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Camera F, Merla C, De Santis V. Comparison of Transcranial Magnetic Stimulation Dosimetry between Structured and Unstructured Grids Using Different Solvers. Bioengineering (Basel) 2024; 11:712. [PMID: 39061794 DOI: 10.3390/bioengineering11070712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 07/05/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024] Open
Abstract
In recent years, the interest in transcranial magnetic stimulation (TMS) has surged, necessitating deeper understanding, development, and use of low-frequency (LF) numerical dosimetry for TMS studies. While various ad hoc dosimetric models exist, commercial software tools like SimNIBS v4.0 and Sim4Life v7.2.4 are preferred for their user-friendliness and versatility. SimNIBS utilizes unstructured tetrahedral mesh models, while Sim4Life employs voxel-based models on a structured grid, both evaluating induced electric fields using the finite element method (FEM) with different numerical solvers. Past studies primarily focused on uniform exposures and voxelized models, lacking realism. Our study compares these LF solvers across simplified and realistic anatomical models to assess their accuracy in evaluating induced electric fields. We examined three scenarios: a single-shell sphere, a sphere with an orthogonal slab, and a MRI-derived head model. The comparison revealed small discrepancies in induced electric fields, mainly in regions of low field intensity. Overall, the differences were contained (below 2% for spherical models and below 12% for the head model), showcasing the potential of computational tools in advancing exposure assessment required for TMS protocols in different bio-medical applications.
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Affiliation(s)
- Francesca Camera
- Division of Biotechnologies, Italian National Agency for Energy, New Technologies and Sustainable Economic Development (ENEA), 00123 Rome, Italy
| | - Caterina Merla
- Division of Biotechnologies, Italian National Agency for Energy, New Technologies and Sustainable Economic Development (ENEA), 00123 Rome, Italy
| | - Valerio De Santis
- Department of Industrial and Information Engineering and Economics, University of L'Aquila, 67100 L'Aquila, Italy
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Esmailzade Moghimi S, Mohammadi F, Yadegari F, Dehghan M, Hojjati SMM, Saadat P, Geraili Z, Alizadeh M. Verbal and oral apraxia in patients with acute stroke: Frequency, relationship, and some risk factors. APPLIED NEUROPSYCHOLOGY. ADULT 2024; 31:97-108. [PMID: 34726969 DOI: 10.1080/23279095.2021.1993225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Verbal and oral apraxia are two possible consequences of stroke. It seems that there are not sufficient studies regarding the frequency of these disorders. This study aimed to evaluate the frequency of Verbal and oral apraxia. In addition, the relationship between apraxia and some variables such as age, gender, and education, as well as the relationship between types of apraxia with each other, and damaged areas of the brain in apraxia of the oral system in Persian-speaking patients with stroke were studied. In this descriptive-analytical study, 42 patients participated using the convenient sampling method. Verbal and oral apraxia were assessed using the oral and verbal apraxia tasks for adults test. Data were analyzed using independent t-test, Chi-square, and Fisher's exact test. The frequency of patients with oral apraxia was 35.7%, those with verbal apraxia was 2.3%, and the combination of both verbal and oral apraxia was 4.7%. People with apraxia were significantly older than those without apraxia. There was not any significant relationship between apraxia and gender, apraxia and education, and oral apraxia with verbal apraxia (p < 0.05). The present study's findings showed the high frequency of post-stroke apraxia and the high rate of its incidence with age.
