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López-Aguirre M, Castillo-Ortiz M, Viña-González A, Blesa J, Pineda-Pardo JA. The road ahead to successful BBB opening and drug-delivery with focused ultrasound. J Control Release 2024; 372:901-913. [PMID: 38971426 DOI: 10.1016/j.jconrel.2024.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 06/26/2024] [Accepted: 07/03/2024] [Indexed: 07/08/2024]
Abstract
This review delves into the innovative technology of Blood-Brain Barrier (BBB) opening with low-intensity focused ultrasound in combination with microbubbles (LIFU-MB), a promising therapeutic modality aimed at enhancing drug delivery to the central nervous system (CNS). The BBB's selective permeability, while crucial for neuroprotection, significantly hampers the efficacy of pharmacological treatments for CNS disorders. LIFU-MB emerges as a non-invasive and localized method to transiently increase BBB permeability, facilitating the delivery of therapeutic molecules. Here, we review the procedural stages of LIFU-MB interventions, including planning and preparation, sonication, evaluation, and delivery, highlighting the technological diversity and methodological challenges encountered in current clinical applications. With an emphasis on safety and efficacy, we discuss the crucial aspects of ultrasound delivery, microbubble administration, acoustic feedback monitoring and assessment of BBB permeability. Finally, we explore the critical choices for effective BBB opening with LIFU-MB, focusing on selecting therapeutic agents, optimizing delivery methods, and timing for delivery. Overcoming existing barriers to integrate this technology into clinical practice could potentially revolutionize CNS drug delivery and treatment paradigms in the near future.
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Affiliation(s)
- Miguel López-Aguirre
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain; Instituto de Investigación Sanitaria HM Hospitales, Spain; PhD Program in Physics, Complutense University of Madrid, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Castillo-Ortiz
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain; Instituto de Investigación Sanitaria HM Hospitales, Spain; PhD Program in Technologies for Health and Well-being, Polytechnic University of Valencia, Valencia, Spain; Molecular Imaging Technologies Research Institute (I3M), Polytechnic University of Valencia, Valencia, Spain
| | - Ariel Viña-González
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain; Instituto de Investigación Sanitaria HM Hospitales, Spain; PhD Program in Biomedical Engineering, Polytechnic University of Madrid, Madrid, Spain
| | - Javier Blesa
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain; Instituto de Investigación Sanitaria HM Hospitales, Spain; Facultad HM de Ciencias de la Salud de la Universidad Camilo José Cela, Madrid, Spain
| | - José A Pineda-Pardo
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain; Instituto de Investigación Sanitaria HM Hospitales, Spain.
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2
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Hughes A, Khan DS, Alkins R. Current and Emerging Systems for Focused Ultrasound-Mediated Blood-Brain Barrier Opening. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:1479-1490. [PMID: 37100672 DOI: 10.1016/j.ultrasmedbio.2023.02.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/09/2023] [Accepted: 02/23/2023] [Indexed: 05/17/2023]
Abstract
With an ever-growing list of neurological applications of focused ultrasound (FUS), there has been a consequent increase in the variety of systems for delivering ultrasound energy to the brain. Specifically, recent successful pilot clinical trials of blood-brain barrier (BBB) opening with FUS have generated substantial interest in the future applications of this relatively novel therapy, with divergent, purpose-built technologies emerging. With many of these technologies at various stages of pre-clinical and clinical investigation, this article seeks to provide an overview and analysis of the numerous medical devices in active use and under development for FUS-mediated BBB opening.
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Affiliation(s)
- Alec Hughes
- School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Dure S Khan
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada
| | - Ryan Alkins
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada; Division of Neurosurgery, Department of Surgery, Kingston Health Sciences Centre, Queen's University, Kingston, ON, Canada.
