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Angla C, Chouh H, Mondou P, Toullelan G, Perlin K, Brulon V, De Schlichting E, Larrat B, Gennisson JL, Chatillon S. New semi-analytical method for fast transcranial ultrasonic field simulation. Phys Med Biol 2024; 69:095017. [PMID: 38537292 DOI: 10.1088/1361-6560/ad3882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/27/2024] [Indexed: 04/25/2024]
Abstract
Objective.To optimize and ensure the safety of ultrasound brain therapy, personalized transcranial ultrasound simulations are very useful. They allow to predict the pressure field, depending on the patient skull and probe position. Most transcranial ultrasound simulations are based on numerical methods which have a long computation time and a high memory usage. The goal of this study is to develop a new semi-analytical field computation method that combines realism and computation speed.Approach.Instead of the classic ray tracing, the ultrasonic paths are computed by time of flight minimization. Then the pressure field is computed using the pencil method. This method requires a smooth and homogeneous skull model. The simulation algorithm, so-called SplineBeam, was numerically validated, by comparison with existing solvers, and experimentally validated by comparison with hydrophone measured pressure fields through anex vivohuman skull.Main results.SplineBeam simulated pressure fields were close to the experimentally measured ones, with a focus position difference of the order of the positioning error and a maximum pressure difference lower than 6.02%. In addition, for those configurations, SplineBeam computation time was lower than another simulation software, k-Wave's, by two orders of magnitude, thanks to its capacity to compute the field only at the focal spot.Significance.These results show the potential of this new method to compute fast and realistic transcranial pressure fields. The combination of this two assets makes it a promising tool for real time transcranial pressure field prediction during ultrasound brain therapy interventions.
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Affiliation(s)
- C Angla
- Université Paris-Saclay, CEA List, F-91120, Palaiseau, France
- Université Paris-Saclay, CNRS, Inserm, CEA, BioMaps, F-91190, Orsay, France
| | - H Chouh
- Université Paris-Saclay, CEA List, F-91120, Palaiseau, France
| | - P Mondou
- Université Paris-Saclay, CNRS, CEA, Neurospin F-91191, Gif-sur-Yvette, France
| | - G Toullelan
- Université Paris-Saclay, CEA List, F-91120, Palaiseau, France
| | - K Perlin
- Université Paris-Saclay, CEA List, F-91120, Palaiseau, France
| | - V Brulon
- Université Paris-Saclay, CNRS, Inserm, CEA, BioMaps, F-91190, Orsay, France
| | - E De Schlichting
- CHU Grenoble-Alpes, Service de Neurochirurgie, F-38700, Grenoble, France
| | - B Larrat
- Université Paris-Saclay, CNRS, CEA, Neurospin F-91191, Gif-sur-Yvette, France
| | - J-L Gennisson
- Université Paris-Saclay, CNRS, Inserm, CEA, BioMaps, F-91190, Orsay, France
| | - S Chatillon
- Université Paris-Saclay, CEA List, F-91120, Palaiseau, France
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Angla C, Larrat B, Gennisson JL, Chatillon S. Transcranial ultrasound simulations: A review. Med Phys 2023; 50:1051-1072. [PMID: 36047387 DOI: 10.1002/mp.15955] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 11/06/2022] Open
Abstract
Transcranial ultrasound is more and more used for therapy and imaging of the brain. However, the skull is a highly attenuating and aberrating medium, with different structures and acoustic properties among samples and even within a sample. Thus, case-specific simulations are needed to perform transcranial focused ultrasound interventions safely. In this article, we provide a review of the different methods used to model the skull and to simulate ultrasound propagation through it.
