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Jeong H, Ntolkeras G, Alhilani M, Atefi SR, Zöllei L, Fujimoto K, Pourvaziri A, Lev MH, Grant PE, Bonmassar G. Development, validation, and pilot MRI safety study of a high-resolution, open source, whole body pediatric numerical simulation model. PLoS One 2021; 16:e0241682. [PMID: 33439896 PMCID: PMC7806143 DOI: 10.1371/journal.pone.0241682] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
Numerical body models of children are used for designing medical devices, including but not limited to optical imaging, ultrasound, CT, EEG/MEG, and MRI. These models are used in many clinical and neuroscience research applications, such as radiation safety dosimetric studies and source localization. Although several such adult models have been reported, there are few reports of full-body pediatric models, and those described have several limitations. Some, for example, are either morphed from older children or do not have detailed segmentations. Here, we introduce a 29-month-old male whole-body native numerical model, "MARTIN", that includes 28 head and 86 body tissue compartments, segmented directly from the high spatial resolution MRI and CT images. An advanced auto-segmentation tool was used for the deep-brain structures, whereas 3D Slicer was used to segment the non-brain structures and to refine the segmentation for all of the tissue compartments. Our MARTIN model was developed and validated using three separate approaches, through an iterative process, as follows. First, the calculated volumes, weights, and dimensions of selected structures were adjusted and confirmed to be within 6% of the literature values for the 2-3-year-old age-range. Second, all structural segmentations were adjusted and confirmed by two experienced, sub-specialty certified neuro-radiologists, also through an interactive process. Third, an additional validation was performed with a Bloch simulator to create synthetic MR image from our MARTIN model and compare the image contrast of the resulting synthetic image with that of the original MRI data; this resulted in a "structural resemblance" index of 0.97. Finally, we used our model to perform pilot MRI safety simulations of an Active Implantable Medical Device (AIMD) using a commercially available software platform (Sim4Life), incorporating the latest International Standards Organization guidelines. This model will be made available on the Athinoula A. Martinos Center for Biomedical Imaging website.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Georgios Ntolkeras
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michel Alhilani
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Medicine, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Seyed Reza Atefi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Lilla Zöllei
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Kyoko Fujimoto
- Center for Devices and Radiological Health, U. S. Food and Drug Administration, Silver Spring, MD, United States of America
| | - Ali Pourvaziri
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michael H. Lev
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - P. Ellen Grant
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
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2
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Sayed D, Chakravarthy K, Amirdelfan K, Kalia H, Meacham K, Shirvalkar P, Falowski S, Petersen E, Hagedorn JM, Pope J, Leever J, Deer T. A Comprehensive Practice Guideline for Magnetic Resonance Imaging Compatibility in Implanted Neuromodulation Devices. Neuromodulation 2020; 23:893-911. [PMID: 32809275 DOI: 10.1111/ner.13233] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 06/06/2020] [Accepted: 06/16/2020] [Indexed: 12/12/2022]
Abstract
OBJECTIVES The evolution of neuromodulation devices in order to enter magnetic resonance imaging (MRI) scanners has been one of understanding limitations, engineering modifications, and the development of a consensus within the community in which the FDA could safely administer labeling for the devices. In the initial decades of neuromodulation, it has been contraindicated for MRI use with implanted devices. In this review, we take a comprehensive approach to address all the major products currently on the market in order to provide physicians with the ability to determine when an MRI can be performed for each type of device implant. MATERIALS AND METHODS We have prepared a narrative review of MRI guidelines for currently marketed implanted neuromodulation devices including spinal cord stimulators, intrathecal drug delivery systems, peripheral nerve stimulators, deep brain stimulators, vagal nerve stimulators, and sacral nerve stimulators. Data sources included relevant literature identified through searches of PubMed, MEDLINE/OVID, SCOPUS, and manual searches of the bibliographies of known primary and review articles, as well as manufacturer-provided information. RESULTS Guidelines and recommendations for each device and their respective guidelines for use in and around MR environments are presented. CONCLUSIONS This is the first comprehensive guideline with regards to various devices in the market and MRI compatibility from the American Society of Pain and Neuroscience.
