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Angel V. Peterchev - One of the best experts on this subject based on the ideXlab platform.

  • electric field model of transcranial electric stimulation in nonhuman primates correspondence to individual motor threshold
    IEEE Transactions on Biomedical Engineering, 2015
    Co-Authors: Won Hee Lee, Sarah H. Lisanby, Andrew F Laine, Angel V. Peterchev
    Abstract:

    Objective: To develop a pipeline for realistic head models of nonhuman primates (NHPs) for simulations of noninvasive brain stimulation, and use these models together with empirical threshold measurements to demonstrate that the models capture individual Anatomical Variability. Methods: Based on structural MRI data, we created models of the electric field (E-field) induced by right unilateral (RUL) electroconvulsive therapy (ECT) in four rhesus macaques. Individual motor threshold (MT) was measured with transcranial electric stimulation (TES) administered through the RUL electrodes in the same subjects. Results: The interindividual Anatomical differences resulted in 57% variation in median E-field strength in the brain at fixed stimulus current amplitude. Individualization of the stimulus current by MT reduced the E-field variation in the target motor area by 27%. There was significant correlation between the measured MT and the ratio of simulated electrode current and E-field strength ( $r^{2} = 0.95$ , $p = 0.026$ ). Exploratory analysis revealed significant correlations of this ratio with Anatomical parameters including of the superior electrode-to-cortex distance, vertex-to-cortex distance, and brain volume ( $r^{2} > 0.96$ , $p ). The neural activation threshold was estimated to be $0.45 \pm 0.07$ V/cm for 0.2-ms stimulus pulse width. Conclusion: These results suggest that our individual-specific NHP E-field models appropriately capture individual Anatomical Variability relevant to the dosing of TES/ECT. These findings are exploratory due to the small number of subjects. Significance: This study can contribute insight in NHP studies of ECT and other brain stimulation interventions, help link the results to clinical studies, and ultimately lead to more rational brain stimulation dosing paradigms.

  • Effect of Anatomical Variability on Electric Field Characteristics of Electroconvulsive Therapy and Magnetic Seizure Therapy: A Parametric Modeling Study
    IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society, 2014
    Co-Authors: Zhide Deng, Sarah H. Lisanby, Angel V. Peterchev
    Abstract:

    Electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) are conventionally applied with a fixed stimulus current amplitude, which may result in differences in the neural stimulation strength and focality across patients due to interindividual Anatomical Variability. The objective of this study is to quantify the effect of head Anatomical Variability associated with age, sex, and individual differences on the induced electric field characteristics in ECT and MST. Six stimulation modalities were modeled including bilateral and right unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular, cap, and double-cone coils. The electric field was computed using the finite element method in a parameterized spherical head model representing the Variability in the general population. Head tissue layer thicknesses and conductivities were varied to examine the impact of interindividual Anatomical differences on the stimulation strength, depth, and focality. Skull conductivity most strongly affects the ECT electric field, whereas the MST electric field is independent of tissue conductivity variation in this model but is markedly affected by differences in head diameter. Focal ECT electrode configurations such as FEAST is more sensitive to Anatomical Variability than that of less focal paradigms such as BL ECT. In MST, Anatomical Variability has stronger influence on the electric field of the cap and circular coils compared to the double-cone coil, possibly due to the more superficial field of the former. The Variability of the ECT and MST electric fields due to Anatomical differences should be considered in the interpretation of existing studies and in efforts to improve dosing approaches for better control of stimulation strength and focality across patients, such as individualization of the current amplitude. The conventional approach to individualizing dosage by titrating the number of pulses cannot compensate for differences in the spatial extent of stimulation that result from Anatomical Variability.

