Bubble Generation by Standing Wave in Water Surrounded by Cranium with Transcranial Ultrasonic Beam

Azuma, Takashi; Kawabata, Ken‐ichi; Umemura, Shin‐ichiro; Ogihara, Makoto; Kubota, Jun; Sasaki, Akira; Furuhata, Hiroshi

doi:10.1143/jjap.44.4625

Cited by 38 publications

(33 citation statements)

References 24 publications

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“…Using an optical technique, Azuma et al (2005) observed similar acoustic patterns attributed to standing waves. We postulate that hemorrhages noted clinically in the contralateral, in clinical trials of ultrasound enhanced thrombolysis, might be due to such standing waves (Daffertshofer et al 2005;Reinhard et al 2006;Wilhelm-Schwenkmezger et al 2007).…”

Section: Discussionmentioning

confidence: 82%

Characterization of Ultrasound Propagation Through Ex-vivo Human Temporal Bone

Ammi

Mast

Huang

et al. 2008

Ultrasound in Medicine & Biology

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Adjuvant therapies that lower the thrombolytic dose or increase its efficacy would represent a significant breakthrough in the treatment of patients with ischemic stroke (Eggers 2006;Tsivgoulis and Alexandrov 2007). The objective of this study was to perform intracranial measurements of the acoustic pressure field generated by 0.12, 1.03 and 2.00 MHz ultrasound transducers to identify optimal ultrasound parameters that would maximize penetration and minimize aberration of the beam. To achieve this goal, in vitro experiments were conducted on five human skull specimens. In a water-filled tank, two unfocused transducers (0.12 and 1.03 MHz) and one focused transducer (2.00 MHz) were consecutively placed near the right temporal bone of each skull. A hydrophone, mounted on a micropositioning system, was moved to an estimated location of the middle cerebral artery (MCA) origin and measurements of the surrounding acoustic pressure field were performed. For each measurement, the distance from the position of maximum acoustic pressure to the estimated origin of the MCA inside the skulls was quantified. The -3 dB depth of field and beam width in the skull were also investigated as a function of the three frequencies. Results show that the transducer alignment relative to the skull is a significant determinant of the detailed behavior of the acoustic field inside the skull. For optimal penetration, insonation normal to the temporal bone was needed. The shape of the 0.12-MHz intracranial beam was more distorted than those at 1.03 and 2.00 MHz due to the large aperture and beam width. However, lower ultrasound pressure reduction was observed at 0.12 MHz (22.5%). At 1.03 and 2.00 MHz two skulls had an insufficient temporal bone window and attenuated the beam severely (up to 96.6% pressure reduction). For all frequencies, constructive and destructive interference patterns were seen near the contralateral skull wall at various elevations. The 0.12-MHz ultrasound beam depth of field was affected the most when passing Corresponding Address: Christy K. Holland, Ph.D., Department of Biomedical Engineering, Colleges of Medicine and Engineering, University of Cincinnati, Medical Science Building, Rm. 6167, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586, USA, Phone: +1 (513) 558-5675, Fax: +1 (513) 558-5958, Christy.Holland@uc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript through the temporal bone and showed a decrease in size of more than 55% on average. The speed of sound in the temporal...

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Section: Discussionmentioning

confidence: 82%

Characterization of Ultrasound Propagation Through Ex-vivo Human Temporal Bone

Ammi

Mast

Huang

et al. 2008

Ultrasound in Medicine & Biology

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“…In addition, the transducers used in the animal experiments by Schneider et al [15] and by Reuter et al [18] were also relatively large (350 mm 2 , about 17.5-fold higher than the LFTUS in the present study). These large transducers result in delivery of much more acoustic energy into the intracranial cavity and increase the formation of dangerous standing waves near the opposite cranium [10,30]. Third, the frequency (≈500 kHz) of our LFTUS was higher than those used in other LFTUS studies (e.g.…”

Section: Discussionmentioning

confidence: 99%

Safety of Low-Frequency Transcranial Ultrasound in Permanent Middle Cerebral Artery Occlusion in Spontaneously Hypertensive Rats

Wang

Fukuda²,

Azuma³

et al. 2011

Cerebrovasc Dis

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Background: Some studies suggest that low-frequency transcranial ultrasound (LFTUS) can enhance thrombolysis, but other studies suggest that it may have adverse effects on intracranial tissues. We previously reported that LFTUS with appropriate parameters was effective and safe in a normotensive rat model of thromboembolic middle cerebral artery occlusion (MCAO) stroke. The goal of this study was to test the safety of this strategy in a spontaneously hypertensive rat (SHR) model of permanent MCAO. Methods: Right MCAO was achieved in male SHRs using intraluminal nylon sutures. Rats exhibiting left hemiparesis were randomly assigned to one of four different groups: (1) normal saline (NS) group (n = 8), intravenous administration of NS as placebo at 3 h after MCAO; (2) NS+LFTUS group (n = 10), NS administration with simultaneous application of LFTUS (480.4 kHz, continuous wave, at an intensity of 0.3 W/cm²) for 1 h; (3) tissue plasminogen activator (tPA) group (n = 11), intravenous administration of alteplase (10 mg/kg body weight) over 1 h instead of NS; or (4) tPA+LFTUS group (n = 11), tPA administration and application of LFTUS. Twenty-four hours after treatment, neurological change was evaluated, and brains were removed and examined histologically. Results: There was no significant difference (p > 0.09) when comparing changes in neurologic status and body weight, infarct ratio, edema ratio, or hemorrhagic transformation among the four groups. Conclusions: Our findings suggest that sonothrombolytic treatment with LFTUS with appropriate parameters is safe when used for the treatment of ischemic stroke in hypertensive rats under the undesired permanent MCAO condition.

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“…The upper limit of the duration time was decided to avoid the effect of standing wave components-for instance, those caused by reflections between a HIFU transducer and HIFU focus or skin surface. This was under the consideration that standing wave components tend to decrease the cavitation threshold [47,48] and may make it difficult to locally generate bubble Appl. Sci.…”

Section: Trigger Hifu Sequencementioning

confidence: 99%

Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

2017

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Abstract:A target tissue can be thermally coagulated in high-intensity focused ultrasound (HIFU) treatment noninvasively. HIFU thermal treatments have been clinically applied to various solid tumors. One of the problems in HIFU treatments is a long treatment time. Acoustically driven microbubbles can accelerate the ultrasonic heating, resulting in the significant reduction of the treatment time. In this paper, a method named "trigger HIFU exposure" which employs cavitation microbubbles is introduced and its results are reviewed. A trigger HIFU sequence consists of high-intensity short pulses followed by moderate-intensity long bursts. Cavitation bubbles induced in a multiple focal regions by rapidly scanning the focus of high-intensity pulses enhanced the temperature increase significantly and produced a large coagulation region with high efficiency.

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Bubble Generation by Standing Wave in Water Surrounded by Cranium with Transcranial Ultrasonic Beam

Cited by 38 publications

References 24 publications

Characterization of Ultrasound Propagation Through Ex-vivo Human Temporal Bone

Characterization of Ultrasound Propagation Through Ex-vivo Human Temporal Bone

Safety of Low-Frequency Transcranial Ultrasound in Permanent Middle Cerebral Artery Occlusion in Spontaneously Hypertensive Rats

Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

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