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Affiliation(s)
- Dawood Sayed
- University of Kansas Medical Center, Kansas City, KS, USA
| | - Krishnan Chakravarthy
- University of California San Diego, San Diego, CA, USA.,VA San Diego Healthcare, San Diego, CA, USA
| | - Kasra Amirdelfan
- Director of Medical Research, IPM Medical Group, Inc., Walnut Creek, CA, USA
| | - Hemant Kalia
- Rochester Regional Health System, Rochester, NY, USA.,Department of Physical Medicine & Rehabilitation, University of Rochester, NY, USA
| | - Kathleen Meacham
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Prasad Shirvalkar
- Anesthesiology (Pain Management) and Neurology, University of California San Francisco, San Francisco, CA, USA.,Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Steven Falowski
- Director of Functional Neurosurgery, Neurosurgical Associates of Lancaster, Lancaster, PA, USA
| | - Erika Petersen
- Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jonathan M Hagedorn
- Department of Anesthesiology and Perioperative Medicine, Division of Pain Medicine, Mayo Clinic, Rochester, MN, USA
| | - Jason Pope
- Evolve Restorative Center, Santa Rosa, CA, USA
| | - John Leever
- Radiology and Neurology and Neuroradiology Fellowship Program Director, Kansas University Medical Center, Kansas City, KS, USA
| | | | - Timothy Deer
- The Spine and Nerve Center of The Virginias, Charleston, WV, USA.,Anesthesiology and Pain Medicine, WVU School of Medicine, Morgantown, WV, USA
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Jabehdar Maralani P, Schieda N, Hecht EM, Litt H, Hindman N, Heyn C, Davenport MS, Zaharchuk G, Hess CP, Weinreb J. MRI safety and devices: An update and expert consensus. J Magn Reson Imaging 2019; 51:657-674. [PMID: 31566852 DOI: 10.1002/jmri.26909] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/22/2022] Open
Abstract
The use of magnetic resonance imaging (MRI) is increasing globally, and MRI safety issues regarding medical devices, which are constantly being developed or upgraded, represent an ongoing challenge for MRI personnel. To assist the MRI community, a panel of 10 radiologists with expertise in MRI safety from nine high-volume academic centers formed, with the objective of providing clarity on some of the MRI safety issues for the 10 most frequently questioned devices. Ten device categories were identified. The panel reviewed the literature, including key MRI safety issues regarding screening and adverse event reports, in addition to the manufacturer's Instructions For Use. Using a Delphi-inspired method, 36 practical recommendations were generated with 100% consensus that can aid the clinical MRI community. Level of Evidence: 5 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:657-674.
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Affiliation(s)
| | - Nicola Schieda
- Department of Radiology, University of Ottawa, Ottawa, Canada
| | - Elizabeth M Hecht
- Department of Radiology, Columbia University, New York, New York, USA
| | - Harold Litt
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nicole Hindman
- Department of Radiology, New York University, New York, New York, USA
| | - Chinthaka Heyn
- Department of Medical Imaging, University of Toronto, Toronto, Canada
| | | | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Christopher P Hess
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
| | - Jeffrey Weinreb
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut, USA
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5
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Favazza CP, Edmonson HA, Ma C, Shu Y, Felmlee JP, Watson RE, Gorny KR. Evaluation of feasibility of 1.5 Tesla prostate MRI using body coil RF transmit in a patient with an implanted vagus nerve stimulator. Med Phys 2017; 44:5749-5754. [PMID: 28880381 DOI: 10.1002/mp.12567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 06/29/2017] [Accepted: 08/23/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To assess risks of RF-heating of a vagus nerve stimulator (VNS) during 1.5 T prostate MRI using body coil transmit and to compare these risks with those associated with MRI head exams using a transmit/receive head coil. METHODS Spatial distributions of radio-frequency (RF) B1 fields generated by transmit/receive (T/R) body and head coils were empirically assessed along the long axis of a 1.5 T MRI scanner bore. Measurements were obtained along the center axis of the scanner and laterally offset by 15 cm (body coil) and 7 cm (head coil). RF-field measurements were supplemented with direct measurements of RF-heating of 15 cm long copper wires affixed to and submerged in the "neck" region of the gelled saline-filled (sodium chloride and polyacrylic acid) "head-and-torso" phantom. Temperature elevations at the lead tips were measured using fiber-optic thermometers with the phantom positioned at systematically increased distances from the scanner isocenter. RESULTS B1 field measurements demonstrated greater than 10 dB reduction in RF power at distances beyond 28 cm and 24 cm from isocenter for body and head coil, respectively. Moreover, RF power from body coil transmit at distances greater than 32 cm from isocenter was found to be lower than from the RF power from head coil transmit measured at locations adjacent to the coil array at its opening. Correspondingly, maximum temperature elevations at the tips of the copper wires decreased with increasing distance from isocenter - from 7.4°C at 0 cm to no appreciable heating at locations beyond 40 cm. CONCLUSIONS For the particular scanner model evaluated in this study, positioning an implanted VNS farther than 32 cm from isocenter (configuration achievable for prostate exams) can reduce risks of RF-heating resulting from the body coil transmit to those associated with using a T/R head coil.
