Refraction Correction in 3D Transcranial Ultrasound Imaging

Lindsey, Brooks D.; Smith, Stephen W.

doi:10.1177/0161734613510287

Cited by 11 publications

(7 citation statements)

References 71 publications

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“…A synthetic aperture imaging (SAI) scheme is used as the transmission of spherical wave fronts facilitates the modeling of refraction (necessary for an accurate phase correction) and provides dynamic focusing in transmission [57]. As explained in [58], modeling the wave propagation through the skull and considering a bone layer with a finite irregular thickness enable the calculation of a unique set of forward and backward travel times, at each pixel, for each transmit beam and for each array element (in receive). As a consequence, we expect our approach to overcome the limitations of nearfield phase-screen methods, in particular, because the concept of isoplanatic patch does not exist in our approach.…”

Section: Introductionmentioning

confidence: 99%

Refraction-Corrected Transcranial Ultrasound Imaging Through the Human Temporal Window Using a Single Probe

Mozaffarzadeh

Verschuur

Verweij

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Transcranial ultrasound imaging (TUI) is a diagnostic modality with numerous applications, but unfortunately, it is hindered by phase aberration caused by the skull. In this article, we propose to reconstruct a transcranial B-mode image with a refraction-corrected synthetic aperture imaging (SAI) scheme. First, the compressional sound velocity of the aberrator (i.e., the skull) is estimated using the bidirectional headwave technique. The medium is described with four layers (i.e., lens, water, skull, and water), and a fast marching method calculates the travel times between individual array elements and image pixels. Finally, a delay-and-sum algorithm is used for image reconstruction with coherent compounding. The point spread function (PSF) in a wire phantom image and reconstructed with the conventional technique (using a constant sound speed throughout the medium), and the proposed method was quantified with numerical synthetic data and experiments with a bone-mimicking plate and a human skull, compared with the PSF achieved in a ground truth image of the medium without the aberrator (i.e., the bone plate or skull). A phasedarray transducer (P4-1, ATL/Philips, 2.5 MHz, 96 elements, pitch = 0.295 mm) was used for the experiments. The results with the synthetic signals, the bone-mimicking plate, and the skull indicated that the proposed method reconstructs the scatterers with an average lateral/axial localization error of 0.06/0.14 mm, 0.11/0.13 mm, and 1.0/0.32 mm,

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Section: Introductionmentioning

confidence: 99%

Refraction-Corrected Transcranial Ultrasound Imaging Through the Human Temporal Window Using a Single Probe

Mozaffarzadeh

Verschuur

Verweij

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…In the context of using ultrasound in the human brain, in imaging and in therapy, the biggest challenge is ultrasonic propagation through the skull. The heterogeneous nature of the human skull bone at a microscopic level, causes considerable distortion of the ultrasonic beam, in the form of resolution compromising reverberations, refraction [22], multiple scattering, reflection between bone and tissue interfaces and mode conversion wth the three latter being the main sources of attenuation [23], while absorption plays a secondary role at the higher frequencies used in imaging [24]. More specifically, the skull thickness, density and equivalent sound velocity tend to vary across the length of the transducer causing phase aberration of the wavefront.…”

Section: Introductionmentioning

confidence: 99%

Super-Resolution Imaging Through the Human Skull

Soulioti

Dayton

Pinton

2020

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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High resolution transcranial ultrasound imaging in humans has been a persistent challenge for ultrasound due to the imaging degradation effects from aberration and reverberation. These mechanisms depend strongly on skull morphology and they have high variability across individuals. Here we demonstrate the feasibility of human transcranial super-resolution imaging using a geometrical focusing approach to concentrate energy at the region of interest, and a phase correction focusing approach that takes the skull morphology into account. It is shown that using the proposed focused method, we can image a 208µm microtube behind a human skull phantom in both an out-of-plane and an in-plane configuration. Individual phase correction profiles for the temporal region of the human skull were calculated and applied to transmit-receive a custom-focused super-resolution imaging sequence through a human skull phantom, targeting the microtube, at 68.5mm in depth, at 2.5 MHz. Microbubble contrast agents were diluted to a concentration of 1.6×10 6 bubbles/mL and perfused through the microtube. It is shown that by correcting for the skull aberration, the RF signal amplitude from the tube improved by a factor of 1.6 in the out-of-plane focused emission case. The lateral registration error of the tube's position, which in the uncorrected case was 990 µm, was reduced to 50µm in the corrected case as measured in the B-mode images. Sensitivity in microbubble detection for the phase corrected case increased by a factor of 1.5 in the out-of-plane imaging case, while in the in-plane case it improved by a factor of 1.3 while achieving an axial registration correction from an initial 1885µm error for the uncorrected emission, to a 284µm error for the corrected counterpart. These findings suggest that super-resolution may be used more generally as a clinical imaging modality in the brain.