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3
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Manuel TJ, Phipps MA, Caskey CF. Design of a 1-MHz Therapeutic Ultrasound Array for Small Volume Blood-Brain Barrier Opening at Cortical Targets in Macaques. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2023; 70:449-459. [PMID: 37028345 DOI: 10.1109/tuffc.2023.3256268] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
[[gabstract]][] Focused ultrasound (FUS) can temporarily open the blood-brain barrier (BBB) and increase the delivery of chemotherapeutics, viral vectors, and other agents to the brain parenchyma. To limit FUS BBB opening to a single brain region, the transcranial acoustic focus of the ultrasound transducer must not be larger than the region targeted. In this work, we design and characterize a therapeutic array optimized for BBB opening at the frontal eye field (FEF) in macaques. We used 115 transcranial simulations in four macaques varying f-number and frequency to optimize the design for focus size, transmission, and small device footprint. The design leverages inward steering for focus tightening, a 1-MHz transmit frequency, and can focus to a simulation predicted 2.5- ± 0.3-mm lateral and 9.5- ± 1.0-mm axial full-width at half-maximum spot size at the FEF without aberration correction. The array is capable of steering axially 35 mm outward, 26 mm inward, and laterally 13 mm with 50% the geometric focus pressure. The simulated design was fabricated, and we characterized the performance of the array using hydrophone beam maps in a water tank and through an ex vivo skull cap to compare measurements with simulation predictions, achieving a 1.8-mm lateral and 9.5-mm axial spot size with a transmission of 37% (transcranial, phase corrected). The transducer produced by this design process is optimized for BBB opening at the FEF in macaques.
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Bao J, Tangney T, Pilitsis JG. Focused Ultrasound for Chronic Pain. Neurosurg Clin N Am 2022; 33:331-338. [DOI: 10.1016/j.nec.2022.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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5
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Saniour I, Robb FJL, Taracila V, Mishra V, Vincent J, Voss HU, Kaplitt MG, Chazen JL, Winkler SA. Characterization of a Low-Profile, Flexible, and Acoustically Transparent Receive-Only MRI Coil Array for High Sensitivity MR-Guided Focused Ultrasound. IEEE ACCESS : PRACTICAL INNOVATIONS, OPEN SOLUTIONS 2022; 10:25062-25072. [PMID: 35600672 PMCID: PMC9119199 DOI: 10.1109/access.2022.3154824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Magnetic resonance guided focused ultrasound (MRgFUS) is a non-invasive therapeutic modality for neurodegenerative diseases that employs real-time imaging and thermometry monitoring of targeted regions. MRI is used in guidance of ultrasound treatment; however, the MR image quality in current clinical applications is poor when using the vendor built-in body coil. We present an 8-channel, ultra-thin, flexible, and acoustically transparent receive-only head coil design (FUS-Flex) to improve the signal-to-noise ratio (SNR) and thus the quality of MR images during MRgFUS procedures. Acoustic simulations/experiments exhibit transparency of the FUS-Flex coil as high as 97% at 650 kHz. Electromagnetic simulations show a SNR increase of 13× over the body coil. In vivo results show an increase of the SNR over the body coil by a factor of 7.3 with 2× acceleration (equivalent to 11× without acceleration) in the brain of a healthy volunteer, which agrees well with simulation. These preliminary results show that the use of a FUS-Flex coil in MRgFUS surgery can increase MR image quality, which could yield improved focal precision, real-time intraprocedural anatomical imaging, and real-time 3D thermometry mapping.
