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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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Jiang Z, Cudeiro-Blanco J, Ilbilgi Yildiz B, Sujarittam K, Dickinson RJ, Guasch L, Tang M, Hall TL, Choi JJ. An Ultrasound Array of Emitter-Receiver Stacks for Microbubble-Based Therapy. IEEE Trans Biomed Eng 2024; 71:467-476. [PMID: 37607156 DOI: 10.1109/tbme.2023.3307462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Most therapeutic ultrasound devices place emitters and receivers in separate locations, so that the long therapeutic pulses (>1 ms) can be emitted while receivers monitor the procedure. However, with such placement, emitters and receivers are competing for the same space, producing a trade-off between emission efficiency and reception sensitivity. Taking advantage of recent studies demonstrating that short-pulse ultrasound can be used therapeutically, we aimed to develop a device that overcomes such trade-offs. The array was composed of emitter-receiver stacks, which enabled both emission and reception from the same location. Each element was made of a lead zirconate titanate (PZT)-polyvinylidene fluoride (PVDF) stack. The PZT (frequency: 500 kHz, diameter: 16 mm) was used for emission and the PVDF (thickness: 28 μm, diameter: 16 mm) for broadband reception. 32 elements were assembled in a 3D-printed dome-shaped frame (focal length: 150 mm; [Formula: see text]-number: 1) and was tested in free-field and through an ex-vivo human skull. In free-field, the array had a 4.5 × 4.5 × 32 mm focus and produced a peak-negative pressure (PNP) of 2.12 MPa at its geometric center. The electronic steering range was ±15 mm laterally and larger than ±15 mm axially. Through the skull, the array produced a PNP of 0.63 MPa. The PVDF elements were able to localize broadband microbubble emissions across the skull. We built the first multi-element array for short-pulse and microbubble-based therapeutic applications. Stacked arrays overcome traditional trade-offs between the transmission and reception quality and have the potential to create a step change in treatment safety and efficacy.
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Huang L, Qiao S, Ling W, Wang W, Feng Q, Cao J, Luo Y. Technical note: High-efficient and wireless transcranial ultrasound excitation based on electromagnetic acoustic transducer. Med Phys 2024; 51:662-669. [PMID: 37815210 DOI: 10.1002/mp.16732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 10/11/2023] Open
Abstract
BACKGROUND The generation of transcranial ultrasound is usually based on the piezoelectric effect, so it is necessary to attach transducers around the skull. However, the skull will cause serious attenuation and scattering of ultrasound, which makes it particularly difficult for transcranial ultrasound imaging and modulation. PURPOSE In transcranial ultrasound imaging, there is significant attenuation and scattering of ultrasound waves by the skull bone. To mitigate this influence and enable precise imaging and high-efficient transcranial ultrasound for specific patients (such as stroke patients who already require craniotomy as part of their surgical care), this paper proposes to use EMAT to excite metal plates placed inside the skull based on the excellent penetration characteristics of EM waves into the skull, generating ultrasound signals, which can completely avoid the influence of skull on ultrasound transmission. METHODS Based on an efficient wireless transcranial ultrasound experimental platform, we first verified that the skull would not affect the propagation of electromagnetic waves generated by EMAT. In addition, the distribution of the transcranial sound field generated by EMAT was measured. RESULTS EMAT can generate 1.0 MHz ultrasound by wireless excitation of a 0.1 mm thick copper plate through an adult skull with a thickness of ∼1 cm, and the frequency and amplitude of the generated ultrasound are not affected by the skull. The results indicated that the electromagnetic waves successfully penetrated the skull, with a recorded strength of approximately 2 mV. We also found that the ultrasound signals generated by the EMAT probe through the skull remained unaffected, measuring around 2 mV. In addition, the measurement of the transcranial sound field distribution (80*50 mm2 ) generated by EMAT shows that compared with the traditional extracranial ultrasound generation method, the sound field distribution generated by the wireless excitation of the intracranial copper plate based on EAMT is no longer affected by the uneven and irregular skull. CONCLUSION Our experiments involved validating the penetration capabilities of electromagnetic waves utilizing the EMAT probe through a 7 (5+2) mm thick organic glass plate and a real human skull ranging from 8 to 15 mm in thickness. The efficient and wireless transcranial ultrasound excitation proposed in this paper may be possible for transcranial ultrasound imaging and therapy.
