Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331398
M. Leite, P. Figueiredo, A. Leal
In this work, a new approach to simultaneous Electroencephalography correlated Functional Magnetic Imaging (EEG-fMRI) data processing in epilepsy is introduced. Independent component analysis decomposition was performed on EEG data and multiple model based metrics were applied to the resulting time courses, these were then used to predict the fMRI data. When compared with the conventional fMRI data analysis based on square waveform descriptions of seizure activity, more significant activations were found with the method proposed here, for the four patients studied. In general, the results were consistent with the neurophysiologist's expectation, but further validation using more direct measurements of seizure activity is necessary. A detailed study on the hemodynamic response function (HRF) to the EEG metrics was performed for one patient. The HRFs estimated were broader than the canonical HRF and the distributions of its delay and dispersion were mapped throughout the subject's brain.
{"title":"Estimation of the haemodynamic response to epileptic activity in EEG-fMRI data","authors":"M. Leite, P. Figueiredo, A. Leal","doi":"10.1109/ENBENG.2012.6331398","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331398","url":null,"abstract":"In this work, a new approach to simultaneous Electroencephalography correlated Functional Magnetic Imaging (EEG-fMRI) data processing in epilepsy is introduced. Independent component analysis decomposition was performed on EEG data and multiple model based metrics were applied to the resulting time courses, these were then used to predict the fMRI data. When compared with the conventional fMRI data analysis based on square waveform descriptions of seizure activity, more significant activations were found with the method proposed here, for the four patients studied. In general, the results were consistent with the neurophysiologist's expectation, but further validation using more direct measurements of seizure activity is necessary. A detailed study on the hemodynamic response function (HRF) to the EEG metrics was performed for one patient. The HRFs estimated were broader than the canonical HRF and the distributions of its delay and dispersion were mapped throughout the subject's brain.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131376992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331358
G. Clemente, V. Alves, A. Abrunhosa
Carbon-11 is a positron emitting nuclide that has been used extensively to label compounds destined for molecular targets in the brain. Pittsburgh compound B ([11C]PiB) is a benzothiazole derivative of thioflavin T that is used to image beta-amyloid deposits in Alzheimer's disease patients with Positron Emission Tomography (PET). In this paper we report on the optimization of a fully automated synthesis, purification and reformulation of [11C]PiB suitable for use in human PET studies. [11C]PiB was prepared from 2-(4'-aminophenyl)-6-hydroxybenzothiazole by [11C]-methylation with methyl triflate reacting in an high-performance liquid chromatography (HPLC) loop, purified and reformulated by solid phase extraction. The specific activity of [11C]PiB was 25 ± 10 GBq/μmol, and radiochemical purity was better than 95%.
{"title":"Synthesis optimization of pittsburgh compound B by the captive solvent method","authors":"G. Clemente, V. Alves, A. Abrunhosa","doi":"10.1109/ENBENG.2012.6331358","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331358","url":null,"abstract":"Carbon-11 is a positron emitting nuclide that has been used extensively to label compounds destined for molecular targets in the brain. Pittsburgh compound B ([11C]PiB) is a benzothiazole derivative of thioflavin T that is used to image beta-amyloid deposits in Alzheimer's disease patients with Positron Emission Tomography (PET). In this paper we report on the optimization of a fully automated synthesis, purification and reformulation of [11C]PiB suitable for use in human PET studies. [11C]PiB was prepared from 2-(4'-aminophenyl)-6-hydroxybenzothiazole by [11C]-methylation with methyl triflate reacting in an high-performance liquid chromatography (HPLC) loop, purified and reformulated by solid phase extraction. The specific activity of [11C]PiB was 25 ± 10 GBq/μmol, and radiochemical purity was better than 95%.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132442211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331363
R. Faustino, A. Abrunhosa, M. Castelo‐Branco
In this paper we report on the progress of our research regarding the effects of high magnetic fields in the development of an intact living organism, the nematode Ceanorhabditis elegans. The objective is to observe details of possible changes in morphology and neurobiology during the development process. Results obtained so far with fields up to 14 Tesla failed to show any statistically significant alterations.