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Affiliation(s)
- Isabelle Saniour
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | | | | | - Vishwas Mishra
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - Jana Vincent
- MR Engineering, GE Healthcare Coils, Aurora, OH 44202, USA
| | - Henning U Voss
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - Michael G Kaplitt
- Department of Neurological Surgery, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - J Levi Chazen
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
| | - Simone Angela Winkler
- Department of Radiology, Weill Cornell Medicine, NewYork-Presbyterian Hospital, New York, NY 10065, USA
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Sugino C, Ruzzene M, Erturk A. Experimental and Computational Investigation of Guided Waves in a Human Skull. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:787-798. [PMID: 33358510 DOI: 10.1016/j.ultrasmedbio.2020.11.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 11/14/2020] [Accepted: 11/17/2020] [Indexed: 06/12/2023]
Abstract
We investigate guided (Lamb) waves in a human cadaver skull through experiments and computational simulations. Ultrasonic wedge transducers and scanning laser Doppler vibrometry are used respectively to excite and measure Lamb waves propagating in the cranial bone of a degassed skull. Measurements are performed over a section of the parietal bone and temporal bone spanning the squamous suture. The experimental data are analyzed for the identification of wave modes and the characterization of dispersion properties. In the parietal bone, for instance, the A0 wave mode is excited between 200 and 600 kHz, and higher-order Lamb waves are excited from 1 to 1.8 MHz. From the experimental dispersion curves and average thickness extracted from the skull computed tomography scan, we estimate average isotropic material properties that capture the essential dispersion characteristics using a semi-analytical finite-element model. We also explore the leaky and non-leaky wave behavior of the degassed skull with water loading in the cranial cavity. Successful excitation of leaky Lamb waves is confirmed (for higher-order wave modes with phase velocity faster than the speed of sound in water) from 500 kHz to 1.5 MHz, which may find applications in imaging and therapeutics at the brain periphery or skull-brain interface (e.g., for metastases). The non-leaky A0 Lamb wave mode propagates between 200 and 600 kHz, with or without fluid loading, for potential use in skull-related diagnostics and imaging (e.g., for sutures).
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Affiliation(s)
- Christopher Sugino
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
| | - Massimo Ruzzene
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado, USA
| | - Alper Erturk
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
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7
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Todd N, McDannold N, Borsook D. Targeted manipulation of pain neural networks: The potential of focused ultrasound for treatment of chronic pain. Neurosci Biobehav Rev 2020; 115:238-250. [PMID: 32534900 PMCID: PMC7483565 DOI: 10.1016/j.neubiorev.2020.06.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/24/2020] [Accepted: 06/04/2020] [Indexed: 12/29/2022]
Abstract
Focused ultrasound (FUS) is a promising technology for facilitating treatment of brain diseases including chronic pain. Focused ultrasound is a unique modality for delivering therapeutic levels of energy into the body, including the central nervous system (CNS). It is non-invasive and can target spatially localized effects through the intact skull to cortical or subcortical regions of the brain. FUS can achieve three different mechanisms of action in the brain that are relevant for chronic pain treatment: (1) localized thermal ablation of neural tissue; (2) localized and transient disruption of the blood-brain barrier for targeted drug delivery to CNS structures; and (3) inhibition or stimulation of neuronal activity in targeted regions. This review provides an in-depth look at the technology of FUS with emphasis placed on applications to CNS-based treatments of chronic pain. While still in the early stages of clinical translation and with some technical challenges remaining, we suggest that FUS has great potential as a novel approach for manipulating CNS networks involved in pain treatment.
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Affiliation(s)
- Nick Todd
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Center for Pain and the Brain, 1 Autumn Street, Boston Children's Hospital, Boston, MA, 02115, United States.
| | - Nathan McDannold
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - David Borsook
- Center for Pain and the Brain, 1 Autumn Street, Boston Children's Hospital, Boston, MA, 02115, United States; Department of Anesthesia, Perioperative, and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, United States
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8
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Wang JB, Di Ianni T, Vyas DB, Huang Z, Park S, Hosseini-Nassab N, Aryal M, Airan RD. Focused Ultrasound for Noninvasive, Focal Pharmacologic Neurointervention. Front Neurosci 2020; 14:675. [PMID: 32760238 PMCID: PMC7372945 DOI: 10.3389/fnins.2020.00675] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 06/02/2020] [Indexed: 12/13/2022] Open
Abstract
A long-standing goal of translational neuroscience is the ability to noninvasively deliver therapeutic agents to specific brain regions with high spatiotemporal resolution. Focused ultrasound (FUS) is an emerging technology that can noninvasively deliver energy up the order of 1 kW/cm2 with millimeter and millisecond resolution to any point in the human brain with Food and Drug Administration-approved hardware. Although FUS is clinically utilized primarily for focal ablation in conditions such as essential tremor, recent breakthroughs have enabled the use of FUS for drug delivery at lower intensities (i.e., tens of watts per square centimeter) without ablation of the tissue. In this review, we present strategies for image-guided FUS-mediated pharmacologic neurointerventions. First, we discuss blood–brain barrier opening to deliver therapeutic agents of a variety of sizes to the central nervous system. We then describe the use of ultrasound-sensitive nanoparticles to noninvasively deliver small molecules to millimeter-sized structures including superficial cortical regions and deep gray matter regions within the brain without the need for blood–brain barrier opening. We also consider the safety and potential complications of these techniques, with attention to temporal acuity. Finally, we close with a discussion of different methods for mapping the ultrasound field within the brain and describe future avenues of research in ultrasound-targeted drug therapies.
