid ultrasound imaging (8-12 MHz). The response of the bubbles was recorded optically with an ultra-fast recording camera (Brandaris 128) at three acoustic pressures (50, 100 and 120 kPa). The vibration of the microbubbles was measured as a function of the excitation frequency and its frequency content was determined. Among 390 recordings, 40% showed subharmonic oscillations. It was observed that for smaller microbubbles (diameter < 3 μm) the frequency of the maximum subharmonic response increases for increasing pressures (shell hardening) opposite to what has been reported for larger microbubbles (3 μm < diameter < 15 μm). These findings are well predicted by the model proposed by Marmottant et al. (2005) after including the dilatational shell viscosity of the microbubbles measured by Van der Meer et al. (2007), which indicates a marked shear-thinning behavior of the phospholipid shell.
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Affiliation(s)
- Telli Faez
- Biomedical Engineering Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands.
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14
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Sijl J, Dollet B, Overvelde M, Garbin V, Rozendal T, de Jong N, Lohse D, Versluis M. Subharmonic behavior of phospholipid-coated ultrasound contrast agent microbubbles. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2010; 128:3239-52. [PMID: 21110619 DOI: 10.1121/1.3493443] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Coated microbubbles, unlike tissue are able to scatter sound subharmonically. Therefore, the subharmonic behavior of coated microbubbles can be used to enhance the contrast in ultrasound contrast imaging. Theoretically, a threshold amplitude of the driving pressure can be calculated above which subharmonic oscillations of microbubbles are initiated. Interestingly, earlier experimental studies on coated microbubbles demonstrated that the threshold for these bubbles is much lower than predicted by the traditional linear viscoelastic shell models. This paper presents an experimental study on the subharmonic behavior of differently sized individual phospholipid coated microbubbles. The radial subharmonic response of the microbubbles was recorded with the Brandaris ultra high-speed camera as a function of both the amplitude and the frequency of the driving pulse. Threshold pressures for subharmonic generation as low as 5 kPa were found near a driving frequency equal to twice the resonance frequency of the bubble. An explanation for this low threshold pressure is provided by the shell buckling model proposed by Marmottant et al. [J. Acoust. Soc. Am. 118, 3499-3505 (2005)]. It is shown that the change in the elasticity of the bubble shell as a function of bubble radius as proposed in this model, enhances the subharmonic behavior of the microbubbles.
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Affiliation(s)
- Jeroen Sijl
- Physics of Fluids Group and MIRA Institute of Biomedical Engineering and Technical Medicine, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
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15
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Frinking PJA, Brochot J, Arditi M. Subharmonic scattering of phospholipid-shell microbubbles at low acoustic pressure amplitudes. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2010; 57:1762-71. [PMID: 20704062 DOI: 10.1109/tuffc.2010.1614] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Subharmonic scattering of phospholipid-shell microbubbles excited at relatively low acoustic pressure amplitudes (<30 kPa) has been associated with echo responses from compression-only bubbles having initial surface tension values close to zero. In this work, the relation between sbharmonics and compression-only behavior of phospholipid-shell microbubbles was investigated, experimentally and by simulation, as a function of the initial surface tension by applying ambient overpressures of 0 and 180 mmHg. The microbubbles were excited using a 64-cycle transmit burst with a center frequency of 4 MHz and peak-negative pressure amplitudes ranging from 20 of 150 kPa. In these conditions, an increase in subharmonic response of 28.9 dB (P < 0.05) was measured at 50 kPa after applying an overpressure of 180 mmHg. Simulations using the Marmottant model, taking into account the effect of ambient overpressure on bubble size and initial surface tension, confirmed the relation between subharmonics observed in the pressure-time curves and compression-only behavior observed in the radius-time curves. The trend of an increase in subharmonic response as a function of ambient overpressure, i.e., as a function of the initial surface tension, was predicted by the model. Subharmonics present in the echo responses of phospholipid-shell microbubbles excited at low acoustic pressure amplitudes are indeed related to the echo responses from compression-only bubbles. The increase in subharmonics as a function of ambient overpressure may be exploited for improving methods for noninvasive pressure measurement in heart cavities or big vessels in the human body.
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Sboros V, Tang MX. The assessment of microvascular flow and tissue perfusion using ultrasound imaging. Proc Inst Mech Eng H 2010; 224:273-90. [PMID: 20349819 DOI: 10.1243/09544119jeim621] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Imaging microvascular flow is of diagnostic value for a wide range of diseases including cancer, inflammation, and cardiovascular disease. The introduction of microbubbles as ultrasound contrast agents offers significant signal enhancement to the otherwise weakly scattered signal from blood in the circulation. Microbubbles provide maximum impedance mismatch, but are not linear scatterers. Their complex response to ultrasound has generated research on both their behaviour and their scattered-signal processing. Nearly 20 years ago signal processing started with simple spectral filtering of harmonics showing contrast-enhanced images. More recent pulse encoding techniques have achieved good cancellation of tissue echoes. The good quality contrast-only images enabled ultrasound contrast-imaging applications to be established in microvascular measurements in the liver and the myocardium. The field promises to advance the quantification of microvascular flow kinetics.