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Affiliation(s)
| | | | - Chi Ma
- Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Yunhong Shu
- Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Joel P Felmlee
- Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Robert E Watson
- Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA
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6
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Fantaneanu TA, Tillman G, Garcia E, Grady T, Dworetzky BA. Preserved vagus nerve stimulator function after radiation therapy. Acta Neurol Scand 2017; 135:142-144. [PMID: 26968442 DOI: 10.1111/ane.12584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2016] [Indexed: 11/27/2022]
Abstract
BACKGROUND Epilepsy and breast cancer are both prevalent conditions. A subset of women with medically refractory epilepsy and vagus nerve stimulators (VNS) may later develop breast cancer and may require adjuvant radiation as part of their treatment regimen. However, to date, little data are available on the effects of radiation on VNS function. CASE PRESENTATION We present a young woman with tuberous sclerosis, developmental delay, and medically refractory epilepsy who developed left-sided breast cancer. Her epilepsy became controlled with a recent addition of a VNS implanted in her left chest wall. She required adjuvant radiation therapy to her left breast, and this raised the novel question of the safety of radiation on the integrity and functioning of the device, which we explore in this article. CONCLUSION This case is the first report of a patient with VNS for epilepsy and breast cancer who received radiation therapy proximal to the device. The device continued to function properly despite the exposure.
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Affiliation(s)
- T. A. Fantaneanu
- Department of Neurology; Brigham and Women's Hospital; Boston MA USA
| | - G. Tillman
- Department of Radiation Oncology; Massachusetts General Hospital; Boston MA USA
| | - E. Garcia
- Department of Neurology; Newton-Wellesley Hospital; Newton MA USA
| | - T. Grady
- Department of Surgery; Newton-Wellesley Hospital; Newton MA USA
| | - B. A. Dworetzky
- Department of Neurology; Brigham and Women's Hospital; Boston MA USA
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7
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Thornton JS. Technical challenges and safety of magnetic resonance imaging with in situ neuromodulation from spine to brain. Eur J Paediatr Neurol 2017; 21:232-241. [PMID: 27430172 DOI: 10.1016/j.ejpn.2016.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/13/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE This review summarises the need for MRI with in situ neuromodulation, the key safety challenges and how they may be mitigated, and surveys the current status of MRI safety for the main categories of neuro-stimulation device, including deep brain stimulation, vagus nerve stimulation, sacral neuromodulation, spinal cord stimulation systems, and cochlear implants. REVIEW SUMMARY When neuro-stimulator systems are introduced into the MRI environment a number of hazards arise with potential for patient harm, in particular the risk of thermal injury due to MRI-induced heating. For many devices however, safe MRI conditions can be determined, and MRI safely performed, albeit with possible compromise in anatomical coverage, image quality or extended acquisition time. CONCLUSIONS The increasing availability of devices conditional for 3 T MRI, whole-body transmit imaging, and imaging in the on-stimulation condition, will be of significant benefit to the growing population of patients benefitting from neuromodulation therapy, and open up new opportunities for functional imaging research.
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Affiliation(s)
- John S Thornton
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, Queen Square, London, UK; Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College London, London, UK.
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8
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Nagae LM, Lall N, Dahmoush H, Nyberg E, Mirsky D, Drees C, Honce JM. Diagnostic, treatment, and surgical imaging in epilepsy. Clin Imaging 2016; 40:624-36. [DOI: 10.1016/j.clinimag.2016.02.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/03/2016] [Accepted: 02/11/2016] [Indexed: 10/22/2022]
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9
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3T-MRI in patients with pharmacoresistant epilepsy and a vagus nerve stimulator: A pilot study. Epilepsy Res 2015; 110:62-70. [DOI: 10.1016/j.eplepsyres.2014.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/25/2014] [Accepted: 11/11/2014] [Indexed: 12/30/2022]
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10
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Favazza CP, King DM, Edmonson HA, Felmlee JP, Rossman PJ, Hangiandreou NJ, Watson RE, Gorny KR. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation. MEDICAL DEVICES-EVIDENCE AND RESEARCH 2014; 7:363-70. [PMID: 25378957 PMCID: PMC4219642 DOI: 10.2147/mder.s68657] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Radiofrequency (RF) shields have been recently developed for the purpose of shielding portions of the patient’s body during magnetic resonance imaging (MRI) examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (∼1 dB) of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices.
