A Simple Auto Prescan Calibration Method for Multislice Fast Spin Echo MRI

摘要

The image quality of fast spin echo (FSE) is more sensitive than the typical spin echo pulse sequence caused by the eddy current effect. Microsecond-scale misalignment of primary spin echoes produces a large spatial variation in image signal intensity. In this study, we describe an auto prescan calibration method that can improve the FSE image quality and minimize the eddy current effect on the image. We used'a 0.32 T MRI system and obtained phantom and lumbar images. For FSE image correction, the optimal ranges and steps were determined to find the appropriate values, which were added to or subtracted from the gradient area values for each slice. The appropriate value of each slice could be found using the maximum signal intensity when the refocusing gradient area was changed by a number of steps in. the optimal range. The determined value of each slice was applied before each slice image acquisition. The determined optimal step numbers and ranges were applied to in vivo image acquisition, and confirmed the reconstructed image quality. Based on our results, the obtained phantom and lumbar images were shown to be well corrected. The corrected images represented the image quality improvement and elimination of ghosting and blurring artifacts. In conclusion, we have proposed an FSE correction technique that automatically adjusts slice selection for the refocusing gradient balance during prescan, and confirmed that the calibration technique is very reliable even within complex in vivo images. We believe that our proposed technique will greatly benefit in MRI systems.