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Affiliation(s)
- V Sboros
- Medical Physics, University of Edinburgh, Edinburgh, UK.
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17
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Husseini GA, Stevenson-Abouelnasr D, Pitt WG, Assaleh KT, Farahat LO, Fahadi J. Kinetics and Thermodynamics of Acoustic Release of Doxorubicin from Non-stabilized polymeric Micelles. Colloids Surf A Physicochem Eng Asp 2010; 359:18-24. [PMID: 20495608 PMCID: PMC2872131 DOI: 10.1016/j.colsurfa.2010.01.044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This paper studies the thermodynamic characteristics of ultrasound-activated release of Doxorubicin (Dox) from micelles. The release and re-encapsulation of Dox into Pluronic® P105 micelles was measured by recording the fluorescence of a solution of 10 µg/ml Dox and 10% wt P105 polymer in phosphate-buffered saline, during and after insonation by ultrasound at three temperatures, (25 °C, 37 °C and 56 °C). The experimental data were modeled using a previously-published model of the kinetics of the system. The model was simplified by the experimental measurement of one of the parameters, the maximum amount of Dox that can be loaded into the poly(propyleneoxide) cores of the micelles, which was found to be 89 mg/ml PPO and 150 mg Dox/ml PPO at 25 °C and 37 °C, respectively. From the kinetic constants and drug distribution parameters, we deduced the thermodynamic activation energy for micelle re-assembly and the residual activation energies for micelle destruction. Our model showed that the residual activation energy for destruction decreased with increasing acoustic intensity. In addition, higher temperatures were found to encourage micelle destruction and hinder micelle re-assembly.
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Affiliation(s)
- Ghaleb A. Husseini
- Chemical Engineering Department, American University of Sharjah, Sharjah, United Arab Emirates
| | | | - William G. Pitt
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602
| | - Khaled T. Assaleh
- Electrical Engineering Department, American University of Sharjah, Sharjah, United Arab Emirates
| | - Lujein O. Farahat
- Chemical Engineering Department, American University of Sharjah, Sharjah, United Arab Emirates
| | - Jalal Fahadi
- Chemical Engineering Department, American University of Sharjah, Sharjah, United Arab Emirates
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Santin MD, King DA, Foiret J, Haak A, O'Brien WD, Bridal SL. Encapsulated contrast microbubble radial oscillation associated with postexcitation pressure peaks. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2010; 127:1156-64. [PMID: 20136236 PMCID: PMC2852442 DOI: 10.1121/1.3277216] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
This work combines modeling and experiment to assess encapsulated microbubble oscillations associated with broadband pressure peaks detected after microbubble excitation (postexcitation signals). Data were acquired from albumin-shelled and phospholipid-shelled microbubbles using a passive cavitation detector consisting of a confocally aligned 2.8-MHz transmitter and 13-MHz receiver. Microbubbles in weak solutions were insonified with a 5-cycle pulse at a peak rarefactional pressure of 2.0+/-0.2 MPa. For each microbubble type, at least 100 received signals were identified as individual-microbubble responses. The average broadband noise from signals with postexcitation response was 4.2-7.2 dB higher than from signals without postexcitation. Pressure-time responses for each microbubble type were simulated using the model by Marmottant et al. [J. Acoust. Soc. Am. 118, 3499-3505 (2005)], with insonification conditions matching the experiment. Increased broadband noise predicted for microbubbles with postexcitation response was consistent with that observed experimentally (4.0-8.9 dB). The model predicted that postexcitation signals occur only when the radial oscillation exceeds both the shell break-up threshold and twice the initial radius (free bubble inertial cavitation threshold).
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Affiliation(s)
- M D Santin
- UPMC Univ Paris 06, UMR 7623, LIP, F-75005 Paris, France
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Sprague MR, Chérin E, Goertz DE, Foster FS. Nonlinear emission from individual bound microbubbles at high frequencies. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:313-24. [PMID: 20018429 DOI: 10.1016/j.ultrasmedbio.2009.08.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/25/2009] [Accepted: 08/17/2009] [Indexed: 05/21/2023]
Abstract
Targeted microbubbles detected with high-frequency ultrasound can establish the molecular expression of blood vessels with submillimeter resolution. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signal from individual microbubbles were measured as a function of size and pressure. Single phospholipid-shell microbubbles (1.1 to 5.0 microm in diameter) bound to gelatin, co-aligned with an optical microscope and transducer, were insonated with 30 MHz Gaussian-enveloped pulses at pressures from 20 kPa to 1 MPa with -6 dB one-way bandwidths of 11%, 20% and 45%. A subharmonic signal (15 MHz) was detected above a pressure threshold of 110 kPa--independent of bandwidth. The signal peaked for microbubbles 1.60 microm in diameter subject to 20% and 11% bandwidth pulses, and 1.80 microm for 45% bandwidth pulses, for pressures up to 400 kPa, agreeing with the notion that microbubbles insonated at twice their resonant frequency preferentially emit a subharmonic component. For pressures between 400 kPa and 1 MPa, a broader range of microbubbles emitted a subharmonic signal, and microbubbles below 1.70 mum in diameter were disrupted. The second harmonic signal measured, within the limited experimental conditions, was consistent with nonlinear propagation. Further, the results shed light on the effect of the shell on the phase of the subharmonic signal with respect to the fundamental signal.