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Affiliation(s)
| | - Deirdre M King
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Joel P Felmlee
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
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11
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de Jonge JC, Melis GI, Gebbink TA, de Kort GAP, Leijten FSS. Safety of a dedicated brain MRI protocol in patients with a vagus nerve stimulator. Epilepsia 2014; 55:e112-5. [DOI: 10.1111/epi.12774] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Jeroen C. de Jonge
- Department of Neurology and Neurosurgery; Brain Center Rudolf Magnus; University Medical Center Utrecht; Utrecht The Netherlands
| | - Gerrit I. Melis
- Department of Radiology; University Medical Center Utrecht; Utrecht The Netherlands
| | - Tineke A. Gebbink
- Department of Neurology and Neurosurgery; Brain Center Rudolf Magnus; University Medical Center Utrecht; Utrecht The Netherlands
| | - Gérard A. P. de Kort
- Department of Radiology; University Medical Center Utrecht; Utrecht The Netherlands
| | - Frans S. S. Leijten
- Department of Neurology and Neurosurgery; Brain Center Rudolf Magnus; University Medical Center Utrecht; Utrecht The Netherlands
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12
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Abstract
The vagus nerve is a major component of the autonomic nervous system, has an important role in the regulation of metabolic homeostasis, and plays a key role in the neuroendocrine-immune axis to maintain homeostasis through its afferent and efferent pathways. Vagus nerve stimulation (VNS) refers to any technique that stimulates the vagus nerve, including manual or electrical stimulation. Left cervical VNS is an approved therapy for refractory epilepsy and for treatment resistant depression. Right cervical VNS is effective for treating heart failure in preclinical studies and a phase II clinical trial. The effectiveness of various forms of non-invasive transcutaneous VNS for epilepsy, depression, primary headaches, and other conditions has not been investigated beyond small pilot studies. The relationship between depression, inflammation, metabolic syndrome, and heart disease might be mediated by the vagus nerve. VNS deserves further study for its potentially favorable effects on cardiovascular, cerebrovascular, metabolic, and other physiological biomarkers associated with depression morbidity and mortality.
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13
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García-Navarrete E, Torres CV, Gallego I, Navas M, Pastor J, Sola R. Response to “Vagus nerve stimulation: Urgent need for the critical reappraisal of clinical effectiveness”. Seizure 2013; 22:490-1. [DOI: 10.1016/j.seizure.2013.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Revised: 03/19/2013] [Accepted: 03/20/2013] [Indexed: 11/30/2022] Open
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Shi C, Flanagan SR, Samadani U. Vagus nerve stimulation to augment recovery from severe traumatic brain injury impeding consciousness: a prospective pilot clinical trial. Neurol Res 2013; 35:263-76. [PMID: 23485054 PMCID: PMC4568744 DOI: 10.1179/1743132813y.0000000167] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES Traumatic brain injury (TBI) has high morbidity and mortality in both civilian and military populations. Blast and other mechanisms of TBI damage the brain by causing neurons to disconnect and atrophy. Such traumatic axonal injury can lead to persistent vegetative and minimally conscious states (VS and MCS), for which limited treatment options exist, including physical, occupational, speech, and cognitive therapies. More than 60 000 patients have received vagus nerve stimulation (VNS) for epilepsy and depression. In addition to decreased seizure frequency and severity, patients report enhanced mood, reduced daytime sleepiness independent of seizure control, increased slow wave sleep, and improved cognition, memory, and quality of life. Early stimulation of the vagus nerve accelerates the rate and extent of behavioral and cognitive recovery after fluid percussion brain injury in rats. METHODS We recently obtained Food and Drug Administration (FDA) approval for a pilot prospective randomized crossover trial to demonstrate objective improvement in clinical outcome by placement of a vagus nerve stimulator in patients who are recovering from severe TBI. Our hypothesis is that stimulation of the vagus nerve results in increased cerebral blood flow and metabolism in the forebrain, thalamus, and reticular formation, which promotes arousal and improved consciousness, thereby improving outcome after TBI resulting in MCS or VS. DISCUSSION If this study demonstrates that VNS can safely and positively impact outcome, then a larger randomized prospective crossover trial will be proposed.