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Affiliation(s)
- Jeffrey B Wang
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Tommaso Di Ianni
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Daivik B Vyas
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Zhenbo Huang
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Sunmee Park
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Niloufar Hosseini-Nassab
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Muna Aryal
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
| | - Raag D Airan
- Neuroradiology Division, Department of Radiology, Stanford University, Stanford, CA, United States
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Quah K, Poorman ME, Allen SP, Grissom WA. Simultaneous multislice MRI thermometry with a single coil using incoherent blipped-controlled aliasing. Magn Reson Med 2019; 83:479-491. [PMID: 31402493 DOI: 10.1002/mrm.27940] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/11/2019] [Accepted: 07/17/2019] [Indexed: 12/17/2022]
Abstract
PURPOSE To increase volume coverage in real-time MR thermometry for transcranial MR-guided focused ultrasound (tcMRgFUS) ablation, without multiple receive coils. THEORY AND METHODS Multiband excitation and incoherent blipped-controlled aliasing were implemented in a 2DFT pulse sequence used clinically for tcMRgFUS, and an extended k-space hybrid reconstruction was developed that recovers slice-separated temperature maps assuming that heating is focal, given slice-separated pretreatment images. Simulations were performed to characterize slice leakage, the number of slices that can be simultaneously imaged with low-temperature error, and robustness across random slice-phase k-space permutations. In vivo experiments were performed using a single receive coil without heating to measure temperature precision, and gel phantom FUS experiments were performed to test the method with heating and with a water bath. RESULTS Simulations showed that with large hot spots and identical magnitude images on each slice, up to three slices can be simultaneously imaged with less than 1 ∘ C temperature root-mean-square error. They also showed that hot spots do not alias coherently between slices, and that an average 86% of random slice-phase k-space permutations yielded less than 1 ∘ C temperature error. Temperature precision was not degraded compared to single-slice imaging in the in vivo SMS scans, and the gel phantom SMS temperature maps closely tracked single-slice temperature in the hot spot, with no coherent aliasing to other slices. CONCLUSIONS Incoherent controlled aliasing SMS enables accurate reconstruction of focal heating maps from two or three slices simultaneously, using a single receive coil and a sparsity-promoting temperature reconstruction.
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Affiliation(s)
- Kristin Quah
- Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Megan E Poorman
- Department of Physics, University of Colorado, Boulder, Colorado
| | - Steven P Allen
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - William A Grissom
- Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
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10
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Cao Z, Gore JC, Grissom WA. Low-rank plus sparse compressed sensing for accelerated proton resonance frequency shift MR temperature imaging. Magn Reson Med 2019; 81:3555-3566. [PMID: 30706540 DOI: 10.1002/mrm.27666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/08/2018] [Accepted: 12/31/2018] [Indexed: 12/28/2022]
Abstract
PURPOSE To improve multichannel compressed sensing (CS) reconstruction for MR proton resonance frequency (PRF) shift thermography, with application to MRI-induced RF heating evaluation and MR guided high intensity focused ultrasound (MRgFUS) temperature monitoring. METHODS A new compressed sensing reconstruction is proposed that enforces joint low rank and sparsity of complex difference domain PRF data between post heating and baseline images. Validations were performed on 4 retrospectively undersampled dynamic data sets in PRF applications, by comparing the proposed method to a previously described L1 and total variation- (TV-) based CS approach that also operates on complex difference domain data, and to a conventional low rank plus sparse (L+S) separation-based CS reconstruction applied to the original domain data. RESULTS In all 4 retrospective validations, the proposed reconstruction method outperformed the conventional L+S and L1 +TV CS reconstruction methods with a 3.6× acceleration ratio in terms of temperature accuracy with respect to fully sampled data. For RF heating evaluation, the proposed method achieved RMS error of 12%, compared to 19% for the L+S method and 17% for the L1 +TV method. For in vivo MRgFUS thalamotomy, the peak temperature reconstruction errors were 19%, 31%, and 35%, respectively. CONCLUSION The complex difference-based low rank and sparse model enhances compressibility for dynamic PRF temperature imaging applications. The proposed multichannel CS reconstruction method enables high acceleration factors for PRF applications including RF heating evaluation and MRgFUS sonication.