{"title":"Neuronal and developmental effects of high magnetic fields in the development of an intact living organism: Ceanorhabditis elegans","authors":"R. Faustino, A. Abrunhosa, M. Castelo‐Branco","doi":"10.1109/ENBENG.2012.6331363","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331363","url":null,"abstract":"In this paper we report on the progress of our research regarding the effects of high magnetic fields in the development of an intact living organism, the nematode Ceanorhabditis elegans. The objective is to observe details of possible changes in morphology and neurobiology during the development process. Results obtained so far with fields up to 14 Tesla failed to show any statistically significant alterations.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133514222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331399
Teresa Sousa, P. Mendes, José Ribeiro
Rhythms analysis is a quantitative analysis tool that detects only the spectral patterns of rhythmical activity present on the electroencephalography (EEG) and therefore is very important on seizure detection. In the hospital of S. João, a high amount of EEG records are performed both in the routine EEG and intensive care units (ICU). On November 2009, began in this hospital the study of the impact of the rhythm analysis technique in the electrographic (EEG) seizure detection. The rhythms analysis technique was applied in routine cases and in continuous monitoring cases on adults and neonate patients. The sensitivity, specificity, positive predicted value and negative predicted value of the rhythms analysis in the seizure detection were estimated. The rhythms analysis presented good results as an auxiliary system on the epilepsy cases diagnosed based on the EEG.
节律分析是一种定量分析工具，仅检测脑电图(EEG)上存在的节律活动的频谱模式，因此在癫痫发作检测中非常重要。在S. jo o医院，在常规脑电图和重症监护病房(ICU)都进行了大量的脑电图记录。2009年11月，本院开始研究心律分析技术在脑电图(EEG)癫痫发作检测中的作用。节律分析技术应用于常规病例和成人及新生儿连续监测病例。估计心律分析在癫痫发作检测中的敏感性、特异性、阳性预测值和阴性预测值。节律分析作为一种辅助系统，对脑电图诊断的癫痫患者效果良好。
{"title":"The impact of rhythms analysis technique on electrographic seizure detection (EEG)","authors":"Teresa Sousa, P. Mendes, José Ribeiro","doi":"10.1109/ENBENG.2012.6331399","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331399","url":null,"abstract":"Rhythms analysis is a quantitative analysis tool that detects only the spectral patterns of rhythmical activity present on the electroencephalography (EEG) and therefore is very important on seizure detection. In the hospital of S. João, a high amount of EEG records are performed both in the routine EEG and intensive care units (ICU). On November 2009, began in this hospital the study of the impact of the rhythm analysis technique in the electrographic (EEG) seizure detection. The rhythms analysis technique was applied in routine cases and in continuous monitoring cases on adults and neonate patients. The sensitivity, specificity, positive predicted value and negative predicted value of the rhythms analysis in the seizure detection were estimated. The rhythms analysis presented good results as an auxiliary system on the epilepsy cases diagnosed based on the EEG.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114723186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331367
A. João, A. Gambaruto, A. Sequeira
Many of the diseases affecting the cardiovascular system include a variety of disorders and conditions that are related in part to the haemodynamics, as well as genetic predisposition and biochemistry amongst others. With respect to the haemodynamics, the commonly sought factors are near-wall mechanical properties including wall shear stress (and derived parameters) and transport phenomena, such as mixing and mass transport. These factors are susceptible to large variations amongst individuals, and in order to perform accurate clinical evaluation careful interpretation of patient specific information is required. Taking an example of a configuration of the aorto-illiac bifurcation, we examine the effects of image filtering and contrast enhancement on the reconstructed geometry and the resulting computed haemodynamics. The algorithms used to quantify the processed images are based on pixel intensity variance, peak signal-to-noise ratio and segmentation. In this study we focus on the effects of uncertainty in clinically acquired medical images to the variability in the reconstructed vessel geometry, and the subsequent error propagation to the computed haemodynamics with emphasis on factors related to diseased states.
