Inherent insensitivity to RF inhomogeneity in FLASH imaging
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MRI as a non-invasive method for studying the internal structure and function of the human body was developed over the past three decades. In MRI, radiofrequency (RF) field inhomogeneity is an unavoidable problem in practice and becomes severe at high magnetic fields due to the dependence of B1 on the sample. It leads to nonuniformities in image intensity and contrast, causing difficulties in quantitative interpretation and image segmentation. In this thesis, we report an interesting observation that the fast low-angle shot (FLASH) sequence, which is often used for anatomic imaging and morphometric studies, can be insensitive to RF inhomogeneity when the same coil is used for both transmission and reception and a proper nominal flip angle is employed. Recommendations also are given for optimum processing procedures for FLASH imaging. This observation can be useful in understanding the signal behavior of FLASH in the presence of RF inhomogeneity and provides a guide for selecting parameters in FLASH imaging.