Induced magnetic force in human heads exposed to 4 T MRI |
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Authors: | Ruiliang Wang PhD Gene‐Jack Wang MD Rita Z. Goldstein PhD Elisabeth C. Caparelli PhD Nora D. Volkow MD Joanna S. Fowler PhD Dardo Tomasi PhD |
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Affiliation: | 1. Medical Department, Brookhaven National Laboratory, Upton, New York, USA;2. SCAN Center, Stony Brook University, Stony Brook, New York, USA;3. National Institute on Alcoholism and Alcohol Abuse, Bethesda, Maryland, USA;4. National Institute on Drug Abuse, Bethesda, Maryland, USA |
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Abstract: | Purpose: To map the distribution of the magnetic force induced in the human head during magnetic resonance imaging (MRI) at 4 T for a large group of healthy volunteers. Materials and Methods: The magnetic field distribution in the head of 100 men and 18 women was mapped using phase mapping techniques. Statistical parametric mapping methods using a family‐wise error (FWE) corrected threshold P < 0.05 and region‐of‐interest analyses were used to assess the significance of the results. Results: Eyeballs, orbitofrontal and temporal cortices, subcallosal gyrus, anterior cingulate, midbrain, and brainstem (pons) are the brain regions most susceptible to magnetic force. The strength of the magnetic force density in the head was lower than 11.5 ± 5.3 N/m3 (right eyeball). The strength of the magnetic force density induced in occipital cortex varied linearly with the x‐rotation (pitch) angle. Conclusion: We found that the induced magnetic force is highly significant in the eyeballs, orbitofrontal and temporal cortices, subcallosal gyrus, anterior cingulate as well as midbrain and brainstem (pons), regardless of subjects' age or gender. The maximum induced magnetic force was 6 × 105 times weaker than the gravitational force; thus, biological effects of the magnetic force during imaging are not expected to be significant. J. Magn. Reson. Imaging 2010;31:815–820. ©2010 Wiley‐Liss, Inc. |
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Keywords: | magnetic resonance imaging magnetic gradient field induced magnetic force MRI safety phase mapping ROI analysis susceptibility‐weighted MR pulse sequence |
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