  • electric field characteristics of electroconvulsive therapy with individualized current amplitude a preclinical study
    International Conference of the IEEE Engineering in Medicine and Biology Society, 2013
    Co-Authors: Won Lee, Sarah H. Lisanby, Andrew F Laine, Angel V. Peterchev
    Abstract:

    This study examines the characteristics of the electric field induced in the brain by electroconvulsive therapy (ECT) with individualized current amplitude. The electric field induced by bilateral (BL), bifrontal (BF), right unilateral (RUL), and frontomedial (FM) ECT electrode configurations was computed in Anatomically realistic finite element models of four nonhuman primates (NHPs). We generated maps of the electric field strength relative to an empirical neural activation threshold, and determined the stimulation strength and focality at fixed current amplitude and at individualized current amplitudes corresponding to seizure threshold (ST) measured in the anesthetized NHPs. The results show less variation in brain volume stimulated above threshold with individualized current amplitudes (16-36%) compared to fixed current amplitude (30-62%). Further, the stimulated brain volume at amplitude-titrated ST is substantially lower than that for ECT with conventional fixed current amplitudes. Thus individualizing the ECT stimulus current could compensate for individual Anatomical Variability and result in more focal and uniform electric field exposure across different subjects compared to the standard clinical practice of using high, fixed current for all patients.

  • effect of Anatomical Variability on neural stimulation strength and focality in electroconvulsive therapy ect and magnetic seizure therapy mst
    International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
    Co-Authors: Zhide Deng, Sarah H. Lisanby, Angel V. Peterchev
    Abstract:

    We present a quantitative comparison of two metrics-neural stimulation strength and focality-in electrocon-vulsive therapy (ECT) and magnetic seizure therapy (MST) using finite-element method (FEM) simulation in a spherical head model. Five stimulation modalities were modeled, including bilateral ECT, unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular and double-cone coils, with stimulation parameters identical to those applied in clinical practice. We further examine the effect on the stimulation metrics of individual-, sex- and age-related Variability in tissue layer thickness and conductivity. Neural stimulation by MST is shown to be more focal and superficial than ECT. This result suggests that it may be advantageous to reduce the current used in ECT. The stimulation strength in MST is also less sensitive to variations in head geometry and tissue conductivity than in ECT. Individualization of pulse amplitude in both ECT and MST could compensate for Anatomical Variability, which could lead to more consistent clinical outcomes.

  • effect of Anatomical Variability on neural stimulation strength and focality in electroconvulsive therapy ect and magnetic seizure therapy mst
    International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
    Co-Authors: Zhide Deng, Sarah H. Lisanby, Angel V. Peterchev
    Abstract:

    We present a quantitative comparison of two metrics-neural stimulation strength and focality-in electrocon-vulsive therapy (ECT) and magnetic seizure therapy (MST) using finite-element method (FEM) simulation in a spherical head model. Five stimulation modalities were modeled, including bilateral ECT, unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular and double-cone coils, with stimulation parameters identical to those applied in clinical practice. We further examine the effect on the stimulation metrics of individual-, sex- and age-related Variability in tissue layer thickness and conductivity. Neural stimulation by MST is shown to be more focal and superficial than ECT. This result suggests that it may be advantageous to reduce the current used in ECT. The stimulation strength in MST is also less sensitive to variations in head geometry and tissue conductivity than in ECT. Individualization of pulse amplitude in both ECT and MST could compensate for Anatomical Variability, which could lead to more consistent clinical outcomes.

Songlin Ding - One of the best experts on this subject based on the ideXlab platform.

  • multi template analysis of human perirhinal cortex in brain mri explicitly accounting for Anatomical Variability
    NeuroImage, 2017
    Co-Authors: Long Xie, John Pluta, Sandhitsu R Das, Laura E M Wisse, Hongzhi Wang, Lauren Mancuso, Dasha Kliot, Brian B Avants, Songlin Ding
    Abstract:

    Abstract Rational The human perirhinal cortex (PRC) plays critical roles in episodic and semantic memory and visual perception. The PRC consists of Brodmann areas 35 and 36 (BA35, BA36). In Alzheimer's disease (AD), BA35 is the first cortical site affected by neurofibrillary tangle pathology, which is closely linked to neural injury in AD. Large Anatomical Variability, manifested in the form of different cortical folding and branching patterns, makes it difficult to segment the PRC in MRI scans. Pathology studies have found that in ~97% of specimens, the PRC falls into one of three discrete Anatomical variants. However, current methods for PRC segmentation and morphometry in MRI are based on single-template approaches, which may not be able to accurately model these discrete variants Methods A multi-template analysis pipeline that explicitly accounts for Anatomical Variability is used to automatically label the PRC and measure its thickness in T2-weighted MRI scans. The pipeline uses multi-atlas segmentation to automatically label medial temporal lobe cortices including entorhinal cortex, PRC and the parahippocampal cortex. Pairwise registration between label maps and clustering based on residual dissimilarity after registration are used to construct separate templates for the Anatomical variants of the PRC. An optimal path of deformations linking these templates is used to establish correspondences between all the subjects. Experimental evaluation focuses on the ability of single-template and multi-template analyses to detect differences in the thickness of medial temporal lobe cortices between patients with amnestic mild cognitive impairment (aMCI, n=41) and age-matched controls (n=44). Results The proposed technique is able to generate templates that recover the three dominant discrete variants of PRC and establish more meaningful correspondences between subjects than a single-template approach. The largest reduction in thickness associated with aMCI, in absolute terms, was found in left BA35 using both regional and summary thickness measures. Further, statistical maps of regional thickness difference between aMCI and controls revealed different patterns for the three Anatomical variants.

Joo-heon Yoon - One of the best experts on this subject based on the ideXlab platform.

  • Notice of retraction: duplicate data reported in "Anatomical Variability of the maxillary artery: findings from 100 Asian cadaveric dissections" (Arch Otolaryngol Head Neck Surg. 2010;136[8]:813-818.).
    Archives of otolaryngology--head & neck surgery, 2012
    Co-Authors: Jin Kook Kim, Jae Hoon Cho, Yeo-jin Lee, Chang-hoon Kim, Jung Ho Bae, Jeung-gweon Lee, Joo-heon Yoon
    Abstract:

    W e are writing to retract the article “Anatomical Variability of the Maxillary Artery: Findings From 100 Asian Cadaveric Dissections,” which was published in the August 2010 issue of the Archives. The data reported in that article were generated by many persons, working in many different departments, and a number of articles were published based on these data. In preparing this most recent article, we were unaware that another article based on these data, written by some of our colleagues, reported substantial amounts of the same data as our article. Since our colleagues’ article was published 1 month before ours, we would like to retract our article. We regret any problems or confusion that the publication of our article, with its duplicate data, and our delay in reporting this to the Archives and its readers may have caused. Author Affiliations: Department of Otorhinolaryngology– Head and Neck Surgery, Konkuk University School of Medicine (Drs J.-K. Kim, Cho, and Y.-J. Lee), Department of Otorhinolaryngology (Drs C.-H. Kim, J.-G. Lee, and Yoon), Airway Mucus Institute (Drs C.-H. Kim and Yoon), Research Center for Human Natural Defense System (Dr Yoon), and BK21 Project for Medical Science (Dr Yoon), Yonsei University College of Medicine, and Department of Otorhinolaryngology, Ewha Womans University School of Medicine (Dr Bae), Seoul, Korea. Correspondence: Dr Yoon, Department of Otorhinolaryngology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, Korea (jhyoon@yuhs.ac). Financial Disclosure: None reported.