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Affiliation(s)
- Lin Huang
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, China
- Zhangjiang Laboratory, Shanghai, China
| | - Shuaiqi Qiao
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, China
- Zhangjiang Laboratory, Shanghai, China
| | - Wenwu Ling
- West China Hospital, Sichuan University, Chengdu, China
| | - Weipeng Wang
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, China
- Zhangjiang Laboratory, Shanghai, China
| | - Qikaiyi Feng
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, China
- Zhangjiang Laboratory, Shanghai, China
| | - Jiazhi Cao
- West China Hospital, Sichuan University, Chengdu, China
| | - Yan Luo
- West China Hospital, Sichuan University, Chengdu, China
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Zhang D, Wang X, Lin J, Xiong Y, Lu H, Huang J, Lou X. Multi-frequency therapeutic ultrasound: A review. ULTRASONICS SONOCHEMISTRY 2023; 100:106608. [PMID: 37774469 PMCID: PMC10543167 DOI: 10.1016/j.ultsonch.2023.106608] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 09/08/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023]
Abstract
Focused ultrasound is a noninvasive, radiation-free and real-time therapeutic approach to treat deep-seated targets, which benefits numerous diseases otherwise requiring surgeries. Treatment efficiency is one of the key factors determining therapeutic outcomes, but improving it solely by increasing the total power can be limited by the performance of general ultrasound devices. To address this, multi-frequency therapeutic ultrasound, using additional ultrasound waves of different frequencies on top of the standard single-frequency wave, provides a promising method for treatment efficiency enhancement with limited power. Several applications and numerical works have demonstrated its superiority on treatment enhancement. This paper presents an overview of the mechanisms, implementations, applications and decisive parameters of the multi-frequency therapeutic ultrasound, which could help to pave the way for better understanding and further developing this technology in the future.
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Affiliation(s)
- Dong Zhang
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Xiaoyu Wang
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Jiaji Lin
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Yongqin Xiong
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Haoxuan Lu
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Jiayu Huang
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Xin Lou
- Department of Radiology, Chinese PLA General Hospital, Beijing, China.
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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: 0] [Impact Index Per Article: 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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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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Remus: System for remote deep brain interventions. iScience 2022; 25:105251. [PMID: 36304108 PMCID: PMC9593303 DOI: 10.1016/j.isci.2022.105251] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 05/17/2022] [Accepted: 09/27/2022] [Indexed: 11/22/2022] Open
Abstract
Transcranial-focused ultrasound brings personalized medicine to the human brain. Ultrasound can modulate neural activity or release drugs in specific neural circuits but this personalized approach requires a system that delivers ultrasound into specified targets flexibly and on command. We developed a remote ultrasound system (Remus) that programmatically targets deep brain regions with high spatiotemporal precision and in a multi-focal manner. We validated these functions by modulating two deep brain nuclei—the left and right lateral geniculate nucleus—in a task-performing nonhuman primate. This flexible system will enable researchers and clinicians to diagnose and treat specific deep brain circuits in a noninvasive yet targeted manner, thus embodying the promise of personalized treatments of brain disorders. Remus delivers ultrasound into deep brain targets of task-performing subjects Targets are specified programmatically and at high spatial and temporal precision Brief pulses delivered to deep brain regions modulate visual choice behavior The system enables reproducible daily applications and continuous safety monitoring
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Hu Z, Chen S, Yang Y, Gong Y, Chen H. An Affordable and Easy-to-Use Focused Ultrasound Device for Noninvasive and High Precision Drug Delivery to the Mouse Brain. IEEE Trans Biomed Eng 2022; 69:2723-2732. [PMID: 35157574 PMCID: PMC9443669 DOI: 10.1109/tbme.2022.3150781] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Focused ultrasound (FUS) combined with microbubble-mediated blood-brain barrier (BBB) opening (FUS-BBBO) is not only a promising technique for clinical applications but also a powerful tool for preclinical research. However, existing FUS devices for preclinical research are expensive, bulky, and lack the precision needed for small animal research, which limits the broad adoption of this promising technique by the research community. Our objective was to design and fabricate an affordable, easy-to-use, high-precision FUS device for small animal research. METHODS We designed and fabricated in-house mini-FUS transducers (∼$80 each in material cost) with three frequencies (1.5, 3.0, and 6.0 MHz) and integrated them with a stereotactic frame for precise mouse brain targeting using established stereotactic procedures. The BBB opening volume by FUS at different acoustic pressures (0.20-0.57 MPa) was quantified using T1-weighted contrast-enhanced magnetic resonance imaging of gadolinium leakage and fluorescence imaging of Evans blue extravasation. RESULTS The targeting accuracy of the device as measured by the offset between the desired target location and the centroid of BBBO was 0.63 ± 0.19 mm. The spatial precision of the device in targeting individual brain structures was improved by the use of higher frequency FUS transducers. The BBB opening volume had high linear correlations with the cavitation index (defined by the ratio between acoustic pressure and frequency) and mechanical index (defined by the ratio between acoustic pressure and the square root of frequency). The correlation coefficient of the cavitation index was slightly higher than that of the mechanical index. CONCLUSION This study demonstrated that spatially accurate and precise BBB opening was achievable using an affordable and easy-to-use FUS device. The BBB opening volume was tunable by modulating the cavitation index. This device is expected to decrease the barriers to the adoption of the FUS-BBBO technique by the broad research community.
