| Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners. | |
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MedLine Citation:
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PMID: 20220368 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea. |
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Authors:
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James C Lin; Zhangwei Wang |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Health physics Volume: 98 ISSN: 1538-5159 ISO Abbreviation: Health Phys Publication Date: 2010 Apr |
Date Detail:
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Created Date: 2010-03-11 Completed Date: 2010-04-05 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 2985093R Medline TA: Health Phys Country: United States |
Other Details:
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Languages: eng Pagination: 603-13 Citation Subset: IM |
Affiliation:
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Department of Electrical and Computer Engineering, University of Illinois at Chicago, 851 S. Morgan Street (M/C 154), Chicago, IL 60607-7053, USA. lin@uic.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Absorption Acoustics* Electromagnetic Fields Equipment Safety / standards Head / anatomy & histology, radiation effects*, radiography Humans Magnetic Resonance Imaging / adverse effects*, instrumentation, methods*, standards Practice Guidelines as Topic Pressure Radiation Dosage Radiation Injuries* / prevention & control, radiography Radio Waves* Radiographic Image Interpretation, Computer-Assisted / instrumentation, methods*, standards United States United States Food and Drug Administration |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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