Chen Weitian, Meyer Craig H
Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA.
Magn Reson Med. 2008 May;59(5):1212-9. doi: 10.1002/mrm.21599.
Spiral scanning is a promising MRI method, but one limitation is that off-resonance effects can cause image blurring. Most current off-resonance correction methods for spiral imaging require an accurate field map, which is difficult to obtain in many applications. Automatic methods can perform off-resonance correction without acquiring a field map. However, these methods are computationally inefficient and relatively prone to estimation error. This study describes a new semiautomatic off-resonance correction method that combines an automatic method with a low resolution field map acquisition for off-resonance correction in spiral scanning. Experiments demonstrate that this method is more robust than conventional automatic off-resonance correction and can provide more accurate off-resonance correction than conventional field map based methods. The proposed method is also computationally efficient and has been implemented for online reconstruction.
螺旋扫描是一种很有前景的磁共振成像（MRI）方法，但一个局限性是失谐效应会导致图像模糊。目前大多数用于螺旋成像的失谐校正方法都需要精确的场图，而在许多应用中这很难获得。自动方法可以在不采集场图的情况下进行失谐校正。然而，这些方法计算效率低且相对容易出现估计误差。本研究描述了一种新的半自动失谐校正方法，该方法将自动方法与低分辨率场图采集相结合，用于螺旋扫描中的失谐校正。实验表明，该方法比传统的自动失谐校正更稳健，并且比传统的基于场图的方法能提供更精确的失谐校正。所提出的方法计算效率也很高，并且已经实现了在线重建。