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Affiliation(s)
- Zhipeng Cao
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Radiology, Vanderbilt University, Nashville, Tennessee
| | - John C Gore
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Radiology, Vanderbilt University, Nashville, Tennessee
| | - William A Grissom
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Radiology, Vanderbilt University, Nashville, Tennessee
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11
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Toccaceli G, Delfini R, Colonnese C, Raco A, Peschillo S. Emerging Strategies and Future Perspective in Neuro-Oncology Using Transcranial Focused Ultrasonography Technology. World Neurosurg 2018; 117:84-91. [DOI: 10.1016/j.wneu.2018.05.239] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/08/2023]
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12
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Fielden SW, Zhao L, Miller GW, Feng X, Geeslin M, Dallapiaza RF, Elias WJ, Wintermark M, Pauly KB, Meyer CH. A spiral-based volumetric acquisition for MR temperature imaging. Magn Reson Med 2018; 79:3122-3127. [PMID: 29115692 PMCID: PMC6377207 DOI: 10.1002/mrm.26981] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 11/09/2022]
Abstract
PURPOSE To develop a rapid pulse sequence for volumetric MR thermometry. METHODS Simulations were carried out to assess temperature deviation, focal spot distortion/blurring, and focal spot shift across a range of readout durations and maximum temperatures for Cartesian, spiral-out, and retraced spiral-in/out (RIO) trajectories. The RIO trajectory was applied for stack-of-spirals 3D imaging on a real-time imaging platform and preliminary evaluation was carried out compared to a standard 2D sequence in vivo using a swine brain model, comparing maximum and mean temperatures measured between the two methods, as well as the temporal standard deviation measured by the two methods. RESULTS In simulations, low-bandwidth Cartesian trajectories showed substantial shift of the focal spot, whereas both spiral trajectories showed no shift while maintaining focal spot geometry. In vivo, the 3D sequence achieved real-time 4D monitoring of thermometry, with an update time of 2.9-3.3 s. CONCLUSION Spiral imaging, and RIO imaging in particular, is an effective way to speed up volumetric MR thermometry. Magn Reson Med 79:3122-3127, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Samuel W. Fielden
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA
| | - Li Zhao
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA
| | - G. Wilson Miller
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA
| | - Xue Feng
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA
| | - Matthew Geeslin
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA
| | | | - W. Jeffrey Elias
- Department of Neurosurgery, University of Virginia, Charlottesville, VA
| | - Max Wintermark
- Department of Radiology, Stanford University, Palo Alto, CA
| | | | - Craig H. Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA
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13
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Crake C, Brinker ST, Coviello CM, Livingstone MS, McDannold NJ. A dual-mode hemispherical sparse array for 3D passive acoustic mapping and skull localization within a clinical MRI guided focused ultrasound device. Phys Med Biol 2018; 63:065008. [PMID: 29459494 DOI: 10.1088/1361-6560/aab0aa] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Previous work has demonstrated that passive acoustic imaging may be used alongside MRI for monitoring of focused ultrasound therapy. However, past implementations have generally made use of either linear arrays originally designed for diagnostic imaging or custom narrowband arrays specific to in-house therapeutic transducer designs, neither of which is fully compatible with clinical MR-guided focused ultrasound (MRgFUS) devices. Here we have designed an array which is suitable for use within an FDA-approved MR-guided transcranial focused ultrasound device, within the bore of a 3 Tesla clinical MRI scanner. The array is constructed from 5 × 0.4 mm piezoceramic disc elements arranged in pseudorandom