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Hoang TN, Lin HC, Tsai CH, Jan CK, Liu HL. Passive Cavitation Enhancement Mapping via an Ultrasound Dual-Mode phased array to monitor blood-brain barrier opening. J Med Biol Eng 2022. [DOI: 10.1007/s40846-022-00735-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Schoen S, Kilinc MS, Lee H, Guo Y, Degertekin FL, Woodworth GF, Arvanitis C. Towards controlled drug delivery in brain tumors with microbubble-enhanced focused ultrasound. Adv Drug Deliv Rev 2022; 180:114043. [PMID: 34801617 PMCID: PMC8724442 DOI: 10.1016/j.addr.2021.114043] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 09/27/2021] [Accepted: 11/04/2021] [Indexed: 02/06/2023]
Abstract
Brain tumors are particularly challenging malignancies, due to their location in a structurally and functionally distinct part of the human body - the central nervous system (CNS). The CNS is separated and protected by a unique system of brain and blood vessel cells which together prevent most bloodborne therapeutics from entering the brain tumor microenvironment (TME). Recently, great strides have been made through microbubble (MB) ultrasound contrast agents in conjunction with ultrasound energy to locally increase the permeability of brain vessels and modulate the brain TME. As we elaborate in this review, this physical method can effectively deliver a wide range of anticancer agents, including chemotherapeutics, antibodies, and nanoparticle drug conjugates across a range of preclinical brain tumors, including high grade glioma (glioblastoma), diffuse intrinsic pontine gliomas, and brain metastasis. Moreover, recent evidence suggests that this technology can promote the effective delivery of novel immunotherapeutic agents, including immune check-point inhibitors and chimeric antigen receptor T cells, among others. With early clinical studies demonstrating safety, and several Phase I/II trials testing the preclinical findings underway, this technology is making firm steps towards shaping the future treatments of primary and metastatic brain cancer. By elaborating on its key components, including ultrasound systems and MB technology, along with methods for closed-loop spatial and temporal control of MB activity, we highlight how this technology can be tuned to enable new, personalized treatment strategies for primary brain malignancies and brain metastases.
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Affiliation(s)
- Scott Schoen
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - M. Sait Kilinc
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Hohyun Lee
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Yutong Guo
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - F. Levent Degertekin
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Graeme F. Woodworth
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA,Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, College Park, MD 20742, USA,Fischell Department of Bioengineering A. James Clarke School of Engineering, University of Maryland
| | - Costas Arvanitis
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA,Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
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Batts A, Ji R, Kline-Schoder A, Noel R, Konofagou E. Transcranial Theranostic Ultrasound for Pre-Planning and Blood-Brain Barrier Opening: A Feasibility Study Using an Imaging Phased Array In Vitro and In Vivo. IEEE Trans Biomed Eng 2021; 69:1481-1490. [PMID: 34665716 DOI: 10.1109/tbme.2021.3120919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Focused ultrasound (FUS) for blood-brain barrier (BBB) opening is a safe, reversible and non-invasive strategy for targeted drug delivery to the brain, however extensive pre-planning strategies are necessary for successful FUS-mediated BBB opening through the structurally complex primate skull. OBJECTIVE This work aims to demonstrate a pre-planning pipeline consisting of transcranial simulations and in vitro experimentation used to inform synchronous BBB opening and power cavitation imaging (PCI) with a single theranostic ultrasound (TUS) phased array. METHODS Acoustic wave propagation simulation readouts of pressure attenuation and focal shift through clinical-CT and micro-CT-based primate skull models were compared, while the latter were used to determine the impact of beam steering angle on focal shift and pressure attenuation. In vitro experimentation with a channel phantom enabled characterization of skull-induced receive focal shift (RFS), while in vivo BBB opening and PCI using in silico and in vitro pre-planning information was conducted using a custom Verasonics/MATLAB script. RESULTS Simulations confirmed steering angle dependent transcranial focal shift and pressure attenuation, while in vitro experiments revealed minimal (0.30-1.50 mm) skull-induced RFS. In vivo rodent experiments with overlaid primate skull fragments demonstrated successful TUS-mediated BBB opening and spatially correlated power cavitation images (PCI) with regions of BBB opening on T1-weighted magnetic resonance images (MRI). CONCLUSION Herein, we demonstrate the feasibility for TUS-mediated BBB opening in vivo using in silico and in vitro pre-planning information. SIGNIFICANCE TUS as an ultrasound-guided modality for BBB opening could be a promising alternative to current FUS-mediated BBB opening configurations in the clinic.
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Qiu W, Bouakaz A, Konofagou EE, Zheng H. Ultrasound for the Brain: A Review of Physical and Engineering Principles, and Clinical Applications. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:6-20. [PMID: 32866096 DOI: 10.1109/tuffc.2020.3019932] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The emergence of new ultrasound technologies has improved our understanding of the brain functions and offered new opportunities for the treatment of brain diseases. Ultrasound has become a valuable tool in preclinical animal and clinical studies as it not only provides information about the structure and function of brain tissues but can also be used as a therapy alternative for brain diseases. High-resolution cerebral flow images with high sensitivity can be acquired using novel functional ultrasound and super-resolution ultrasound imaging techniques. The noninvasive treatment of essential tremors has been clinically approved and it has been demonstrated that the ultrasound technology can revolutionize the currently existing treatment methods. Microbubble-mediated ultrasound can remotely open the blood-brain barrier enabling targeted drug delivery in the brain. More recently, ultrasound neuromodulation received a great amount of attention due to its noninvasive and deep penetration features and potential therapeutic benefits. This review provides a thorough introduction to the current state-of-the-art research on brain ultrasound and also introduces basic knowledge of brain ultrasound including the acoustic properties of the brain/skull and engineering techniques for ultrasound. Ultrasound is expected to play an increasingly important role in the diagnosis and therapy of brain diseases.
