Dwyer A J, Knop R H, Hoult D I
J Comput Assist Tomogr. 1985 Jan-Feb;9(1):16-8. doi: 10.1097/00004728-198501000-00003.
Chemical shifts may be expressed as distortions and displacements in magnetic resonance (MR) images. Specifically, in two-dimensional Fourier transform reconstructions such shifts produce visible displacements in the direction of frequency encoding. This is readily observable at 0.26 T with phantoms comprised of in vitro solutions with known chemical shifts and human tissues with disparate fat content. Moreover, frequency shift artifacts are visible in routine abdominal scanning at the interfaces of structures of differing fat content. Two common examples of this involve the vertebral body and intervertebral disk and the kidney and surrounding retroperitoneal fat. Without appropriate changes in gradients, such distortions may be expected to increase with increasing magnetic field strength.
化学位移可表现为磁共振（MR）图像中的畸变和位移。具体而言，在二维傅里叶变换重建中，此类位移会在频率编码方向上产生可见的移位。使用由具有已知化学位移的体外溶液和脂肪含量不同的人体组织组成的体模，在0.26 T时很容易观察到这一点。此外，在常规腹部扫描中，不同脂肪含量结构的界面处可见频移伪影。两个常见的例子涉及椎体和椎间盘以及肾脏和周围的腹膜后脂肪。如果不适当改变梯度，预计此类畸变会随着磁场强度的增加而增加。
