The effects of temporal bone on transcranial Doppler ultrasound beam shape

Deverson, Stephanie; Evans, David H.; Bouch, D C

doi:10.1016/s0301-5629(99)00129-5

Cited by 30 publications

(16 citation statements)

References 19 publications

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“…The US field refraction induced by bone has been the subject of many studies (for some examples see: Moehring and Ritcey (1996), Deverson et al (2000) and Evans (2006) and our work complementing these previous studies. This research has been crucial because it has been shown by Girault et al (2010) that microembolus trajectories depend on both the shape of the US beam and the spatial velocity distribution.…”

Section: Mapping Of the Pressure Fieldsupporting

confidence: 68%

“…When the middle cerebral artery is viewed from the temporal bone, the blood flow is mainly parallel to the ultrasound beam axis. A detailed discussion of the influence of the temporal bone on the ultrasound (US) beam is presented in Deverson et al (2000). However, we showed in this study that, although the US beam was attenuated and distorted, the radiation force induced was sufficient to move microbubbles.…”

Section: Introductionmentioning

confidence: 69%

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Analysis of Index Modulation of Doppler Microembolic Signals Part II: In Vitro Discrimination

Girault¹,

Kouamé²,

Ménigot³

et al. 2011

Ultrasound in Medicine & Biology

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The purpose of this study was to validate through experiments that frequency modulation (FM) of microembolic signatures was principally due to the radiation force. Several experiments were required to prove that such a frequency modulation originates from microdisplacements induced by the radiation force acting on microbubbles. The first experiment was performed to verify that the diffraction effects due to the presence of a skull did not disturb the acoustic field appreciably and to validate that a radiation force in the brain was sufficient to create a detectable microdisplacement. A second in vitro experiment using a single gate transcranial Doppler (TCD) system was conducted to show discrimination feasibility and to check that microembolic frequency modulation signatures (FMS) and frequency modulation index (FMI) were the same as those observed in vivo and those calculated by simulation. A final in vitro experiment was performed using a multigate multichannel TCD system to confirm the second experiment by directly measuring the microdisplacement induced by the radiation force. A new parameter, to be known as the position modulation index (PMI), is proposed. We showed that the radiation force is sufficient to induce detectable microdisplacements despite the presence of the skull. We also showed that the diffraction effects due to the skull induced a decrease in the ultrasound beam of 7.6 dB. Finally, we showed by using FMI and PMI that it is possible to discriminate gaseous from formed elements (<100 microns) despite the presence of the skull. The discrimination based on the FMI is an off-line technique allowing the analysis of standard TCD recordings. However, discrimination based on the PMI requires recordings obtained exclusively from a multi-gate system.

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Section: Mapping Of the Pressure Fieldsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 69%

Analysis of Index Modulation of Doppler Microembolic Signals Part II: In Vitro Discrimination

Girault¹,

Kouamé²,

Ménigot³

et al. 2011

Ultrasound in Medicine & Biology

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“…Transcranial ultrasonic brain imaging of adults is also limited by the inhomogeneous aberrating effect of the skull bone. [3][4][5][6][7][8][9] The skull bone induces both phase and amplitude distortions. Such distortions can be potentially corrected by various methods, such as adaptive focusing, 10 time reversal, 11 dynamic focusing, 12 and spatiotemporal inverse filter ͑STIF͒.…”

Section: Introductionmentioning

confidence: 99%

Monkey brain cortex imaging by photoacoustic tomography

Yang

Wang

2008

J. Biomed. Opt.

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Abstract. Photoacoustic tomography ͑PAT͒ is applied to image the brain cortex of a monkey through the intact scalp and skull ex vivo. The reconstructed PAT image shows the major blood vessels on the monkey brain cortex. For comparison, the brain cortex is imaged without the scalp, and then imaged again without the scalp and skull. Ultrasound attenuation through the skull is also measured at various incidence angles. This study demonstrates that PAT of the brain cortex is capable of surviving the ultrasound signal attenuation and distortion caused by a relatively thick skull.

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“…Beam refraction, reduction in beam width, multiple regions of high intensities within the same soundfield and wide ranges of energy losses in different skull samples occur (Fry and Barger 1978;Grolimund 1986;White et al 1978). The distortion effects as a result of insonation through temporal bone are variable and unpredictable and their appearance seem to be independent from the ultrasound device itself (Deverson et al 2000). Substantial work on trans-skull phase distortion and signal absorption has been done (Aarnio et al 2005;White et al 2005White et al , 2006Yin and Hynynen 2005).…”

Section: Introductionmentioning

confidence: 99%