RF-related heating assessment of extracranial neurosurgical implants at 7T

Sammet, Christina L.; Yang, Xiangyu; Wassenaar, Peter A.; Bourekas, Eric C.; Yuh, Brian A.; Shellock, Frank G.; Sammet, Steffen; Knopp, Michael V.

doi:10.1016/j.mri.2012.10.025

Cited by 35 publications

(42 citation statements)

References 15 publications

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“…1e). The physical phantom was filled to a depth of 90 mm with a 2.5 g/L saline solution with a conductivity σ = 0.47 S/m at room temperature [40,41]. The conductivity was measured with the YSI model 30 conductivity meter (YSI Incorporated, Yellow Springs, Ohio 45387 USA).…”

Section: Methodsmentioning

confidence: 99%

Assessing the Electromagnetic Fields Generated By a Radiofrequency MRI Body Coil at 64 MHz: Defeaturing Versus Accuracy

Lucano

Liberti

Mendoza

et al. 2016

IEEE Trans. Biomed. Eng.

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Goal-This study aims at a systematic assessment of five computational models of a birdcage coil for magnetic resonance imaging (MRI) with respect to accuracy and computational cost.Methods-The models were implemented using the same geometrical model and numerical algorithm, but different driving methods (i.e., coil "defeaturing"). The defeatured models were labeled as: specific (S2), generic (G32, G16), and hybrid (H16, H16 fr-forced ). The accuracy of the models was evaluated using the "Symmetric Mean Absolute Percentage Error" ("SMAPE"), by comparison with measurements in terms of frequency response, as well as electric (||E ⃗ ||) and magnetic (||B ⃗ ||) field magnitude. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptResults-All the models computed the ||B ⃗ || within 35 % of the measurements, only the S2, G32, and H16 were able to accurately model the ||E ⃗ || inside the phantom with a maximum SMAPE of 16 %. Outside the phantom, only the S2 showed a SMAPE lower than 11 %. Conclusions-Resultsshowed that assessing the accuracy of ||B ⃗ || based only on comparison along the central longitudinal line of the coil can be misleading. Generic or hybrid coils -when properly modeling the currents along the rings/rungs -were sufficient to accurately reproduce the fields inside a phantom while a specific model was needed to accurately model ||E ⃗ || in the space between coil and phantom.Significance-Computational modeling of birdcage body coils is extensively used in the evaluation of RF-induced heating during MRI. Experimental validation of numerical models is needed to determine if a model is an accurate representation of a physical coil.

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Section: Methodsmentioning

confidence: 99%

Assessing the Electromagnetic Fields Generated By a Radiofrequency MRI Body Coil at 64 MHz: Defeaturing Versus Accuracy

Lucano

Liberti

Mendoza

et al. 2016

IEEE Trans. Biomed. Eng.

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“…Besides these studies, other published articles describe safety studies of aneurysm clips [59], implants for earnose-throat surgery [60], upper eye implants [61], cranial fixation plates [62], an EEG-cap [63], intraocular lenses [64], actuators [65], ballistic objects [66], and extracranial neurosurgical implants [67].…”

Section: Safety Of Implantsmentioning

confidence: 99%

Safety of Ultra-High Field MRI: What are the Specific Risks?

Osch

Webb

2014

Curr Radiol Rep

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There are currently more than 50 ultra-high field (7 T and above) MRI systems installed around the world. The vast majority of these perform studies on humans, whether healthy volunteers, volunteers for clinical research, or actual patients. The increased magnetic field strength potentially raises new safety concerns in the areas of the effects of the static magnetic field itself, increased power deposition due to the higher operating frequency, and acoustic noise. There are currently very different operational modes in different institutions, with policies effectively set by local ethics committees. This article summarizes the current legal and practical status regarding safety of ultra-high field MRI.

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“…B 0 is orders of magnitudes larger than the magnetic field of the earth and can torque, attract and accelerate ferromagnetic objects in direction of the opening of the bore of an MRI scanner. B 0 can also interfere with implanted devices such as pumps and pace makers [18–26,1,27,28,2,29,30,15,31,12,16,32–47,7,48–62,11,63–73]. …”

Section: Magnetic Fields In An Mri Suitementioning

confidence: 99%

“…The 5 Gauss line of an MRI suite defines a border to an area in which the magnetic field could affect implanted devices such as pacemakers [7]. Special warning signs about the strong magnetic field and its associated hazards need to be set up in the MRI facility.…”

Section: Mri Zonesmentioning

confidence: 99%

“…Especially referring physicians who know details of a patient’s medical history can improve the MRI safety screening process when they are aware of the risks of an MRI scan by pre-screening their patients before an MRI exam [5]. This is particularly important in high-risk patients and in patients with new implants that have not yet been tested for MRI compatibility [6,7]. …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic resonance safety

Sammet

2016

Abdom Radiol

Self Cite

140

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Magnetic Resonance Imaging (MRI) has a superior soft-tissue contrast compared to other radiological imaging modalities and its physiological and functional applications have led to a significant increase in MRI scans worldwide. A comprehensive MRI safety training to protect patients and other healthcare workers from potential bio-effects and risks of the magnetic fields in an MRI suite is therefore essential. The knowledge of the purpose of safety zones in an MRI suite as well as MRI appropriateness criteria is important for all healthcare professionals who will work in the MRI environment or refer patients for MRI scans. The purpose of this article is to give an overview of current magnetic resonance safety guidelines and discuss the safety risks of magnetic fields in an MRI suite including forces and torque of ferromagnetic objects, tissue heating, peripheral nerve stimulation and hearing damages. MRI safety and compatibility of implanted devices, MRI scans during pregnancy and the potential risks of MRI contrast agents will also be discussed and a comprehensive MRI safety training to avoid fatal accidents in an MRI suite will be presented.

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RF-related heating assessment of extracranial neurosurgical implants at 7T

Cited by 35 publications

References 15 publications

Assessing the Electromagnetic Fields Generated By a Radiofrequency MRI Body Coil at 64 MHz: Defeaturing Versus Accuracy

Assessing the Electromagnetic Fields Generated By a Radiofrequency MRI Body Coil at 64 MHz: Defeaturing Versus Accuracy

Safety of Ultra-High Field MRI: What are the Specific Risks?

Magnetic resonance safety

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