Tsuyoshi Matsuda, Yuji Iwadate, Futoshi Mori, Kota Takeda, Makoto Sasaki
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引用次数: 0
Abstract
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.
使用实际翻转角成像(AFI)方法进行翻转角(FA)测量可能会在超高场中产生显著误差。我们的目标是开发一种在 7 特斯拉条件下利用相位信息检测 FA 测量误差的方法。我们进行了计算机模拟,以阐明 FA 计算误差与两个 AFI 源图像之间的相位差之间的关系。然后,我们研究了基于相位差的方法是否能检测出 FA 计算误差,并确定扫描仪的规定标称 FA,以便在模型和健康志愿者身上进行精确测量。模拟证实,当其中一个源图像中的纵向磁化和相位反转时,计算出的 FA 值会错误地降低。对人体模型和人体受试者的测试表明,在 AFI 方法中,以 90° 为截断点的源图像之间的相位差信息可轻松检测出 FA 计算错误。
期刊介绍:
Magnetic Resonance in Medical Sciences (MRMS or Magn
Reson Med Sci) is an international journal pursuing the
publication of original articles contributing to the progress
of magnetic resonance in the field of biomedical sciences
including technical developments and clinical applications.
MRMS is an official journal of the Japanese Society for
Magnetic Resonance in Medicine (JSMRM).