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Zhou J, Li J, Zhong H, Shi X, Yang G, Huang J, Li Y, Ma T, Long X, Qiu W, Zheng H. Fiber-Based Clock Synchronization Method for Medical Ultrasound System. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:136-142. [PMID: 32406832 DOI: 10.1109/tuffc.2020.2994097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Brain ultrasound has attracted great attention recently due to its noninvasive treatment function for brain diseases. However, ultrasound is still difficult to pass through an intact skull. Phase correction is recognized as an effective method for skull compensation. Half-wavelength pitch transducer is important for the phase correction and, hence, thousands of elements array is required to cover large area human tissue. The clock synchronization between elements is crucial for the phase correction; however, the traditional clock scheme which is designed for 128- or 256-element system is not suitable for thousands of elements. In addition, the clock scheme needs to be magnetic resonance imaging (MRI) compatible since MRI-guided intervention is becoming a routine operation for the brain ultrasound. This study is the first to propose an optical fiber-based clock synchronization method for MRI-guided ultrasound array system. The optical fiber not only distributes the clock but also sets up a link to transmit the data for ultrasound beamformer. The link is full-duplex so both the clock and the data can be transmitted and received simultaneously. The precision of clock synchronization is less than 557 ps when using 50 MHz clock, and the period jitter of the clock is less than 10 ps (rms). Multiple 128- or 256-channel ultrasonic systems can be synchronized, and the error between the channels can be less than 10 ns when using 1-MHz ultrasound transducer. The system can work in an MRI scanning room and communicate with a console via only one fiber. In vivo primate animal study has been achieved, and it has been proven that the proposed clock scheme is suitable for MRI-guided large-scale ultrasound array system.
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14
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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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15
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Kung Y, Huang HY, Liao WH, Huang APH, Hsiao MY, Wu CH, Liu HL, Inserra C, Chen WS. A Single High-Intensity Shock Wave Pulse With Microbubbles Opens the Blood-Brain Barrier in Rats. Front Bioeng Biotechnol 2020; 8:402. [PMID: 32478046 PMCID: PMC7232561 DOI: 10.3389/fbioe.2020.00402] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/09/2020] [Indexed: 12/22/2022] Open
Abstract
Focused extracorporeal shockwave (FSW), one kind of focused high-intensity pulsed ultrasound, has been shown to induce blood-brain barrier (BBB) opening in targeted brain areas in rat animal models with minimal detrimental effects below threshold intensity levels or iterations. In the current study, we found that the thresholds could be further reduced by the addition of microbubbles (ultrasound contrast agents or UCA; SonoVue). FSW with 2 × 106 MBs/kg of UCA (20% of clinical dosage) at an intensity level of 0.1 (peak positive pressure 5.4 MPa; peak negative pressure -4.2 MPa; energy flux density 0.03 mJ/mm2) resulting in a 100% BBB opening rate without detectable hemorrhage or apoptosis in the brain. Significantly reduced free radical production was found compared with 0.5 MHz focused ultrasound at a peak negative pressure of 0.44 MPa (1% duty cycle and 4 × 107 MBs/kg of UCA). FSW devices offer advantages of commercial availability and high safety, and thus may facilitate future research and applications of focal BBB opening for oncological and pharmacological purposes.
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Affiliation(s)
- Yi Kung
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hsin-Yu Huang
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Wei-Hao Liao
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Abel P.-H. Huang
- Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | - Ming-Yen Hsiao
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Chueh-Hung Wu
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hao-Li Liu
- Department of Electrical Engineering, Chang Gung University, Taoyuan, Taiwan
| | - Claude Inserra
- INSERM, U1032, LabTAU, Universiteì Claude Bernard Lyon 1, Lyon, France
| | - Wen-Shiang Chen
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
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16
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Brinker ST, Preiswerk F, White PJ, Mariano TY, McDannold NJ, Bubrick EJ. Focused Ultrasound Platform for Investigating Therapeutic Neuromodulation Across the Human Hippocampus. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:1270-1274. [PMID: 32088061 PMCID: PMC7239323 DOI: 10.1016/j.ultrasmedbio.2020.01.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/03/2020] [Accepted: 01/13/2020] [Indexed: 05/25/2023]
Abstract
Pulsed low-intensity focused ultrasound (PLIFUS) has shown promise in inducing neuromodulation in several animal and human studies. Therefore, it is of clinical interest to develop experimental platforms to test repetitive PLIFUS as a therapeutic modality in humans with neurologic disorders. In the study described here, our aim was to develop a laboratory-built experimental device platform intended to deliver repetitive PLIFUS across the hippocampus in seizure onset zones of patients with drug-resistant temporal lobe epilepsy. The system uses neuronavigation targeting over multiple therapeutic sessions. PLIFUS (548 kHz) was emitted across multiple hippocampal targets in a human subject with temporal lobe epilepsy using a mechanically steered piezoelectric transducer. Stimulation was delivered up to 2.25 W/cm2 spatial peak temporal average intensity (free-field equivalent), with 36%-50% duty cycle, 500-ms sonications and 7-s inter-stimulation intervals lasting 140 s per target and repeated for multiple sessions. A first-in-human PLIFUS course of treatment was successfully delivered using the device platform with no adverse events.
