Phase constrained encoding (PACE): a technique for MRI in large static field inhomogeneities.
In spin echo imaging, magnetization is assigned to a location defined by its frequency of rotation. In the presence of a static magnetic field inhomogeneity, however, this location does not correspond to the true location of the magnetization. This paper describes a magnetic resonance imaging technique called phase constrained encoding (PACE) that assigns magnetization to its true location through the use of a spin echo train and alternating readout gradients. Small artifactual side-bands occur in the point spread function but can be minimized or eliminated using higher gradient strengths, more echoes, and/or additional acquisitions. Implementation of a simple version of this technique confirms simulations.
Kim
J K
JK
Department of Medical Biophysics, University of Toronto, Ontario, Canada.
Plewes
D B
DB
Henkelman
R M
RM
D016477:Artifacts; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural; D012815:Signal Processing, Computer-Assisted