fashion on a low-profile laser-cut acrylic frame designed to fit between the therapeutic elements of a 230 kHz InSightec ExAblate 4000 transducer. By exploiting thickness and radial resonance modes of the piezo discs the array is capable of both B-mode imaging at 5 MHz for skull localization, as well as passive reception at the second harmonic of the therapy array for detection of cavitation and 3D passive acoustic imaging. In active mode, the array was able to perform B-mode imaging of a human skull, showing the outer skull surface with good qualitative agreement with MR imaging. Extension to 3D showed the array was able to locate the skull within ±2 mm/2° of reference points derived from MRI, which could potentially allow registration of a patient to the therapy system without the expense of real-time MRI. In passive mode, the array was able to resolve a point source in 3D within a ±10 mm region about each axis from the focus, detect cavitation (SNR ~ 12 dB) at burst lengths from 10 cycles to continuous wave, and produce 3D acoustic maps in a flow phantom. Finally, the array was used to detect and map cavitation associated with microbubble activity in the brain in nonhuman primates.
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Affiliation(s)
- Calum Crake
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, United States of America
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14
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15
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Gaur P, Werner B, Feng X, Fielden SW, Meyer CH, Grissom WA. Spatially-segmented undersampled MRI temperature reconstruction for transcranial MR-guided focused ultrasound. J Ther Ultrasound 2017; 5:13. [PMID: 28560040 PMCID: PMC5448150 DOI: 10.1186/s40349-017-0092-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/23/2017] [Indexed: 11/13/2022] Open
Abstract
Background Volumetric thermometry with fine spatiotemporal resolution is desirable to monitor MR-guided focused ultrasound (MRgFUS) procedures in the brain, but requires some form of accelerated imaging. Accelerated MR temperature imaging methods have been developed that undersample k-space and leverage signal correlations over time to suppress the resulting undersampling artifacts. However, in transcranial MRgFUS treatments, the water bath surrounding the skull creates signal variations that do not follow those correlations, leading to temperature errors in the brain due to signal aliasing. Methods To eliminate temperature errors due to the water bath, a spatially-segmented iterative reconstruction method was developed. The method fits a k-space hybrid signal model to reconstruct temperature changes in the brain, and a conventional MR signal model in the water bath. It was evaluated using single-channel 2DFT Cartesian, golden angle radial, and spiral data from gel phantom heating, and in vivo 8-channel 2DFT data from a FUS thalamotomy. Water bath signal intensity in phantom heating images was scaled between 0-100% to investigate its effect on temperature error. Temperature reconstructions of retrospectively undersampled data were performed using the spatially-segmented method, and compared to conventional whole-image k-space hybrid (phantom) and SENSE (in vivo) reconstructions. Results At 100% water bath signal intensity, 3 ×-undersampled spatially-segmented temperature reconstruction error was nearly 5-fold lower than the whole-image k-space hybrid method. Temperature root-mean square error in the hot spot was reduced on average by 27 × (2DFT), 5 × (radial), and 12 × (spiral) using the proposed method. It reduced in vivo error 2 × in the brain for all acceleration factors, and between 2 × and 3 × in the temperature hot spot for 2-4 × undersampling compared to SENSE. Conclusions Separate reconstruction of brain and water bath signals enables accelerated MR temperature imaging during MRgFUS procedures with low errors due to undersampling using Cartesian and non-Cartesian trajectories. The spatially-segmented method benefits from multiple coils, and reconstructs temperature with lower error compared to measurements from SENSE-reconstructed images. The acceleration can be applied to increase volumetric coverage and spatiotemporal resolution.