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Affiliation(s)
- Spencer T Brinker
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Frank Preiswerk
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Phillip J White
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Physics, Simmons College, Boston, Massachusetts, USA
| | - Timothy Y Mariano
- Center for Neurorestoration and Neurotechnology, Providence Veterans Affairs Medical Center, Providence, Rhode Island, USA; Butler Hospital, Providence, Rhode Island, USA; Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Nathan J McDannold
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
| | - Ellen J Bubrick
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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17
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Jiang C, Li D, Xu F, Li Y, Liu C, Ta D. Numerical Evaluation of the Influence of Skull Heterogeneity on Transcranial Ultrasonic Focusing. Front Neurosci 2020; 14:317. [PMID: 32351351 PMCID: PMC7174677 DOI: 10.3389/fnins.2020.00317] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 03/17/2020] [Indexed: 11/13/2022] Open
Abstract
In transcranial penetration, ultrasound undergoes refraction, diffraction, multi-reflection, and mode conversion. These factors lead to phase aberration and waveform distortion, which impede the realization of transcranial ultrasonic imaging and therapy. Ray tracing has been used to correct the phase aberration and is computationally more efficient than traditional full-wave simulation. However, when ray tracing has been used for transcranial investigation, it has generally been on the premise that the skull medium is homogeneous. To find suitable homogeneity that balances computational speed and accuracy, the present work investigates how the focus deviates after phase-aberration compensation with ray tracing using time-reversal theory. The waveforms are synthetized with ray tracing for phase aberration, by which the properties of the skull bone are simplified for refraction calculation as those of either (i) the cortical bone or (ii) the mean of the entire skull bone, and the focusing accuracy is evaluated for each hypothesis. The propagation of ultrasound for transcranial focusing is simulated with the elastic model using the k-space pseudospectral method. Unlike the fluid model, the elastic model does not omit shear waves in the skull bones, and the influence of that omission is investigated, with the fluid model resulting in a focal deflection of 0.5 mm. The focusing deviations are huge when the properties of the skull bone are idealized with ray tracing as those of the mean of the entire skull bone. The focusing accuracy improves when the properties of the skull bone are idealized as those of the cortical bone. The results reveal minimal deviation (8.6, 3.9, and 3.2% in the three Cartesian coordinates) in the focal region and suggest that transcranial focusing deflections are caused mostly by ultrasonic refraction on the surface of the skull bone. A heterogeneous skull bone causes wave bending but minimal focusing deflection. The proposed simplification of a homogeneous skull bone is more accurate for transcranial ultrasonic path estimation and offers promising applications in transcranial ultrasonic focusing and imaging.
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Affiliation(s)
- Chen Jiang
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Dan Li
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Feng Xu
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Ying Li
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Chengcheng Liu
- Institute of Acoustics, Tongji University, Shanghai, China
| | - Dean Ta
- Department of Electronic Engineering, Fudan University, Shanghai, China.,State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, China.,Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, Shanghai, China
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18
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Ilyas A, Chen CJ, Ding D, Romeo A, Buell TJ, Wang TR, Kalani MYS, Park MS. Magnetic resonance-guided, high-intensity focused ultrasound sonolysis: potential applications for stroke. Neurosurg Focus 2019; 44:E12. [PMID: 29385918 DOI: 10.3171/2017.11.focus17608] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Stroke is one of the leading causes of death worldwide and a significant source of long-term morbidity. Unfortunately, a substantial number of stroke patients either are ineligible or do not significantly benefit from contemporary medical and interventional therapies. To address this void, investigators recently made technological advances to render transcranial MR-guided, high-intensity focused ultrasound (MRg-HIFU) sonolysis a potential therapeutic option for both acute ischemic stroke (AIS)-as an alternative for patients with emergent large-vessel occlusion (ELVO) who are ineligible for endovascular mechanical thrombectomy (EMT) or as salvage therapy for patients in whom EMT fails-and intracerebral hemorrhage (ICH)-as a neoadjuvant means of clot lysis prior to surgical evacuation. Herein, the authors review the technological principles behind MRg-HIFU sonolysis, its results in in vitro and in vivo stroke models, and its potential clinical applications. As a noninvasive transcranial technique that affords rapid clot lysis, MRg-HIFU thrombolysis may develop into a therapeutic option for patients with AIS or ICH. However, additional studies of transcranial MRg-HIFU are necessary to ascertain the merit of this treatment approach for thrombolysis in both AIS and ICH, as well as its technical limitations and risks.