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Affiliation(s)
- Chen Shi
- Department of Neurosurgery, New York University School of Medicine and NYU Langone Medical Center, 550 First Ave. New York, NY 10016
| | - Steven R. Flanagan
- Department of Rehabilitation Medicine, New York University School of Medicine and NYU Langone Medical Center, 240 E. 38 St. New York, NY 10016
| | - Uzma Samadani
- Department of Neurosurgery, New York University School of Medicine and NYU Langone Medical Center, 550 First Ave. New York, NY 10016
- Division of Neurosurgery, New York Harbor Healthcare System Manhattan Veterans Hospital, 423 E. 23 St. New York, NY 10010
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Abstract
Therapeutic devices provide new options for treating drug-resistant epilepsy. These devices act by a variety of mechanisms to modulate neuronal activity. Only vagus nerve stimulation (VNS), which continues to develop new technology, is approved for use in the United States. Deep brain stimulation of anterior thalamus for partial epilepsy recently was approved in Europe and several other countries. Responsive neurostimulation, which delivers stimuli to 1 or 2 seizure foci in response to a detected seizure, recently completed a successful multicenter trial. Several other trials of brain stimulation are in planning or underway. Transcutaneous magnetic stimulation (TMS) may provide a noninvasive method to stimulate cortex. Controlled studies of TMS are split on efficacy, which may depend on whether a seizure focus is near a possible region for stimulation. Seizure detection devices in the form of shake detectors via portable accelerometers can provide notification of an ongoing tonic-clonic seizure, or peace of mind in the absence of notification. Prediction of seizures from various aspects of electroencephalography (EEG) is in early stages. Prediction appears to be possible in a subpopulation of people with refractory seizures, and a clinical trial of an implantable prediction device is underway. Cooling of neocortex or hippocampus reversibly can attenuate epileptiform EEG activity and seizures, but engineering problems remain in its implementation. Optogenetics is a new technique that can control excitability of specific populations of neurons with light. Inhibition of epileptiform activity has been demonstrated in hippocampal slices, but use in humans will require more work. In general, devices provide useful palliation for otherwise uncontrollable seizures, but with a different risk profile than with most drugs. Optimizing the place of devices in therapy for epilepsy will require further development and clinical experience.
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Affiliation(s)
- Robert S Fisher
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, CA, USA.
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Dahmoush HM, Vossough A, Roberts TPL. Pediatric high-field magnetic resonance imaging. Neuroimaging Clin N Am 2012; 22:297-313, xi. [PMID: 22548934 DOI: 10.1016/j.nic.2012.02.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High-field 3 T magnetic resonance (MR) imaging provides greater signal-to-noise ratio (SNR) compared with 1.5 T systems. Various MR imaging clinical applications in children can benefit from improvements resulting from this increased SNR. High-resolution imaging of the brain, arterial spin labeling perfusion imaging, diffusion imaging, MR spectroscopy, and imaging of small anatomic parts are some areas in which these improvements can increase our clinical diagnostic capabilities. However, challenges inherent to 3 T imaging become more relevant in children. The use of 3 T imaging in children has allowed better diagnostic efficacy in neuroimaging, but certain technique modifications may be required for optimal imaging.
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Affiliation(s)
- Hisham M Dahmoush
- Neuroradiology Section, Department of Radiology, Children's Hospital of Philadelphia, Wood 2115, 324 South 34th Street, Philadelphia, PA 19104, USA
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Pang Y, Vigneron DB, Zhang X. Parallel traveling-wave MRI: a feasibility study. Magn Reson Med 2011; 67:965-78. [PMID: 21858863 DOI: 10.1002/mrm.23073] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 05/18/2011] [Accepted: 06/06/2011] [Indexed: 01/23/2023]
Abstract
Traveling-wave magnetic resonance imaging utilizes far fields of a single-piece patch antenna in the magnet bore to generate radio frequency fields for imaging large-size samples, such as the human body. In this work, the feasibility of applying the "traveling-wave" technique to parallel imaging is studied using microstrip patch antenna arrays with both the numerical analysis and experimental tests. A specific patch array model is built and each array element is a microstrip patch antenna. Bench tests show that decoupling between two adjacent elements is better than -26-dB while matching of each element reaches -36-dB, demonstrating excellent isolation performance and impedance match capability. The sensitivity patterns are simulated and g-factors are calculated for both unloaded and loaded cases. The results on B 1- sensitivity patterns and g-factors demonstrate the feasibility of the traveling-wave parallel imaging. Simulations also suggest that different array configuration such as patch shape, position and orientation leads to different sensitivity patterns and g-factor maps, which provides a way to manipulate B(1) fields and improve the parallel imaging performance. The proposed method is also validated by using 7T MR imaging experiments.
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Affiliation(s)
- Yong Pang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
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