Design of patient-specific focused ultrasound arrays for non-invasive brain therapy with increased trans-skull transmission and steering range

Hughes, Alec; Hynynen, Kullervo

doi:10.1088/1361-6560/aa7cd5

Cited by 24 publications

(18 citation statements)

References 30 publications

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“…(1) therefore minimizes the spatial exposure to the incident wavefield of the layer embedding the focal point (see Fig. 4), and this could possibly be beneficial for sensitivity analysis and/or safety concern in medical treatment [7].…”

Section: Discussionmentioning

confidence: 99%

Wavefield focusing with reduced cranial invasiveness

Meles

Neut

Dongen

et al. 2019

2019 IEEE International Ultrasonics Symposium (IUS)

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Wavefield focusing can be achieved by Time-Reversal Mirrors, which involve in-and output signals that are infinite in time and waves propagating through the entire medium. Here, an alternative solution for wavefield focusing is presented. This solution is based on a new integral representation where in-and output signals are finite in time, and where the energy of the waves propagating in the layer embedding the focal point is reduced. We explore the potential of the proposed method with numerical experiments involving a 1D example and a cranium model consisting of a skull enclosing a brain.

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Section: Discussionmentioning

confidence: 99%

Wavefield focusing with reduced cranial invasiveness

Meles

Neut

Dongen

et al. 2019

2019 IEEE International Ultrasonics Symposium (IUS)

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“…Focusing zone deflection of transcranial ultrasound has been investigated with spherically focusing phased array (Hughes and Hynynen, 2017). However, deflection with planar phase array remains to be investigated.…”

Section: Simulation Setupmentioning

confidence: 99%

“…Different types of fullwave simulation have been used for transcranial ultrasound. The finite-difference time-domain (FDTD) method, which is a conventional full-wave simulation method (Yılmaz and Çiftçi, 2013), has been used to estimate the velocity of longitudinal and shear waves in the human skull (Hughes and Hynynen, 2017). The Fourier pseudospectral time-domain method, utilizing fast Fourier transform to solve acoustic equations, tends to be more efficient in solving large-scale problems (Liu, 1998;Muñoz and Hornikx, 2017).…”

Section: Introductionmentioning

confidence: 99%

Numerical Evaluation of the Influence of Skull Heterogeneity on Transcranial Ultrasonic Focusing

Jiang

et al. 2020

Front. Neurosci.

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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 phaseaberration 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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“…近年来, 高精度磁共振温度监控朝着三维、实时、高分辨的方面 [82] , 后陆续被批准在骨转移肿瘤 [84] 、前列腺癌 [85] 的治疗中应用. 值得关注的是, 近期FDA批准了磁共振引导聚焦超声系统在特发性震颤 [86] 治疗中的临床应用, 其原理是利用 [87] 以及高效的超声聚焦方法 [88] , 以提高超声在颅内的聚焦效率. 国内外研究组也展开基于短时脉冲声辐射力进行焦点定位的研究 [89~91] , 实验表明, 短时超声脉冲可在脑组织内产生微米级组织位移, 通过磁共振的相位对比技术可对其进行检测; 基于该方法还可进行相控阵阵元相位矫正研究 [88] .…”

Section: 人工声场unclassified