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Stephens DN, Mahmoud AM, Ding X, Lucero S, Dutta D, Yu FT, Chen X, Kim K. Flexible integration of high-imaging-resolution and high-power arrays for ultrasound-induced thermal strain imaging (US-TSI). IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:2645-56. [PMID: 24297029 PMCID: PMC3857565 DOI: 10.1109/tuffc.2013.2863] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ultrasound-induced thermal strain imaging (USTSI) for carotid artery plaque detection requires both high imaging resolution (<100 μm) and sufficient US-induced heating to elevate the tissue temperature (~1°C to 3°C within 1 to 3 cardiac cycles) to produce a noticeable change in sound speed in the targeted tissues. Because the optimization of both imaging and heating in a monolithic array design is particularly expensive and inflexible, a new integrated approach is presented which utilizes independent ultrasound arrays to meet the requirements for this particular application. This work demonstrates a new approach in dual-array construction. A 3-D printed manifold was built to support both a high-resolution 20 MHz commercial imaging array and 6 custom heating elements operating in the 3.5 to 4 MHz range. For the application of US-TSI in carotid plaque characterization, the tissue target site is 20 to 30 mm deep, with a typical target volume of 2 mm (elevation) × 8 mm (azimuthal) × 5 mm (depth). The custom heating array performance was fully characterized for two design variants (flat and spherical apertures), and can easily deliver 30 W of total acoustic power to produce intensities greater than 15 W/cm(2) in the tissue target region.
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Affiliation(s)
| | - Ahmed M. Mahmoud
- Center for Ultrasound Molecular Imaging and Therapeutics-Department of Medicine and Heart and Vascular Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center
- Department of Biomedical Engineering and Systems, Cairo University, Egypt
| | - Xuan Ding
- Center for Ultrasound Molecular Imaging and Therapeutics-Department of Medicine and Heart and Vascular Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center
- Department of Bioengineering, University of Pittsburgh School of Engineering
| | | | - Debaditya Dutta
- Center for Ultrasound Molecular Imaging and Therapeutics-Department of Medicine and Heart and Vascular Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center
| | - Francois T.H. Yu
- Center for Ultrasound Molecular Imaging and Therapeutics-Department of Medicine and Heart and Vascular Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center
| | - Xucai Chen
- Center for Ultrasound Molecular Imaging and Therapeutics-Department of Medicine and Heart and Vascular Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center
| | - Kang Kim
- Center for Ultrasound Molecular Imaging and Therapeutics-Department of Medicine and Heart and Vascular Institute, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center
- Department of Bioengineering, University of Pittsburgh School of Engineering
- McGowan Institute for Regenerative Medicine, University of Pittsburgh and University of Pittsburgh Medical Center
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Lai CY, Fite BZ, Ferrara KW. Ultrasonic enhancement of drug penetration in solid tumors. Front Oncol 2013; 3:204. [PMID: 23967400 PMCID: PMC3746679 DOI: 10.3389/fonc.2013.00204] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 07/25/2013] [Indexed: 12/22/2022] Open
Abstract
Increasing the penetration of drugs within solid tumors can be accomplished through multiple ultrasound-mediated mechanisms. The application of ultrasound can directly change the structure or physiology of tissues or can induce changes in a drug or vehicle in order to enhance delivery and efficacy. With each ultrasonic pulse, a fraction of the energy in the propagating wave is absorbed by tissue and results in local heating. When ultrasound is applied to achieve mild hyperthermia, the thermal effects are associated with an increase in perfusion or the release of a drug from a temperature-sensitive vehicle. Higher ultrasound intensities locally ablate tissue and result in increased drug accumulation surrounding the ablated region of interest. Further, the mechanical displacement induced by the ultrasound pulse can result in the nucleation, growth and collapse of gas bubbles. As a result of such cavitation, the permeability of a vessel wall or cell membrane can be increased. Finally, the radiation pressure of the propagating pulse can translate particles or tissues. In this perspective, we will review recent progress in ultrasound-mediated tumor delivery and the opportunities for clinical translation.
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Affiliation(s)
- Chun-Yen Lai
- Department of Biomedical Engineering, University of California Davis , Davis, CA , USA
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Fite BZ, Liu Y, Kruse DE, Caskey CF, Walton JH, Lai CY, Mahakian LM, Larrat B, Dumont E, Ferrara KW. Magnetic resonance thermometry at 7T for real-time monitoring and correction of ultrasound induced mild hyperthermia. PLoS One 2012; 7:e35509. [PMID: 22536396 PMCID: PMC3335017 DOI: 10.1371/journal.pone.0035509] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 03/16/2012] [Indexed: 12/30/2022] Open
Abstract
While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (≥7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition. An MRgFUS system capable of delivering a controlled 3D acoustic dose during real time MRT with proportional, integral, and derivative (PID) feedback control was developed and validated. Real-time MRT was validated in a tofu phantom with fluoroptic temperature measurements, and acoustic heating simulations were in good agreement with MR temperature maps. In an in vivo Met-1 mouse tumor, the real-time PID feedback control is capable of maintaining the desired temperature with high accuracy. We found that real time MR control of hyperthermia is feasible at high field, and k-space based PPI techniques may be implemented for increasing temporal resolution while maintaining temperature accuracy on the order of 1°C.
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Affiliation(s)
- Brett Z. Fite
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
- Biophysics Graduate Group, University of California, Davis, Davis, California, United States of America
| | - Yu Liu
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
| | - Dustin E. Kruse
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
| | - Charles F. Caskey
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
| | - Jeffrey H. Walton
- NMR Facility and Biomedical Engineering Graduate Group, University of California, Davis, Davis, California, United States of America
| | - Chun-Yen Lai
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
| | - Lisa M. Mahakian
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
| | - Benoit Larrat
- Institut Langevin, ESPCI Paristech, CNRS UMR7589, INSERM, Paris, France
| | | | - Katherine W. Ferrara
- Department of Biomedical Engineering, University of California, Davis, Davis, California, United States of America
- * E-mail:
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Stephens D, Kruse D, Qin S, Ferrara K. Design aspects of focal beams from high-intensity arrays. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2011; 58:1590-602. [PMID: 21859578 PMCID: PMC3174850 DOI: 10.1109/tuffc.2011.1986] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
As the applications of ultrasonic thermal therapies expand, the design of the high-intensity array must address both the energy delivery of the main beam and the character and relevance of off-target beam energy. We simulate the acoustic field performance of a selected set of circular arrays organized by array format, including flat versus curved arrays, periodic versus random arrays, and center void diameter variations. Performance metrics are based on the -3-dB focal main lobe (FML) positioning range, axial grating lobe (AGL) temperatures, and side lobe levels. Using finite-element analysis, we evaluate the relative heating of the FML and the AGLs. All arrays have a maximum diameter of 100λ, with element count ranging from 64 to 1024 and continuous wave frequency of 1.5 MHz. First, we show that a 50% spherical annulus produces focus beam side lobes which decay as a function of lateral distance at nearly 87% of the exponential rate of a full aperture. Second, for the arrays studied, the efficiency of power delivery over the -3-dB focus positioning range for spherical arrays is at least 2-fold greater than for flat arrays; the 256-element case shows a 5-fold advantage for the spherical array. Third, AGL heating can be significant as the focal target is moved to its distal half-intensity depth from the natural focus. Increasing the element count of a randomized array to 256 elements decreases the AGL-to-FML heating ratio to 0.12 at the distal half-intensity depth. Further increases in element count yield modest improvements. A 49% improvement in the AGL-to-peak heating ratio is predicted by using the Sumanaweera spiral element pattern with randomization.
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