{"title":"The effects of medical image processing techniques on the computational haemodynamics","authors":"A. João, A. Gambaruto, A. Sequeira","doi":"10.1109/ENBENG.2012.6331367","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331367","url":null,"abstract":"Many of the diseases affecting the cardiovascular system include a variety of disorders and conditions that are related in part to the haemodynamics, as well as genetic predisposition and biochemistry amongst others. With respect to the haemodynamics, the commonly sought factors are near-wall mechanical properties including wall shear stress (and derived parameters) and transport phenomena, such as mixing and mass transport. These factors are susceptible to large variations amongst individuals, and in order to perform accurate clinical evaluation careful interpretation of patient specific information is required. Taking an example of a configuration of the aorto-illiac bifurcation, we examine the effects of image filtering and contrast enhancement on the reconstructed geometry and the resulting computed haemodynamics. The algorithms used to quantify the processed images are based on pixel intensity variance, peak signal-to-noise ratio and segmentation. In this study we focus on the effects of uncertainty in clinically acquired medical images to the variability in the reconstructed vessel geometry, and the subsequent error propagation to the computed haemodynamics with emphasis on factors related to diseased states.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115783338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331376
S. Silva, C. Loureiro, H. Almeida, I. Otel, J. Domingues, J. S. Silva, M. Quadrado, A. M. Morgado
The evaluation of corneal nerve morphology by optical methods may form the basis of a simple, non-invasive technique for early diagnosis and accurate assessment of peripheral diabetic neuropathy. Currently, corneal nerves can be imaged in vivo using corneal confocal microscopy, an expensive technique that is only available at large medical units. Our goal is to develop an optical technique for peripheral neuropathy assessment, through corneal nerves imaging, based on simple, easy to operate and widespread instrumentation. This technique will be built upon automatic algorithms for corneal nerves segmentation and morphometric analysis and an optical confocal module for recording corneal nerves images using a standard slit-lamp, the most commonly used instrument in ophthalmic practice to observe the anterior eye. Here we present the current status and results of this ongoing project.
{"title":"Evaluation of corneal nerves morphology for diabetic peripheral neuropathy assessment","authors":"S. Silva, C. Loureiro, H. Almeida, I. Otel, J. Domingues, J. S. Silva, M. Quadrado, A. M. Morgado","doi":"10.1109/ENBENG.2012.6331376","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331376","url":null,"abstract":"The evaluation of corneal nerve morphology by optical methods may form the basis of a simple, non-invasive technique for early diagnosis and accurate assessment of peripheral diabetic neuropathy. Currently, corneal nerves can be imaged in vivo using corneal confocal microscopy, an expensive technique that is only available at large medical units. Our goal is to develop an optical technique for peripheral neuropathy assessment, through corneal nerves imaging, based on simple, easy to operate and widespread instrumentation. This technique will be built upon automatic algorithms for corneal nerves segmentation and morphometric analysis and an optical confocal module for recording corneal nerves images using a standard slit-lamp, the most commonly used instrument in ophthalmic practice to observe the anterior eye. Here we present the current status and results of this ongoing project.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121318466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-03-26DOI: 10.1109/ENBENG.2012.6331373
T. Santos, L. Ribeiro, C. Lobo, Rui Bernardes, P. Serranho
Optical coherence tomography (OCT) is becoming one of the most important imaging modalities in ophthalmology due to its noninvasiveness and resolution. Besides allowing the visualization the human retina structure in detail, it was recently proposed that OCT embeds functional information. Specifically, it was proposed that blood-retinal barrier status information is present within OCT data acquired from the human retina. We herewith present the validation of previous work on the possibility to discriminate between eyes of healthy volunteers and eyes of patients with diabetic retinopathy resorting to a supervised classification procedure, the support vector machine (SVM) classifier, based solely on the statistics of the distribution of retinal human OCT data. For this purpose, we calculate the chance line and the statistical significance for the dependence between the supervised classification and their respective discrimination results. Furthermore, a genetic algorithm is used to find optimum kernel and regularization parameters for the radial basis function kernel of the SVM classifier. Achieved results strengthen the possibility that information on the health status of the blood-retinal barrier is encoded within the optical properties of the human retina.
