Radiofrequency safety of high permittivity pads in MRI—Impact of insulation material.
Saved in:
| Title: | Radiofrequency safety of high permittivity pads in MRI—Impact of insulation material. |
|---|---|
| Authors: | Brink, Wyger M.1,2 (AUTHOR) w.m.brink@utwente.nl, Remis, Rob F.3 (AUTHOR), Webb, Andrew G.1 (AUTHOR) |
| Source: | Magnetic Resonance in Medicine. May2023, Vol. 89 Issue 5, p2109-2116. 8p. |
| Subjects: | Insulating materials, Electric insulators & insulation, Permittivity, Radio frequency, Imaging phantoms |
| Abstract: | Purpose: High permittivity dielectric pads are known to be effective for tailoring the RF field and improving image quality in high field MRI. Despite a number of studies reporting benign specific absorption rate (SAR) effects, their "universal" safety remains an open concern. In this work, we evaluate the impact of the insulation material in between the pad and the body, using both RF simulations as well as phantom experiments. Methods: A 3T configuration with high permittivity material was simulated and characterized experimentally in terms of B1+ fields and RF power absorption, both with and without electrical insulation in between the high permittivity material and the sample. Different insulation conditions were compared, and electromagnetic analyses on the induced current density were performed to elucidate the effect. Results: Increases in RF heating of up to 49% were observed experimentally in a tissue‐mimicking phantom after removing the material insulation. The B1+ magnitude and RF transceive phase were not affected. Simulations indicated that an insulation thickness of 0.5–2 mm should be accounted for in numerical models in order to ensure reliable results. Conclusion: A reliable RF safety assessment of high permittivity dielectric pads requires accounting for the insulating properties of the plastic encasing. Ignoring the electrical insulation can lead to erroneous results with substantial increases in local SAR at the interface. Conversely, the material insulation does not need to be modeled to predict the B1+ effects during the design of the pad geometry. [ABSTRACT FROM AUTHOR] |
| Copyright of Magnetic Resonance in Medicine is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
|
Full text is not displayed to guests.
Login for full access.
|
|
| FullText | Links: – Type: pdflink Text: Availability: 1 |
|---|---|
| Header | DbId: egs DbLabel: Engineering Source An: 162165672 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
| IllustrationInfo | |
| Items | – Name: Title Label: Title Group: Ti Data: Radiofrequency safety of high permittivity pads in MRI—Impact of insulation material. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Brink%2C+Wyger+M%2E%22">Brink, Wyger M.</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> w.m.brink@utwente.nl</i><br /><searchLink fieldCode="AR" term="%22Remis%2C+Rob+F%2E%22">Remis, Rob F.</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Webb%2C+Andrew+G%2E%22">Webb, Andrew G.</searchLink><relatesTo>1</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Magnetic+Resonance+in+Medicine%22">Magnetic Resonance in Medicine</searchLink>. May2023, Vol. 89 Issue 5, p2109-2116. 8p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Insulating+materials%22">Insulating materials</searchLink><br /><searchLink fieldCode="DE" term="%22Electric+insulators+%26+insulation%22">Electric insulators & insulation</searchLink><br /><searchLink fieldCode="DE" term="%22Permittivity%22">Permittivity</searchLink><br /><searchLink fieldCode="DE" term="%22Radio+frequency%22">Radio frequency</searchLink><br /><searchLink fieldCode="DE" term="%22Imaging+phantoms%22">Imaging phantoms</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Purpose: High permittivity dielectric pads are known to be effective for tailoring the RF field and improving image quality in high field MRI. Despite a number of studies reporting benign specific absorption rate (SAR) effects, their "universal" safety remains an open concern. In this work, we evaluate the impact of the insulation material in between the pad and the body, using both RF simulations as well as phantom experiments. Methods: A 3T configuration with high permittivity material was simulated and characterized experimentally in terms of B1+ fields and RF power absorption, both with and without electrical insulation in between the high permittivity material and the sample. Different insulation conditions were compared, and electromagnetic analyses on the induced current density were performed to elucidate the effect. Results: Increases in RF heating of up to 49% were observed experimentally in a tissue‐mimicking phantom after removing the material insulation. The B1+ magnitude and RF transceive phase were not affected. Simulations indicated that an insulation thickness of 0.5–2 mm should be accounted for in numerical models in order to ensure reliable results. Conclusion: A reliable RF safety assessment of high permittivity dielectric pads requires accounting for the insulating properties of the plastic encasing. Ignoring the electrical insulation can lead to erroneous results with substantial increases in local SAR at the interface. Conversely, the material insulation does not need to be modeled to predict the B1+ effects during the design of the pad geometry. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Magnetic Resonance in Medicine is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=162165672 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1002/mrm.29580 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 8 StartPage: 2109 Subjects: – SubjectFull: Insulating materials Type: general – SubjectFull: Electric insulators & insulation Type: general – SubjectFull: Permittivity Type: general – SubjectFull: Radio frequency Type: general – SubjectFull: Imaging phantoms Type: general Titles: – TitleFull: Radiofrequency safety of high permittivity pads in MRI—Impact of insulation material. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Brink, Wyger M. – PersonEntity: Name: NameFull: Remis, Rob F. – PersonEntity: Name: NameFull: Webb, Andrew G. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: May2023 Type: published Y: 2023 Identifiers: – Type: issn-print Value: 07403194 Numbering: – Type: volume Value: 89 – Type: issue Value: 5 Titles: – TitleFull: Magnetic Resonance in Medicine Type: main |
| ResultId | 1 |
