Correction of Geometrical Distortions in MR-images

Summary

In MR-Fourier Imaging three different types of magnetic fields are used: a homogeneous main magnetic field, linear and orthogonal gradient fields, and a homogeneous radiofrequency (RF) field. If these fields deviate from their ideal configurations, artifacts and disturbances in the MR-images will occur. An inhomogeneous RF-field leads to intensity variations in the MR-images. Inhomogeneities of the main magnetic field and spatial nonlinearity of the field gradients introduce geometrical image distortions. Although these distortions often are not obvious in clinical images, it might be necessary to do a distortion correction in order to get precise spatial information from the image. Precise spatial information about tumors and other lesions is very important for stereotaxis and for the future role of MR-imaging in nuclear therapy planning.