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Affiliation(s)
- Pooja Gaur
- Department of Radiology, Stanford University, Stanford, USA
| | - Beat Werner
- Center for MR-Research, University Children's Hospital, Zurich, Switzerland
| | - Xue Feng
- Department of Biomedical Engineering, University of Virginia, Charlottesville, USA
| | - Samuel W Fielden
- Autism and Developmental Medicine Institute, Geisinger Health System, Danville, USA
| | - Craig H Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, USA
| | - William A Grissom
- Institute of Imaging Science, Vanderbilt University, 1161 21st Ave S, Nashville, 37232 USA.,Department of Biomedical Engineering, Vanderbilt University, 21st Ave S, Nashville, 37232 USA
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Odéen H, Almquist S, de Bever J, Christensen DA, Parker DL. MR thermometry for focused ultrasound monitoring utilizing model predictive filtering and ultrasound beam modeling. J Ther Ultrasound 2016; 4:23. [PMID: 27688881 PMCID: PMC5032243 DOI: 10.1186/s40349-016-0067-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 09/02/2016] [Indexed: 12/28/2022] Open
Abstract
Background A major challenge in using magnetic resonance temperature imaging (MRTI) to monitor focused ultrasound (FUS) applications is achieving high spatio-temporal resolution over a large field of view (FOV). This is important to accurately monitor all ultrasound (US) power depositions. Magnetic resonance (MR) subsampling in conjunction with thermal model-based reconstruction of the MRTI utilizing Pennes bioheat transfer equation (PBTE) is one promising approach. The thermal properties used in the thermal model are often estimated from a pre-treatment, low-power sonication. Methods In this proof-of-concept study we investigate the use of US simulations computed using the hybrid angular spectrum (HAS) method to estimate the US power deposition density Q, thereby avoiding the pre-treatment sonication and any potential tissue damage. MRTI reconstructions are performed using a thermal model-based reconstruction method called model predictive filtering (MPF). Experiments are performed in a homogeneous gelatin phantom and in a gelatin phantom with embedded plastic skull. MPF reconstructions are compared to separate sonications imaged with fully sampled data over a smaller FOV. Temperature root-mean-square errors (RMSE) and focal spot positions and shapes are evaluated. Results HAS simulations accurately predict the location of the focal spot (to within 1 mm) in both phantoms. Accurate temperature maps (RMSE below 1 °C), where the location of the focal spot agrees well with fully sampled “truth” (to within 1 mm), are also achieved in both phantoms. Conclusions HAS simulations can be used to accurately predict the focal spot location in homogeneous media and when focusing through an aberrating plastic skull. The HAS simulated power deposition (Q) patterns can be used in the MPF thermal model-based reconstruction to obtain accurate temperature maps with high spatio-temporal resolution over large FOVs.
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Affiliation(s)
- Henrik Odéen
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA
| | - Scott Almquist
- School of Computing, University of Utah, Salt Lake City, UT USA
| | - Joshua de Bever
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA
| | - Douglas A Christensen
- Department of Bioengineering, University of Utah, Salt Lake City, UT USA ; Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT USA
| | - Dennis L Parker
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA
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Farrer AI, Odéen H, de Bever J, Coats B, Parker DL, Payne A, Christensen DA. Characterization and evaluation of tissue-mimicking gelatin phantoms for use with MRgFUS. J Ther Ultrasound 2015; 3:9. [PMID: 26146557 PMCID: PMC4490606 DOI: 10.1186/s40349-015-0030-y] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/29/2015] [Indexed: 01/12/2023] Open
Abstract
Background A tissue-mimicking phantom that accurately represents human-tissue properties is important for safety testing and for validating new imaging techniques. To achieve a variety of desired human-tissue properties, we have fabricated and tested several variations of gelatin phantoms. These phantoms are simple to manufacture and have properties in the same order of magnitude as those of soft tissues. This is important for quality-assurance verification as well as validation of magnetic resonance-guided focused ultrasound (MRgFUS) treatment techniques. Methods The phantoms presented in this work were constructed from gelatin powders with three different bloom values (125, 175, and 250), each one allowing for a different mechanical stiffness of the phantom. Evaporated milk was used to replace half of the water in the recipe for the gelatin phantoms in order to achieve attenuation and speed of sound values in soft tissue ranges. These acoustic properties, along with MR (T1 and T2*), mechanical (density and Young’s modulus), and thermal properties (thermal diffusivity and specific heat capacity), were obtained through independent measurements for all three bloom types to characterize the gelatin phantoms. Thermal repeatability of the phantoms was also assessed using MRgFUS and MR thermometry. Results All the measured values fell within the literature-reported ranges of soft tissues. In heating tests using low-power (6.6 W) sonications, interleaved with high-power (up to 22.0 W) sonications, each of the three different bloom phantoms demonstrated repeatable temperature increases (10.4 ± 0.3 °C for 125-bloom, 10.2 ± 0.3 °C for 175-bloom, and 10.8 ± 0.2 °C for 250-bloom for all 6.6-W sonications) for heating durations of 18.1 s. Conclusion These evaporated milk-modified gelatin phantoms should serve as reliable, general soft tissue-mimicking MRgFUS phantoms.