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Affiliation(s)
- Adeel Ilyas
- Department of Neurosurgery, University of Alabama at Birmingham, Alabama
| | - Ching-Jen Chen
- Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and
| | - Dale Ding
- Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona
| | - Andrew Romeo
- Department of Neurosurgery, University of Alabama at Birmingham, Alabama
| | - Thomas J Buell
- Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and
| | - Tony R Wang
- Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and
| | - M Yashar S Kalani
- Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and
| | - Min S Park
- Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and
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19
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Liu HL, Tsai CH, Jan CK, Chang HY, Huang SM, Li ML, Qiu W, Zheng H. Design and Implementation of a Transmit/Receive Ultrasound Phased Array for Brain Applications. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2018; 65:1756-1767. [PMID: 30010555 DOI: 10.1109/tuffc.2018.2855181] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Focused ultrasound phased array systems have attracted increased attention for brain therapy applications. However, such systems currently lack a direct and real-time method to intraoperatively monitor ultrasound pressure distribution for securing treatment. This study proposes a dual-mode ultrasound phased array system design to support transmit/receive operations for concurrent ultrasound exposure and backscattered focal beam reconstruction through a spherically focused ultrasound array. A 256-channel ultrasound transmission system was used to transmit focused ultrasonic energy (full 256 channels), with an extended implementation of multiple-channel receiving function (up to 64 channels) using the same 256-channel ultrasound array. A coherent backscatter-received beam formation algorithm was implemented to map the point spread function (PSF) and focal beam distribution under a free-field/transcranial environment setup, with the backscattering generated from a strong scatterer (a point reflector or a microbubble-perfused tube) or a weakly scattered tissue-mimicking graphite phantom. Our results showed that PSF and focal beam can be successfully reconstructed and visualized in free-field conditions and can also be transcranially reconstructed following skull-induced aberration correction. In vivo experiments were conducted to demonstrate its capability to preoperatively and semiquantitatively map a focal beam to guide blood-brain barrier opening. The proposed system may have potential for real-time guidance of ultrasound brain intervention, and may facilitate the design of a dual-mode ultrasound phased array for brain therapeutic applications.
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20
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Pelekanos M, Leinenga G, Odabaee M, Odabaee M, Saifzadeh S, Steck R, Götz J. Establishing sheep as an experimental species to validate ultrasound-mediated blood-brain barrier opening for potential therapeutic interventions. Am J Cancer Res 2018; 8:2583-2602. [PMID: 29721100 PMCID: PMC5928910 DOI: 10.7150/thno.22852] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/02/2018] [Indexed: 11/14/2022] Open
Abstract
Rationale: Treating diseases of the brain such as Alzheimer's disease (AD) is challenging as the blood-brain barrier (BBB) effectively restricts access of a large number of potentially useful drugs. A potential solution to this problem is presented by therapeutic ultrasound, a novel treatment modality that can achieve transient BBB opening in species including rodents, facilitated by biologically inert microbubbles that are routinely used in a clinical setting for contrast enhancement. However, in translating rodent studies to the human brain, the presence of a thick cancellous skull that both absorbs and distorts ultrasound presents a challenge. A larger animal model that is more similar to humans is therefore required in order to establish a suitable protocol and to test devices. Here we investigated whether sheep provide such a model. Methods: In a stepwise manner, we used a total of 12 sheep to establish a sonication protocol using a spherically focused transducer. This was assisted by ex vivo simulations based on CT scans to establish suitable sonication parameters. BBB opening was assessed by Evans blue staining and a range of histological tests. Results: Here we demonstrate noninvasive microbubble-mediated BBB opening through the intact sheep skull. Our non-recovery protocol allowed for BBB opening at the base of the brain, and in areas relevant for AD, including the cortex and hippocampus. Linear time-shift invariant analysis and finite element analysis simulations were used to optimize the position of the transducer and to predict the acoustic pressure and location of the focus. Conclusion: Our study establishes sheep as a novel animal model for ultrasound-mediated BBB opening and highlights opportunities and challenges in using this model. Moreover, as sheep develop an AD-like pathology with aging, they represent a large animal model that could potentially complement the use of non-human primates.
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21
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Image-Guided Focused-Ultrasound CNS Molecular Delivery: An Implementation via Dynamic Contrast-Enhanced Magnetic-Resonance Imaging. Sci Rep 2018. [PMID: 29515222 PMCID: PMC5841286 DOI: 10.1038/s41598-018-22571-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Focused ultrasound (FUS) exposure with microbubbles can transiently open the blood-brain barrier (BBB) to deliver therapeutic molecules into CNS tissues. However, delivered molecular distribution/concentration at the target need to be controlled. Dynamic Contrast-Enhanced Magnetic-Resonance Imaging (DCE-MRI) is a well-established protocol for monitoring the pharmacokinetic/pharmacodynamic behavior of FUS-BBB opening. This study investigates the feasibility of using DCE-MRI to estimate molecular CNS penetration under various exposure conditions and molecule sizes. In the 1st stage, a relationship among the imaging index Ktrans, exposure level and molecular size was calibrated and established. In the 2nd stage, various exposure levels and distinct molecules were applied to evaluate the estimated molecular concentration discrepancy with the quantified ones. High correlation (r2 = 0.9684) between Ktrans and transcranial mechanical index (MI) implies Ktrans can serve as an in vivo imaging index to mirror FUS-BBB opening scale. When testing various molecules with the size ranging 1–149 kDa, an overall correlation of r2 = 0.9915 between quantified and predicted concentrations was reached, suggesting the established model can provide reasonably accurate estimation. Our work demonstrates the feasibility of estimating molecular penetration through FUS-BBB opening via DCE-MRI and may facilitate development of FUS-induced BBB opening in brain drug delivery.