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Affiliation(s)
- Michael R Sprague
- Department of Medical Biophysics, Sunnybrook Research Institute, University of Toronto, Ontario, Canada
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van Neer PLMJ, Matte G, Danilouchkine MG, Prins C, van den Adel F, de Jong N. Super-harmonic imaging: development of an interleaved phased-array transducer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2010; 57:455-68. [PMID: 20178912 DOI: 10.1109/tuffc.2010.1426] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
For several years, the standard in ultrasound imaging has been second-harmonic imaging. A new imaging technique dubbed "super-harmonic imaging" (SHI) was recently proposed. It takes advantage of the higher - third to fifth - harmonics arising from nonlinear propagation or ultrasound-contrast-agent (UCA) response. Next to its better suppression of near-field artifacts, tissue SHI is expected to improve axial and lateral resolutions resulting in clearer images than second-harmonic imaging. When SHI is used in combination with UCAs, a better contrast-to-tissue ratio can be obtained. The use of SHI implies a large dynamic range and requires a sufficiently sensitive array over a frequency range from the transmission frequency up to its fifth harmonic (bandwidth > 130%). In this paper, we present the characteristics and performance of a new interleaved dual frequency array built chiefly for SHI. We report the rationale behind the design choice, frequencies, aperture, and piezomaterials used. The array is efficient both in transmission and reception with well-behaved transfer functions and a combined -6-dB bandwidth of 144%. In addition, there is virtually no contamination of the harmonic components by spurious transducer transmission, due to low element-to-element crosstalk (< 30 dB) and a low transmission efficiency of the odd harmonics (< 46 dB). The interleaved array presented in this article possesses ideal characteristics for SHI and is suitable for other methods like second-harmonic, subharmonic, and second-order ultrasound field (SURF) imaging.
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Affiliation(s)
- Paul L M J van Neer
- Department of Biomedical Engineering, Erasmus Medical Centre, Rotterdam, The Netherlands.
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Thomas DH, Butler MB, Anderson T, Steel R, Pye SD, Poland M, Brock-Fisher T, McDicken WN, Sboros V. Single microbubble response using pulse sequences: initial results. ULTRASOUND IN MEDICINE & BIOLOGY 2009; 35:112-119. [PMID: 18845380 DOI: 10.1016/j.ultrasmedbio.2008.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 05/26/2008] [Accepted: 07/23/2008] [Indexed: 05/26/2023]
Abstract
The study of acoustic scattering by single microbubbles has the potential to offer improved signal processing techniques. A microacoustic system that employs a hydrodynamically-focused flow was used to detect radiofrequency (RF) backscatter from single microbubbles. RF data were collected using a commercial scanner. Results are presented for two agents, namely Definity (Lantheus Medical Imaging, N. Billerica, MA, USA) and biSphere (Point Biomedical Corp, San Carlos, CA, USA). The agents were insonified with amplitude-modulated pulses, and it was observed in both agents that a subpopulation of microbubbles did not produce a measurable echo from the first-half amplitude pulse, but did produce a response from the full amplitude pulse and from a subsequent half amplitude pulse. The number of microbubbles in this subpopulation was seen to increase with increasing transmit amplitude. These results do not bear out the simple theory of microbubble-pulse sequence interaction and invite a reassessment of signal processing approaches.
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Affiliation(s)
- D H Thomas
- Department of Medical Physics and Medical Engineering, University of Edinburgh, Edinburgh, UK.
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Sboros V. Response of contrast agents to ultrasound. Adv Drug Deliv Rev 2008; 60:1117-36. [PMID: 18486270 DOI: 10.1016/j.addr.2008.03.011] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 03/04/2008] [Indexed: 11/29/2022]
Abstract
Microbubbles are used as ultrasonic contrast agents that enhance the ultrasound signals of the vascular bed. The recent development of site-targeted microbubbles opened up the possibility for molecular imaging as well as localised drug and gene delivery. Initially the microbubbles' physical properties and their response to the ultrasound beam were not fully understood. However, the introduction of fast acquisition microscopy has allowed the observation of the microbubble behaviour in the presence of ultrasound. In addition, acoustical techniques can determine the scatter of single microbubbles. Sonoporation experiments promise high-specificity drug and gene delivery, but the responsible physical mechanisms, particularly for in vivo applications, are not fully understood. An improvement of microbubble technology may address variability related problems in both imaging and drug/gene delivery.
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Affiliation(s)
- Vassilis Sboros
- Medical Physics, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
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