{"title":"Validation of the automatic identification of eyes with diabetic retinopathy by OCT","authors":"T. Santos, L. Ribeiro, C. Lobo, Rui Bernardes, P. Serranho","doi":"10.1109/ENBENG.2012.6331373","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331373","url":null,"abstract":"Optical coherence tomography (OCT) is becoming one of the most important imaging modalities in ophthalmology due to its noninvasiveness and resolution. Besides allowing the visualization the human retina structure in detail, it was recently proposed that OCT embeds functional information. Specifically, it was proposed that blood-retinal barrier status information is present within OCT data acquired from the human retina. We herewith present the validation of previous work on the possibility to discriminate between eyes of healthy volunteers and eyes of patients with diabetic retinopathy resorting to a supervised classification procedure, the support vector machine (SVM) classifier, based solely on the statistics of the distribution of retinal human OCT data. For this purpose, we calculate the chance line and the statistical significance for the dependence between the supervised classification and their respective discrimination results. Furthermore, a genetic algorithm is used to find optimum kernel and regularization parameters for the radial basis function kernel of the SVM classifier. Achieved results strengthen the possibility that information on the health status of the blood-retinal barrier is encoded within the optical properties of the human retina.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131854203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-03-26DOI: 10.1109/ENBENG.2012.6331372
P. Rodrigues, T. Santos, H. Pereira, J. Figueira, Rui Bernardes
This work aims to discriminate between healthy eyes and eyes at risk of developing idiopathic macular hole (IMH). Fits of well known mathematical functions were used to model the topography of the retina with special emphasis on the foveal depression. Based on this set of fits, we are able to describe and, therefore, to analyze the shape of the retinal surface. The working hypothesis is that differences can be found within the parameters of the set of functions used to describe the retinal topography between the two groups of eyes. We have resorted to a pattern classification support vector machine algorithm to discriminate between groups through training using known cases.
{"title":"Identification of eyes at risk of developing idiopathic macular holes by support vector machines","authors":"P. Rodrigues, T. Santos, H. Pereira, J. Figueira, Rui Bernardes","doi":"10.1109/ENBENG.2012.6331372","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331372","url":null,"abstract":"This work aims to discriminate between healthy eyes and eyes at risk of developing idiopathic macular hole (IMH). Fits of well known mathematical functions were used to model the topography of the retina with special emphasis on the foveal depression. Based on this set of fits, we are able to describe and, therefore, to analyze the shape of the retinal surface. The working hypothesis is that differences can be found within the parameters of the set of functions used to describe the retinal topography between the two groups of eyes. We have resorted to a pattern classification support vector machine algorithm to discriminate between groups through training using known cases.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134077721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-07-01DOI: 10.1109/ENBENG.2012.6331390
Carla Maria, Nunes Lopes, A. Rego, Resumo Vii
Metabolic dysfunction is relatively common in Huntington's disease (HD) patients and in HD transgenic mouse models. The YAC128 mice express full-length mutant huntingtin (mHtt) with 128 glutamines and manifest a phenotype close to HD patients. The objective of our study was to evaluate the effect of an hyperglycemic background on peripheral and central metabolic parameters in YAC128 mice versus wild-type littermates. Both YAC128 and WT mice exhibited elevated fasting and non-fasting plasma glucose levels, but no significant change in body weight or metabolic parameters were found. However, in Insulin Tolerance Test, YAC128 mice showed significantly higher glucose values, compared to WT mice. The HD mice also showed a tendency to impairment in motor coordination and balance. In YAC128 mice, plasma or brain levels of IGF-1 and insulin were not significantly changed, although there was a tendency for a decrease in insulin. Moreover, a reduction in energy charge and higher lactate/pyruvate ratio were detected in HD brain. These data suggest that expression of full-length mHtt in hyperglycémie background may induce both peripheral and central metabolic changes.