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22
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Lamsam L, Johnson E, Connolly ID, Wintermark M, Hayden Gephart M. A review of potential applications of MR-guided focused ultrasound for targeting brain tumor therapy. Neurosurg Focus 2018; 44:E10. [DOI: 10.3171/2017.11.focus17620] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Magnetic resonance–guided focused ultrasound (MRgFUS) has been used extensively to ablate brain tissue in movement disorders, such as essential tremor. At a lower energy, MRgFUS can disrupt the blood-brain barrier (BBB) to allow passage of drugs. This focal disruption of the BBB can target systemic medications to specific portions of the brain, such as for brain tumors. Current methods to bypass the BBB are invasive, as the BBB is relatively impermeable to systemically delivered antineoplastic agents. Multiple healthy and brain tumor animal models have suggested that MRgFUS disrupts the BBB and focally increases the concentration of systemically delivered antitumor chemotherapy, immunotherapy, and gene therapy. In animal tumor models, combining MRgFUS with systemic drug delivery increases median survival times and delays tumor progression. Liposomes, modified microbubbles, and magnetic nanoparticles, combined with MRgFUS, more effectively deliver chemotherapy to brain tumors. MRgFUS has great potential to enhance brain tumor drug delivery, while limiting treatment toxicity to the healthy brain.
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Affiliation(s)
| | | | | | - Max Wintermark
- 2Radiology, Stanford University Medical Center, Stanford, California
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23
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Hughes A, Hynynen K. Design of patient-specific focused ultrasound arrays for non-invasive brain therapy with increased trans-skull transmission and steering range. Phys Med Biol 2017; 62:L9-L19. [PMID: 28665289 DOI: 10.1088/1361-6560/aa7cd5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The use of a phased array of ultrasound transducer elements to sonicate through the skull has opened the way for new treatments and the delivery of therapeutics beyond the blood-brain barrier. The limited steering range of current clinical devices, particularly at higher frequencies, limits the regions of the brain that are considered treatable by ultrasound. A new array design is introduced that allows for high levels of beam steering and increased transmission throughout the brain. These improvements are achieved using concave transducers normal to the outer-skull surface in a patient-specific configuration to target within the skull, so that the far-field of each beam is within the brain. It is shown that by using pulsed ultrasound waves timed to arrive in-phase at the desired target, sufficient levels of acoustic energy are delivered for blood-brain barrier opening throughout the brain.
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Affiliation(s)
- Alec Hughes
- Sunnybrook Research Institute, Physical Sciences Platform, Toronto, M4N 3M5, Canada. Department of Medical Biophysics, University of Toronto, Toronto, Canada
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24
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Sennoga CA, Kanbar E, Auboire L, Dujardin PA, Fouan D, Escoffre JM, Bouakaz A. Microbubble-mediated ultrasound drug-delivery and therapeutic monitoring. Expert Opin Drug Deliv 2016; 14:1031-1043. [DOI: 10.1080/17425247.2017.1266328] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Charles A. Sennoga
- UMR Imagerie et Cerveau, Inserm U930, Université François Rabelais, Tours, France
| | - Emma Kanbar
- UMR Imagerie et Cerveau, Inserm U930, Université François Rabelais, Tours, France
| | - Laurent Auboire
- UMR Imagerie et Cerveau, Inserm U930, Université François Rabelais, Tours, France
| | | | - Damien Fouan
- UMR Imagerie et Cerveau, Inserm U930, Université François Rabelais, Tours, France
| | - Jean-Michel Escoffre
- UMR Imagerie et Cerveau, Inserm U930, Université François Rabelais, Tours, France
| | - Ayache Bouakaz
- UMR Imagerie et Cerveau, Inserm U930, Université François Rabelais, Tours, France
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25
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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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26
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Hynynen K, Jones RM. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy. Phys Med Biol 2016; 61:R206-48. [PMID: 27494561 PMCID: PMC5022373 DOI: 10.1088/0031-9155/61/17/r206] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.
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Affiliation(s)
- Kullervo Hynynen
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada. Department of Medical Biophysics, University of Toronto, Toronto, Canada. Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
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27
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Non-invasive focused ultrasound-based synergistic treatment of brain tumors. JOURNAL OF CANCER RESEARCH AND PRACTICE 2016. [DOI: 10.1016/j.jcrpr.2016.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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28
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Xia J, Tsui PH, Liu HL. Low-Pressure Burst-Mode Focused Ultrasound Wave Reconstruction and Mapping for Blood-Brain Barrier Opening: A Preclinical Examination. Sci Rep 2016; 6:27939. [PMID: 27295608 PMCID: PMC4904799 DOI: 10.1038/srep27939] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 05/27/2016] [Indexed: 11/25/2022] Open
Abstract
Burst-mode focused ultrasound (FUS) exposure has been shown to induce transient blood-brain barrier (BBB) opening for potential CNS drug delivery. FUS-BBB opening requires imaging guidance during the intervention, yet current imaging technology only enables postoperative outcome confirmation. In this study, we propose an approach to visualize short-burst low-pressure focal beam distribution that allows to be applied in FUS-BBB opening intervention on small animals. A backscattered acoustic-wave reconstruction method based on synchronization among focused ultrasound emission, diagnostic ultrasound receiving and passively beamformed processing were developed. We observed that focal beam could be successfully visualized for in vitro FUS exposure with 0.5–2 MHz without involvement of microbubbles. The detectable level of FUS exposure was 0.467 MPa in pressure and 0.05 ms in burst length. The signal intensity (SI) of the reconstructions was linearly correlated with the FUS exposure level both in-vitro (r2 = 0.9878) and in-vivo (r2 = 0.9943), and SI level of the reconstructed focal beam also correlated with the success and level of BBB-opening. The proposed approach provides a feasible way to perform real-time and closed-loop control of FUS-based brain drug delivery.