  • Anatomical Variability of the Maxillary Artery: Findings From 100 Asian Cadaveric Dissections
    Archives of otolaryngology--head & neck surgery, 2010
    Co-Authors: Jin Kook Kim, Jae Hoon Cho, Yeo-jin Lee, Chang-hoon Kim, Jung Ho Bae, Jeung-gweon Lee, Joo-heon Yoon
    Abstract:

    Objective To describe the Anatomical Variability of the maxillary artery. Design Anatomical study. Setting Academic institution. Subjects One hundred midsagittal sections of randomly selected adult cadaver heads with intact maxillary sinuses, pterygopalatine fossa, and surrounding structures. Main Outcome Measures The location of the proximal portion of the maxillary artery in relation to the lateral pterygoid muscle, the branches of the mandibular division of the trigeminal nerve, and the branching patterns of the third section of the maxillary artery. Results The first and second sections of the maxillary artery most commonly traveled through the lateral aspect of the lateral pterygoid muscle, with the inferior alveolar nerve, lingual nerve, and buccal nerve on the medial side of the maxillary artery (61.0%). The course and branching type of the third section of the maxillary artery were classified into 3 patterns: loop (61.0%), bifurcated (19.0%), and straight (18.0%). In most cases (62.0%), the division point of the maxillary artery was located on the superior and medial thirds of the posterior wall of the maxilla. Conclusion This study provides detailed information concerning the Anatomical Variability of the maxillary artery, which we hope will help prevent the arterial bleeding that may occur during mandibular or maxillary osteotomy or maxillectomy for ligation of the sphenopalatine artery.

Sarah H. Lisanby - One of the best experts on this subject based on the ideXlab platform.

  • electric field model of transcranial electric stimulation in nonhuman primates correspondence to individual motor threshold
    IEEE Transactions on Biomedical Engineering, 2015
    Co-Authors: Won Hee Lee, Sarah H. Lisanby, Andrew F Laine, Angel V. Peterchev
    Abstract:

    Objective: To develop a pipeline for realistic head models of nonhuman primates (NHPs) for simulations of noninvasive brain stimulation, and use these models together with empirical threshold measurements to demonstrate that the models capture individual Anatomical Variability. Methods: Based on structural MRI data, we created models of the electric field (E-field) induced by right unilateral (RUL) electroconvulsive therapy (ECT) in four rhesus macaques. Individual motor threshold (MT) was measured with transcranial electric stimulation (TES) administered through the RUL electrodes in the same subjects. Results: The interindividual Anatomical differences resulted in 57% variation in median E-field strength in the brain at fixed stimulus current amplitude. Individualization of the stimulus current by MT reduced the E-field variation in the target motor area by 27%. There was significant correlation between the measured MT and the ratio of simulated electrode current and E-field strength ( $r^{2} = 0.95$ , $p = 0.026$ ). Exploratory analysis revealed significant correlations of this ratio with Anatomical parameters including of the superior electrode-to-cortex distance, vertex-to-cortex distance, and brain volume ( $r^{2} > 0.96$ , $p ). The neural activation threshold was estimated to be $0.45 \pm 0.07$ V/cm for 0.2-ms stimulus pulse width. Conclusion: These results suggest that our individual-specific NHP E-field models appropriately capture individual Anatomical Variability relevant to the dosing of TES/ECT. These findings are exploratory due to the small number of subjects. Significance: This study can contribute insight in NHP studies of ECT and other brain stimulation interventions, help link the results to clinical studies, and ultimately lead to more rational brain stimulation dosing paradigms.

  • Effect of Anatomical Variability on Electric Field Characteristics of Electroconvulsive Therapy and Magnetic Seizure Therapy: A Parametric Modeling Study
    IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society, 2014
    Co-Authors: Zhide Deng, Sarah H. Lisanby, Angel V. Peterchev
    Abstract:

    Electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) are conventionally applied with a fixed stimulus current amplitude, which may result in differences in the neural stimulation strength and focality across patients due to interindividual Anatomical Variability. The objective of this study is to quantify the effect of head Anatomical Variability associated with age, sex, and individual differences on the induced electric field characteristics in ECT and MST. Six stimulation modalities were modeled including bilateral and right unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular, cap, and double-cone coils. The electric field was computed using the finite element method in a parameterized spherical head model representing the Variability in the general population. Head tissue layer thicknesses and conductivities were varied to examine the impact of interindividual Anatomical differences on the stimulation strength, depth, and focality. Skull conductivity most strongly affects the ECT electric field, whereas the MST electric field is independent of tissue conductivity variation in this model but is markedly affected by differences in head diameter. Focal ECT electrode configurations such as FEAST is more sensitive to Anatomical Variability than that of less focal paradigms such as BL ECT. In MST, Anatomical Variability has stronger influence on the electric field of the cap and circular coils compared to the double-cone coil, possibly due to the more superficial field of the former. The Variability of the ECT and MST electric fields due to Anatomical differences should be considered in the interpretation of existing studies and in efforts to improve dosing approaches for better control of stimulation strength and focality across patients, such as individualization of the current amplitude. The conventional approach to individualizing dosage by titrating the number of pulses cannot compensate for differences in the spatial extent of stimulation that result from Anatomical Variability.

  • electric field characteristics of electroconvulsive therapy with individualized current amplitude a preclinical study
    International Conference of the IEEE Engineering in Medicine and Biology Society, 2013
    Co-Authors: Won Lee, Sarah H. Lisanby, Andrew F Laine, Angel V. Peterchev
    Abstract:

    This study examines the characteristics of the electric field induced in the brain by electroconvulsive therapy (ECT) with individualized current amplitude. The electric field induced by bilateral (BL), bifrontal (BF), right unilateral (RUL), and frontomedial (FM) ECT electrode configurations was computed in Anatomically realistic finite element models of four nonhuman primates (NHPs). We generated maps of the electric field strength relative to an empirical neural activation threshold, and determined the stimulation strength and focality at fixed current amplitude and at individualized current amplitudes corresponding to seizure threshold (ST) measured in the anesthetized NHPs. The results show less variation in brain volume stimulated above threshold with individualized current amplitudes (16-36%) compared to fixed current amplitude (30-62%). Further, the stimulated brain volume at amplitude-titrated ST is substantially lower than that for ECT with conventional fixed current amplitudes. Thus individualizing the ECT stimulus current could compensate for individual Anatomical Variability and result in more focal and uniform electric field exposure across different subjects compared to the standard clinical practice of using high, fixed current for all patients.

  • effect of Anatomical Variability on neural stimulation strength and focality in electroconvulsive therapy ect and magnetic seizure therapy mst
    International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
    Co-Authors: Zhide Deng, Sarah H. Lisanby, Angel V. Peterchev
    Abstract:

    We present a quantitative comparison of two metrics-neural stimulation strength and focality-in electrocon-vulsive therapy (ECT) and magnetic seizure therapy (MST) using finite-element method (FEM) simulation in a spherical head model. Five stimulation modalities were modeled, including bilateral ECT, unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular and double-cone coils, with stimulation parameters identical to those applied in clinical practice. We further examine the effect on the stimulation metrics of individual-, sex- and age-related Variability in tissue layer thickness and conductivity. Neural stimulation by MST is shown to be more focal and superficial than ECT. This result suggests that it may be advantageous to reduce the current used in ECT. The stimulation strength in MST is also less sensitive to variations in head geometry and tissue conductivity than in ECT. Individualization of pulse amplitude in both ECT and MST could compensate for Anatomical Variability, which could lead to more consistent clinical outcomes.

  • effect of Anatomical Variability on neural stimulation strength and focality in electroconvulsive therapy ect and magnetic seizure therapy mst
    International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
    Co-Authors: Zhide Deng, Sarah H. Lisanby, Angel V. Peterchev
    Abstract:

    We present a quantitative comparison of two metrics-neural stimulation strength and focality-in electrocon-vulsive therapy (ECT) and magnetic seizure therapy (MST) using finite-element method (FEM) simulation in a spherical head model. Five stimulation modalities were modeled, including bilateral ECT, unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular and double-cone coils, with stimulation parameters identical to those applied in clinical practice. We further examine the effect on the stimulation metrics of individual-, sex- and age-related Variability in tissue layer thickness and conductivity. Neural stimulation by MST is shown to be more focal and superficial than ECT. This result suggests that it may be advantageous to reduce the current used in ECT. The stimulation strength in MST is also less sensitive to variations in head geometry and tissue conductivity than in ECT. Individualization of pulse amplitude in both ECT and MST could compensate for Anatomical Variability, which could lead to more consistent clinical outcomes.

