Using Phase Difference Information to Detect Errors in the Flip Angle Measured with Actual Flip Angle Imaging at 7T
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- Matsuda Tsuyoshi
- Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University
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- Iwadate Yuji
- MR Applications and Workflow, GE Healthcare Japan Corporation
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- Mori Futoshi
- Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University
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- Takeda Kota
- Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University
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- Sasaki Makoto
- Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University
抄録
<p>Flip angle (FA) measurements using the actual flip angle imaging (AFI) method may induce significant errors in ultrahigh fields. We aimed to develop a method for detecting errors in FA measurements using phase information at 7 tesla. We performed computer simulations to elucidate the relationship between the FA calculation errors and the phase difference between the two AFI source images. We then examined whether a method based on the phase difference could detect FA calculation errors and determine the prescribed nominal FA of the scanner for accurate measurements in phantoms and healthy volunteers. The simulations confirmed that the calculated FA values erroneously decreased when the longitudinal magnetization and phase in one of the source images were inverted. Tests on phantoms and human subjects demonstrated that the phase difference information between the source images with a cut-off of 90° could readily detect FA calculation errors in the AFI method.</p>
収録刊行物
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- Magnetic Resonance in Medical Sciences
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Magnetic Resonance in Medical Sciences 23 (1), 102-109, 2024
日本磁気共鳴医学会