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“…In ultrasound imaging, speed-of-sound effects [ 12 , 13 ] and refractive effects have been known to distort the reconstructed geometry, and iterative approaches have been developed to reverse the curvature of ultrasound waves as described by Snell’s law [ 14 , 15 ]. Recently, such corrections have been applied to regions of the body known to harbor strong gradients in refraction index, like the cranium [ 16 ] and the breast [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Surface refraction of sound waves affects calibration of three-dimensional ultrasound

Ballhausen

Ballhausen²,

Lachaı̂ne

et al. 2015

Radiat Oncol

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BackgroundThree-dimensional ultrasound (3D-US) is used in planning and treatment during external beam radiotherapy. The accuracy of the technique depends not only on the achievable image quality in clinical routine, but also on technical limitations of achievable precision during calibration. Refraction of ultrasound waves is a known source for geometric distortion, but such an effect was not expected in homogenous calibration phantoms. However, in this paper we demonstrate that the discontinuity of the refraction index at the phantom surface may affect the calibration unless the ultrasound probe is perfectly perpendicular to the phantom.MethodsA calibration phantom was repeatedly scanned with a 3D-US system (Elekta Clarity) by three independent observers. The ultrasound probe was moved horizontally at a fixed angle in the sagittal plane. The resulting wedge shaped volume between probe and phantom was filled with water to couple in the ultrasound waves. Because the speed of sound in water was smaller than the speed of sound in Zerdine, the main component of the phantom, the angle of the ultrasound waves inside the phantom increased. This caused an apparent shift in the calibration features which was recorded as a function of the impeding angle. To confirm the magnitude and temperature dependence, the experiment was repeated by two of the observers with a mixture of ice and water at 0 °C and with thermalized tap water at 21 °C room temperature.ResultsDuring the first series of measurements, a linear dependency of the displacements dx of the calibration features on the angle α of the ultrasound probe was observed. The three observers recorded significantly nonzero (p < 0.0001) and very consistent slopes of dx/dα of 0.12, 0.12, and 0.13 mm/°, respectively..At 0 °C water temperature, the slope increased to 0.18 ± 0.04 mm/°. This matched the prediction of Snell’s law of 0.185 mm/° for a speed of sound of 1,402 m/s at the melting point of ice.At 21 °C, slopes of 0.11 and 0.12 mm/° were recorded in agreement with the first experiment at about room temperature. The difference to the theoretical expectation of 0.07 mm/° was not significant (p = 0.09).ConclusionsThe surface refraction of sound waves my affect the calibration of three-dimensional ultrasound. The temperature dependence of the effect rules out alternative explanations for the observed shifts in calibration. At room temperature and for a structure that is 10 cm below the water-phantom interface, a tilt of the ultrasound probe of 10° may result in a position reading that is off by more than half a millimeter. Such errors are of the order of other relevant errors typically encountered during the calibration of a 3D-US system. Hence, care must be taken not to tilt the ultrasound probe during calibration.

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Refraction Correction in 3D Transcranial Ultrasound Imaging

Cited by 11 publications

References 71 publications

Refraction-Corrected Transcranial Ultrasound Imaging Through the Human Temporal Window Using a Single Probe

Refraction-Corrected Transcranial Ultrasound Imaging Through the Human Temporal Window Using a Single Probe

Super-Resolution Imaging Through the Human Skull

Surface refraction of sound waves affects calibration of three-dimensional ultrasound

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