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Affiliation(s)
- Alexis I Farrer
- Department of Bioengineering, University of Utah, Salt Lake City, UT USA ; Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA
| | - Henrik Odéen
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA ; Department of Physics and Astronomy, University of Utah, Salt Lake City, UT USA
| | - Joshua de Bever
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA ; School of Computing, University of Utah, Salt Lake City, UT USA
| | - Brittany Coats
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT USA
| | - Dennis L Parker
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA
| | - Allison Payne
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT USA
| | - Douglas A Christensen
- Department of Bioengineering, University of Utah, Salt Lake City, UT USA ; Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT USA
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Odéen H, Todd N, Dillon C, Payne A, Parker DL. Model predictive filtering MR thermometry: Effects of model inaccuracies, k-space reduction factor, and temperature increase rate. Magn Reson Med 2015; 75:207-16. [PMID: 25726934 DOI: 10.1002/mrm.25622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 12/24/2014] [Accepted: 12/29/2014] [Indexed: 01/20/2023]
Abstract
PURPOSE Evaluate effects of model parameter inaccuracies (thermal conductivity, k, and ultrasound power deposition density, Q), k-space reduction factor (R), and rate of temperature increase ( T˙) in a thermal model-based reconstruction for MR-thermometry during focused-ultrasound heating. METHODS Simulations and ex vivo experiments were performed to investigate the accuracy of the thermal model and the model predictive filtering (MPF) algorithm for varying R and T˙, and their sensitivity to errors in k and Q. Ex vivo data was acquired with a segmented EPI pulse sequence to achieve large field-of-view (192 × 162 × 96 mm) four-dimensional temperature maps with high spatiotemporal resolution (1.5 × 1.5 × 2.0 mm, 1.7 s). RESULTS In the simulations, 50% errors in k and Q resulted in maximum temperature root mean square errors (RMSE) of 6 °C for model only and 3 °C for MPF. Using recently developed methods, estimates of k and Q were accurate to within 3%. The RMSE between MPF and true temperature increased with R and T˙. In the ex vivo study the RMSE remained below 0.7 °C for R ranging from 4 to 12 and T˙ of 0.28-0.75 °C/s. CONCLUSION Errors in MPF temperatures occur due to errors in k and Q. These MPF temperature errors increase with increase in R and T˙, but are smaller than those obtained using the thermal model alone.
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Affiliation(s)
- Henrik Odéen
- Department of Radiology, University of Utah, Salt Lake City, Utah, USA.,Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, USA
| | - Nick Todd
- Department of Radiology, University of Utah, Salt Lake City, Utah, USA
| | - Christopher Dillon
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
| | - Allison Payne
- Department of Radiology, University of Utah, Salt Lake City, Utah, USA
| | - Dennis L Parker
- Department of Radiology, University of Utah, Salt Lake City, Utah, USA
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