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Affiliation(s)
| | - Benoit Larrat
- Université Paris Saclay, CNRS, CEA, DRF/JOLIOT/NEUROSPIN/BAOBAB, Gif-sur-Yvette, France
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Montanaro H, Pasquinelli C, Lee HJ, Kim H, Siebner HR, Kuster N, Thielscher A, Neufeld E. The impact of CT image parameters and skull heterogeneity modeling on the accuracy of transcranial focused ultrasound simulations. J Neural Eng 2021; 18. [PMID: 33836508 DOI: 10.1088/1741-2552/abf68d] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 04/09/2021] [Indexed: 11/12/2022]
Abstract
Objective. Low-intensity transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation (NIBS) technique. TUS can reach deeper areas and target smaller regions in the brain than other NIBS techniques, but its application in humans is hampered by the lack of a straightforward and reliable procedure to predict the induced ultrasound exposure. Here, we examined how skull modeling affects computer simulations of TUS.Approach. We characterized the ultrasonic beam after transmission through a sheep skull with a hydrophone and performed computed tomography (CT) image-based simulations of the experimental setup. To study the skull model's impact, we varied: CT acquisition parameters (tube voltage, dose, filter sharpness), image interpolation, segmentation parameters, acoustic property maps (speed-of-sound, density, attenuation), and transducer-position mismatches. We compared the impact of modeling parameter changes on model predictions and on measurement agreement. Spatial-peak intensity and location, total power, and the Gamma metric (a measure for distribution differences) were used as quantitative criteria. Modeling-based sensitivity analysis was also performed for two human head models.Main results. Sheep skull attenuation assignment and transducer positioning had the most important impact on spatial peak intensity (overestimation up to 300%, respectively 30%), followed by filter sharpness and tube voltage (up to 20%), requiring calibration of the mapping functions. Positioning and skull-heterogeneity-structure strongly affected the intensity distribution (gamma tolerances exceeded in>80%, respectively>150%, of the focus-volume in water), necessitating image-based personalized modeling. Simulation results in human models consistently demonstrate a high sensitivity to the skull-heterogeneity model, attenuation tuning, and transducer shifts, the magnitude of which depends on the underlying skull structure complexity.Significance. Our study reveals the importance of properly modeling the skull-heterogeneity and its structure and of accurately reproducing the transducer position. The results raise red flags when translating modeling approaches among clinical sites without proper standardization and/or recalibration of the imaging and modeling parameters.
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Affiliation(s)
- Hazael Montanaro
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.,Department of Information Technology and Electrical Engineering , Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Laboratory for Acoustics/Noise Control, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Dubendorf, Switzerland.,The authors contributed equally to the work
| | - Cristina Pasquinelli
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital - Amager and Hvidovre, Copenhagen, Denmark.,Center for Magnetic Resonance, Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark.,The authors contributed equally to the work
| | - Hyunjoo J Lee
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Hyunggug Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Hartwig R Siebner
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital - Amager and Hvidovre, Copenhagen, Denmark.,Department of Neurology , Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark.,Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen, Denmark
| | - Niels Kuster
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.,Department of Information Technology and Electrical Engineering , Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Axel Thielscher
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital - Amager and Hvidovre, Copenhagen, Denmark.,Center for Magnetic Resonance, Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Esra Neufeld
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.,Department of Information Technology and Electrical Engineering , Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
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Pursiainen S, Lew S, Wolters CH. Forward and inverse effects of the complete electrode model in neonatal EEG. J Neurophysiol 2016; 117:876-884. [PMID: 27852731 PMCID: PMC5338621 DOI: 10.1152/jn.00427.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 11/10/2016] [Indexed: 11/24/2022] Open
Abstract
The effect of the complete electrode model on electroencephalography forward and inverse computations is explored. A realistic neonatal head model, including a skull structure with fontanels and sutures, is used. The electrode and skull modeling differences are analyzed and compared with each other. The results suggest that the complete electrode model can be considered as an integral part of the outer head model. To achieve optimal source localization results, accurate electrode modeling might be necessary. This paper investigates finite element method-based modeling in the context of neonatal electroencephalography (EEG). In particular, the focus lies on electrode boundary conditions. We compare the complete electrode model (CEM) with the point electrode model (PEM), which is the current standard in EEG. In the CEM, the voltage experienced by an electrode is modeled more realistically as the integral average of the potential distribution over its contact surface, whereas the PEM relies on a point value. Consequently, the CEM takes into account the subelectrode shunting currents, which are absent in the PEM. In this study, we aim to find out how the electrode voltage predicted by these two models differ, if standard size electrodes are attached to a head of a neonate. Additionally, we study voltages and voltage variation on electrode surfaces with two source locations: 1) next to the C6 electrode and 2) directly under the Fz electrode and the frontal fontanel. A realistic model of a neonatal head, including a skull with fontanels and sutures, is used. Based on the results, the forward simulation differences between CEM and PEM are in general small, but significant outliers can occur in the vicinity of the electrodes. The CEM can be considered as an integral part of the outer head model. The outcome of this study helps understanding volume conduction of neonatal EEG, since it enlightens the role of advanced skull and electrode modeling in forward and inverse computations. NEW & NOTEWORTHY The effect of the complete electrode model on electroencephalography forward and inverse computations is explored. A realistic neonatal head model, including a skull structure with fontanels and sutures, is used. The electrode and skull modeling differences are analyzed and compared with each other. The results suggest that the complete electrode model can be considered as an integral part of the outer head model. To achieve optimal source localization results, accurate electrode modeling might be necessary.
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Affiliation(s)
- S Pursiainen
- Department of Mathematics, Tampere University of Technology, Tampere, Finland;
| | - S Lew
- Newborn Medicine in the Boston Children's Hospital, Boston, Massachusetts.,Department of Engineering, Olivet Nazarene University, Bourbonnais, Illinois; and
| | - C H Wolters
- Institute for Biomagnetism and Biosignalanalysis, University of Münster, Münster, Germany
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