{"title":"Peripheral and cerebral metabolic features in an animal model of Huntington's disease","authors":"Carla Maria, Nunes Lopes, A. Rego, Resumo Vii","doi":"10.1109/ENBENG.2012.6331390","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331390","url":null,"abstract":"Metabolic dysfunction is relatively common in Huntington's disease (HD) patients and in HD transgenic mouse models. The YAC128 mice express full-length mutant huntingtin (mHtt) with 128 glutamines and manifest a phenotype close to HD patients. The objective of our study was to evaluate the effect of an hyperglycemic background on peripheral and central metabolic parameters in YAC128 mice versus wild-type littermates. Both YAC128 and WT mice exhibited elevated fasting and non-fasting plasma glucose levels, but no significant change in body weight or metabolic parameters were found. However, in Insulin Tolerance Test, YAC128 mice showed significantly higher glucose values, compared to WT mice. The HD mice also showed a tendency to impairment in motor coordination and balance. In YAC128 mice, plasma or brain levels of IGF-1 and insulin were not significantly changed, although there was a tendency for a decrease in insulin. Moreover, a reduction in energy charge and higher lactate/pyruvate ratio were detected in HD brain. These data suggest that expression of full-length mHtt in hyperglycémie background may induce both peripheral and central metabolic changes.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124304893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/enbeng.2012.6331375
H. Oliveira, M. Dias Silva, C. V. Ferreira, P. Fonte, L. Jesus, R. Salvador, J. Silvestre, P. Crespo
We present a system comprising multiple coils excited at a single frequency and immersed in a conducting liquid allowing for unprecedented deep, whole-brain transcranial magnetic stimulation (TMS). Finite-element methods were applied onto a spherical head model complemented by an ellipsoidal torso. The head model comprises skin, skull, cerebral spinal fluid, and brain tissue. Results show deep-brain induced currents reaching 85% at 10-cm penetration (brain center) in respect to surface (cortex) maximum. For comparison, state-of-the-art published data reach 47% relative induction at 8-cm depth only. This system counterparts well-known limiting effects occurring due to the enhancement of current densities at the brain/surface interface by immersing the stimulating coils (and partially the head of the patient) into a conducting liquid such as an electrolyte solution or a liquid metal. In addition, several system asymmetries are exploited in order to optimize deep-brain stimulation down to the center of the brain. Although current densities induced in the retinas and in the torso are estimated to reach sub-optimum levels in regard to patient safety, these first positive results show that overcoming the brain/surface induction barrier is feasible.
{"title":"Multiple coils in a conducting liquid for deep and whole-brain transcranial magnetic stimulation. I. Single-frequency excitation","authors":"H. Oliveira, M. Dias Silva, C. V. Ferreira, P. Fonte, L. Jesus, R. Salvador, J. Silvestre, P. Crespo","doi":"10.1109/enbeng.2012.6331375","DOIUrl":"https://doi.org/10.1109/enbeng.2012.6331375","url":null,"abstract":"We present a system comprising multiple coils excited at a single frequency and immersed in a conducting liquid allowing for unprecedented deep, whole-brain transcranial magnetic stimulation (TMS). Finite-element methods were applied onto a spherical head model complemented by an ellipsoidal torso. The head model comprises skin, skull, cerebral spinal fluid, and brain tissue. Results show deep-brain induced currents reaching 85% at 10-cm penetration (brain center) in respect to surface (cortex) maximum. For comparison, state-of-the-art published data reach 47% relative induction at 8-cm depth only. This system counterparts well-known limiting effects occurring due to the enhancement of current densities at the brain/surface interface by immersing the stimulating coils (and partially the head of the patient) into a conducting liquid such as an electrolyte solution or a liquid metal. In addition, several system asymmetries are exploited in order to optimize deep-brain stimulation down to the center of the brain. Although current densities induced in the retinas and in the torso are estimated to reach sub-optimum levels in regard to patient safety, these first positive results show that overcoming the brain/surface induction barrier is feasible.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121325577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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