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Affiliation(s)
| | - Fatemeh Mohammadi
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran
| | - Fariba Yadegari
- Department of Speech Therapy, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mehdi Dehghan
- Mobility Impairment Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
- Department of Speech Therapy, School of Rehabilitation, Babol University of Medical Sciences, Babol, Iran
| | | | - Payam Saadat
- Mobility Impairment Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
- Department of Neurology, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Zahra Geraili
- Social Determinants of Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Maryam Alizadeh
- Mobility Impairment Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
- Department of Speech Therapy, School of Rehabilitation, Babol University of Medical Sciences, Babol, Iran
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Jeong H, Andersson J, Hess A, Jezzard P. Effect of subject-specific head morphometry on specific absorption rate estimates in parallel-transmit MRI at 7 T. Magn Reson Med 2023; 89:2376-2390. [PMID: 36656151 PMCID: PMC10952207 DOI: 10.1002/mrm.29589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 12/02/2022] [Accepted: 12/31/2022] [Indexed: 01/20/2023]
Abstract
PURPOSE To assess the accuracy of morphing an established reference electromagnetic head model to a subject-specific morphometry for the estimation of specific absorption rate (SAR) in 7T parallel-transmit (pTx) MRI. METHODS Synthetic T1 -weighted MR images were created from three high-resolution open-source electromagnetic head voxel models. The accuracy of morphing a "reference" (multimodal image-based detailed anatomical [MIDA]) electromagnetic model into a different subject's native space (Duke and Ella) was compared. Both linear and nonlinear registration methods were evaluated. Maximum 10-g averaged SAR was estimated for circularly polarized mode and for 5000 random RF shim sets in an eight-channel transmit head coil, and comparison made between the morphed MIDA electromagnetic models and the native Duke and Ella electromagnetic models, respectively. RESULTS The averaged error in maximum 10-g averaged SAR estimation across pTx MRI shim sets between the MIDA and the Duke target model was reduced from 17.5% with only rigid-body registration, to 11.8% when affine linear registration was used, and further reduced to 10.7% when nonlinear registration was used. The corresponding figures for the Ella model were 16.7%, 11.2%, and 10.1%. CONCLUSION We found that morphometry accounts for up to half of the subject-specific differences in pTx SAR. Both linear and nonlinear morphing of an electromagnetic model into a target subject improved SAR agreement by better matching head size, morphometry, and position. However, differences remained, likely arising from details in tissue composition estimation. Thus, the uncertainty of the head morphometry and tissue composition may need to be considered separately to achieve personalized SAR estimation.
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Affiliation(s)
- Hongbae Jeong
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
- Athinoula A. Martinos Center for Biomedical Imaging, Department of RadiologyMassachusetts General HospitalBostonMassachusettsUSA
| | - Jesper Andersson
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Aaron Hess
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
- Centre for Clinical Magnetic Resonance Research, Department of Cardiovascular MedicineUniversity of OxfordOxfordUK
- British Heart Foundation Centre for Research ExcellenceOxfordUK
| | - Peter Jezzard
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
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Non-invasive brain stimulation as therapeutic approach for ischemic stroke: Insights into the (sub)cellular mechanisms. Pharmacol Ther 2022; 235:108160. [PMID: 35183592 DOI: 10.1016/j.pharmthera.2022.108160] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 01/12/2023]
Abstract
Although spontaneous recovery can occur following ischemic stroke due to endogenous neuronal reorganization and neuroplastic events, the degree of functional improvement is highly variable, causing many patients to remain permanently impaired. In the last decades, non-invasive brain stimulation (NIBS) techniques have emerged as potential add-on interventions to the standard neurorehabilitation programs to improve post-stroke recovery. Due to their ability to modulate cortical excitability and to induce neuroreparative processes in the brain, multiple studies have assessed the safety, efficacy and (sub)cellular mechanisms of NIBS following ischemic stroke. In this review, an overview will be provided of the different NIBS techniques that are currently being investigated in (pre)clinical stroke studies. The NIBS therapies that will be discussed include transcranial magnetic stimulation, transcranial direct current stimulation and extremely low frequency electromagnetic stimulation. First, an overview will be given of the cellular mechanisms induced by NIBS that are associated with enhanced stroke outcome in preclinical models. Furthermore, the current knowledge on safety and efficacy of these NIBS techniques in stroke patients will be reviewed.