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Affiliation(s)
- Jingjing Xia
- Department of Electrical Engineering, Chang Gung University, Taoyuan, Taiwan.,Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Po-Hsiang Tsui
- Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.,Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Hao-Li Liu
- Department of Electrical Engineering, Chang Gung University, Taoyuan, Taiwan.,Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
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29
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Abstract
Like cardiovascular disease and cancer, neurological disorders present an increasing challenge for an ageing population. Whereas nonpharmacological procedures are routine for eliminating cancer tissue or opening a blocked artery, the focus in neurological disease remains on pharmacological interventions. Setbacks in clinical trials and the obstacle of access to the brain for drug delivery and surgery have highlighted the potential for therapeutic use of ultrasound in neurological diseases, and the technology has proved useful for inducing focused lesions, clearing protein aggregates, facilitating drug uptake, and modulating neuronal function. In this Review, we discuss milestones in the development of therapeutic ultrasound, from the first steps in the 1950s to recent improvements in technology. We provide an overview of the principles of diagnostic and therapeutic ultrasound, for surgery and transient opening of the blood-brain barrier, and its application in clinical trials of stroke, Parkinson disease and chronic pain. We discuss the promising outcomes of safety and feasibility studies in preclinical models, including rodents, pigs and macaques, and efficacy studies in models of Alzheimer disease. We also consider the challenges faced on the road to clinical translation.
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30
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Promising approaches to circumvent the blood-brain barrier: progress, pitfalls and clinical prospects in brain cancer. Ther Deliv 2015; 6:989-1016. [PMID: 26488496 DOI: 10.4155/tde.15.48] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood-brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are discussed in the context of brain cancer as an example in CNS drug development. Targeting to receptors enabling transport across the BBB offers noninvasive delivery of small molecule and biological cancer therapeutics. Local delivery methods enable high dose delivery while avoiding systemic exposure. BBB disruption with focused ultrasound and microbubbles offers local and noninvasive treatment. Clinical trials show the prospects of these technologies and point to challenges for the future.
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Bing C, Ladouceur-Wodzak M, Wanner CR, Shelton JM, Richardson JA, Chopra R. Trans-cranial opening of the blood-brain barrier in targeted regions using a stereotaxic brain atlas and focused ultrasound energy. J Ther Ultrasound 2014; 2:13. [PMID: 25232482 PMCID: PMC4160001 DOI: 10.1186/2050-5736-2-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/11/2014] [Indexed: 11/13/2022] Open
Abstract
Objective The blood-brain barrier (BBB) protects the brain by preventing the entry of large
molecules; this poses a major obstacle for the delivery of drugs to the brain. A
novel technique using focused ultrasound (FUS) energy combined with microbubble
contrast agents has been widely used for non-invasive trans-cranial BBB opening.
Traditionally, FUS research is conducted with magnetic resonance imaging (MRI)
guidance, which is expensive and poses physical limitations due to the magnetic
field. A system that could allow researchers to test brain therapies without MR
intervention could facilitate and accelerate translational research. Methods In this study, we present a novel FUS system that uses a custom-built FUS
generator mounted on a motorized stereotaxic apparatus with embedded brain atlas
to locally open the BBB in rodents. The system was initially characterized using a
tissue-mimicking phantom. Rodent studies were also performed to evaluate whether
non-invasive, localized BBB opening could be achieved using brain atlas-based
targeting. Brains were exposed to pulsed focused ultrasound energy at
1.06 MHz in rats and 3.23 MHz in mice, with the focal pressure estimated
to be 0.5–0.6 MPa through the skull. BBB opening was confirmed in gross
tissue sections by the presence of Evans blue leakage in the exposed region of the
brain and by histological assessment. Results The targeting accuracy of the stereotaxic system was better than 0.5 mm in
the tissue-mimicking phantom. Reproducible localized BBB opening was verified with
Evans blue dye leakage in 32/33 rats and had a targeting accuracy of
±0.3 mm. The use of higher frequency exposures in mice enabled a similar
precision of localized BBB opening as was observed with the low frequency in the
rat model. Conclusions With this dedicated small-animal motorized stereotaxic-FUS system, we achieved
accurate targeting of focused ultrasound exposures in the brain for non-invasive
opening of the BBB. This system can be used as an alternative to MR-guided FUS and
offers researchers the ability to perform efficient studies (30 min per
experiment including preparation) at a reduced cost in a conventional laboratory
environment.
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Affiliation(s)
- Chenchen Bing
- Department of Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA
| | - Michelle Ladouceur-Wodzak
- Department of Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA
| | - Clinton R Wanner
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA
| | - John M Shelton
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA
| | - James A Richardson
- Department of Pathology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA ; Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA
| | - Rajiv Chopra
- Department of Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9061, USA
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