Jin Kook Kim - One of the best experts on this subject based on the ideXlab platform.

  • Notice of retraction: duplicate data reported in "Anatomical Variability of the maxillary artery: findings from 100 Asian cadaveric dissections" (Arch Otolaryngol Head Neck Surg. 2010;136[8]:813-818.).
    Archives of otolaryngology--head & neck surgery, 2012
    Co-Authors: Jin Kook Kim, Jae Hoon Cho, Yeo-jin Lee, Chang-hoon Kim, Jung Ho Bae, Jeung-gweon Lee, Joo-heon Yoon
    Abstract:

    W e are writing to retract the article “Anatomical Variability of the Maxillary Artery: Findings From 100 Asian Cadaveric Dissections,” which was published in the August 2010 issue of the Archives. The data reported in that article were generated by many persons, working in many different departments, and a number of articles were published based on these data. In preparing this most recent article, we were unaware that another article based on these data, written by some of our colleagues, reported substantial amounts of the same data as our article. Since our colleagues’ article was published 1 month before ours, we would like to retract our article. We regret any problems or confusion that the publication of our article, with its duplicate data, and our delay in reporting this to the Archives and its readers may have caused. Author Affiliations: Department of Otorhinolaryngology– Head and Neck Surgery, Konkuk University School of Medicine (Drs J.-K. Kim, Cho, and Y.-J. Lee), Department of Otorhinolaryngology (Drs C.-H. Kim, J.-G. Lee, and Yoon), Airway Mucus Institute (Drs C.-H. Kim and Yoon), Research Center for Human Natural Defense System (Dr Yoon), and BK21 Project for Medical Science (Dr Yoon), Yonsei University College of Medicine, and Department of Otorhinolaryngology, Ewha Womans University School of Medicine (Dr Bae), Seoul, Korea. Correspondence: Dr Yoon, Department of Otorhinolaryngology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, Korea (jhyoon@yuhs.ac). Financial Disclosure: None reported.

  • Anatomical Variability of the Maxillary Artery: Findings From 100 Asian Cadaveric Dissections
    Archives of otolaryngology--head & neck surgery, 2010
    Co-Authors: Jin Kook Kim, Jae Hoon Cho, Yeo-jin Lee, Chang-hoon Kim, Jung Ho Bae, Jeung-gweon Lee, Joo-heon Yoon
    Abstract:

    Objective To describe the Anatomical Variability of the maxillary artery. Design Anatomical study. Setting Academic institution. Subjects One hundred midsagittal sections of randomly selected adult cadaver heads with intact maxillary sinuses, pterygopalatine fossa, and surrounding structures. Main Outcome Measures The location of the proximal portion of the maxillary artery in relation to the lateral pterygoid muscle, the branches of the mandibular division of the trigeminal nerve, and the branching patterns of the third section of the maxillary artery. Results The first and second sections of the maxillary artery most commonly traveled through the lateral aspect of the lateral pterygoid muscle, with the inferior alveolar nerve, lingual nerve, and buccal nerve on the medial side of the maxillary artery (61.0%). The course and branching type of the third section of the maxillary artery were classified into 3 patterns: loop (61.0%), bifurcated (19.0%), and straight (18.0%). In most cases (62.0%), the division point of the maxillary artery was located on the superior and medial thirds of the posterior wall of the maxilla. Conclusion This study provides detailed information concerning the Anatomical Variability of the maxillary artery, which we hope will help prevent the arterial bleeding that may occur during mandibular or maxillary osteotomy or maxillectomy for ligation of the sphenopalatine artery.