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Capone F, Salati S, Vincenzi F, Liberti M, Aicardi G, Apollonio F, Varani K, Cadossi R, Di Lazzaro V. Pulsed Electromagnetic Fields: A Novel Attractive Therapeutic Opportunity for Neuroprotection After Acute Cerebral Ischemia. Neuromodulation 2021; 25:1240-1247. [PMID: 34480781 DOI: 10.1111/ner.13489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/18/2021] [Accepted: 06/07/2021] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Acute cerebral ischemia is characterized by several pathological processes evolving during time, which contribute to the final tissue damage. Secondary processes, such as prolonged inflammatory response, impaired mitochondrial function and oxidative stress, are responsible for the progression of brain injury to the peri-infarct area, called "penumbra." Adenosine has been shown to play a crucial role in regulating the inflammatory cascade following brain ischemia. Pulsed electromagnetic fields (PEMFs) act as modulators of adenosine receptors, increasing the functionality of the endogenous adenosine. In particular, PEMF exposure induces a significant upregulation of A2A and A3 adenosine receptors in different neuronal cell types. Several lines of evidence suggest that PEMF exposure might play a neuroprotective role after ischemic damage. MATERIALS AND METHODS This review summarizes the current knowledge on the mechanism of action of PEMFs and their biological effects on neuronal damage both in preclinical and clinical studies. RESULTS PEMFs counteract hypoxia-induced apoptosis and ROS production in neuronal-like cells and exert a strong anti-inflammatory effect on microglial cells. Data from stroke animal models showed that PEMFs exposure is able to reduce the size of the infarct area and decrease the levels of pro-inflammatory mediators. In clinical studies, PEMFs stimulation proved to be safe and well tolerated. Preliminary results on acute ischemic stroke patients showed a dose-dependent reduction in the lesion size. CONCLUSIONS Altogether, these data demonstrate the efficacy of PEMFs against several mechanisms underlying ischemic damage and suggest that PEMFs might represent a novel noninvasive adjunctive treatment for acute ischemic stroke, providing neuroprotection and reducing functional deficits following ischemia.
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Affiliation(s)
- Fioravante Capone
- Unit of Neurology, Neurophysiology, and Neurobiology, Department of Medicine, Università Campus Bio-Medico, Roma, Italy
| | | | | | - Micaela Liberti
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome "La Sapienza", Roma, Italy
| | - Giorgio Aicardi
- Neurophysiology Research Unit, Department for Life Quality Studies, University of Bologna, Bologna, Italy
| | - Francesca Apollonio
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome "La Sapienza", Roma, Italy
| | - Katia Varani
- Department of Translational Medicine, University of Ferrara, Italy
| | | | - Vincenzo Di Lazzaro
- Unit of Neurology, Neurophysiology, and Neurobiology, Department of Medicine, Università Campus Bio-Medico, Roma, Italy
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Colella M, Paffi A, De Santis V, Apollonio F, Liberti M. Effect of skin conductivity on the electric field induced by transcranial stimulation techniques in different head models. Phys Med Biol 2021; 66:035010. [PMID: 33496268 DOI: 10.1088/1361-6560/abcde7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This study aims at quantifying the effect that using different skin conductivity values has on the estimation of the electric (E)-field distribution induced by transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in the brain of two anatomical models. The induced E-field was calculated with numerical simulations inside MIDA and Duke models, assigning to the skin a conductivity value estimated from a multi-layered skin model and three values taken from literature. The effect of skin conductivity variations on the local E-field induced by tDCS in the brain was up to 70%. In TMS, minor local differences, in the order of 20%, were obtained in regions of interest for the onset of possible side effects. Results suggested that an accurate model of the skin is necessary in all numerical studies that aim at precisely estimating the E-field induced during TMS and tDCS applications. This also highlights the importance of further experimental studies on human skin characterization, especially at low frequencies.
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Affiliation(s)
- Micol Colella
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| | - Alessandra Paffi
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| | - Valerio De Santis
- Department of Industrial and Information Engineering and Economics (DIIEE), University of L'Aquila, L'Aquila, Italy
| | - Francesca Apollonio
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| | - Micaela Liberti
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
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