The Stripe Artifact in Transcranial Ultrasound Imaging

Vignon, François; Shi, William T.; Yin, Xiangtao; Hoelscher, Thilo; Powers, Jeff

doi:10.7863/jum.2010.29.12.1779

Cited by 22 publications

(16 citation statements)

References 13 publications

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“…Irregular bone thickness also causes irregular attenuation of insonation [30]. Even with those who present good acoustic windows, the stripe artifact may be seen because of fluid-solid interfaces between the skull and surrounding fluid-like soft tissues [31]. In fact, some volunteers in the present study lacked part of the bone window, particularly in the anterior middle part of the windows.…”

Section: Discussionmentioning

confidence: 94%

Transcranial contrast-enhanced ultrasonography with Sonazoid in semiquantitative evaluation of brain perfusion

2013

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Section: Discussionmentioning

confidence: 94%

Transcranial contrast-enhanced ultrasonography with Sonazoid in semiquantitative evaluation of brain perfusion

2013

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“…The thresholds for dominant SC or IC occur at higher applied acoustic outputs through the skull sample than through the water paths, which is expected as the attenuation from the skull needs to be offset. A lateral gradient of cavitation activities and types can be observed with higher cavitation states and intensities at the center of the image; this can be explained by cosine decrease in power as a function of steering angle from a phased array; this effect is exacerbated through the skull due to the angle-dependent ultrasound attenuation through bone [12]. Dose monitoring: The 'instantaneous doses' of both SC and IC are monitored while increasing the acoustic output from the scanner.…”

Section: Resultsmentioning

confidence: 99%

Real-time two-dimensional imaging of microbubble cavitation

Vignon

Shi

Powers

et al. 2012

AIP Conference Proceedings

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Abstract. Ultrasound cavitation of microbubble contrast agents has a potential for therapeutic applications, including sonothrombolysis in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (e.g. stable versus inertial forms of cavitation) and intensity in and around a treatment area. Acoustic Passive Cavitation Detectors (PCDs) have been used but do not provide spatial information. This paper presents a prototype of a 2D cavitation imager capable of producing images of the dominant cavitation state and intensity in a region of interest at a frame rate of 0.6Hz. The system is based on a modified ultrasound scanner (iE33, Philips) with a sector imaging probe (S5-1). Cavitation imaging is based on the spectral analysis of the acoustic signal radiated by the cavitating microbubbles: ultraharmonics of the excitation frequency indicate stable cavitation, while noise bands indicate inertial cavitation. The system demonstrates the capability to robustly identify stable and inertial cavitation thresholds of Definity microbubbles (Lantheus) in a vessel phantom through 3 ex-vivo human temporal bones, as well as to spatially map cavitation activities.

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“…64,65 The critical angle is defined as:

ξ_{crit} = arcsin (\frac{c_{1}}{c_{2}}),

where in the case of echo reception in transcranial ultrasound, c 1 = 1540 m/s and c 2 = 2500 m/s, yielding ξ crit = 38°. Waves propagate for ξ < ξ crit but are totally internally reflected when ξ = ξ crit .…”

Section: Methodsmentioning

confidence: 99%

“…Beyond this angle, waves may propagate through the skull after experiencing multiple mode conversions. 65 Other researchers have intentionally induced shear mode conversions as a means of overcoming poor acoustic impedance matching in traditional longitudinal wave ultrasound imaging. 13,66,67 In the present work, any element having an angle ξ 1 that exceeds the critical angle after the final iteration is simply disabled.…”

Section: Methodsmentioning

confidence: 99%

Refraction Correction in 3D Transcranial Ultrasound Imaging

Lindsey

Smith

2013

Ultrason Imaging

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We present the first correction of refraction in three-dimensional (3D) ultrasound imaging using an iterative approach that traces propagation paths through a two-layer planar tissue model, applying Snell’s law in 3D. This approach is applied to real-time 3D transcranial ultrasound imaging by precomputing delays offline for several skull thicknesses, allowing the user to switch between three sets of delays for phased array imaging at the push of a button. Simulations indicate that refraction correction may be expected to increase sensitivity, reduce beam steering errors, and partially restore lost spatial resolution, with the greatest improvements occurring at the largest steering angles. Distorted images of cylindrical lesions were created by imaging through an acrylic plate in a tissue-mimicking phantom. As a result of correcting for refraction, lesions were restored to 93.6% of their original diameter in the lateral direction and 98.1% of their original shape along the long axis of the cylinders. In imaging two healthy volunteers, the mean brightness increased by 8.3% and showed no spatial dependency.

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The Stripe Artifact in Transcranial Ultrasound Imaging

Abstract: The stripes are a consequence of the angle-dependent ultrasound transmission and mode conversion at fluid-solid interfaces such as between the skull and the surrounding fluidlike soft tissues.

Cited by 22 publications

References 13 publications

Transcranial contrast-enhanced ultrasonography with Sonazoid in semiquantitative evaluation of brain perfusion

Transcranial contrast-enhanced ultrasonography with Sonazoid in semiquantitative evaluation of brain perfusion

Real-time two-dimensional imaging of microbubble cavitation

Refraction Correction in 3D Transcranial Ultrasound Imaging

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