Correction of translational motion artifacts in multi-slice spin-echo imaging using self-calibration.
In this paper, we describe a method for detecting and correcting in-plane bulk translational motion in multislice spin-echo imaging using self-calibration and postprocessing. A constant phase encoding offset between slices is used to evenly spread out the low spatial frequency echoes to allow accurate motion detection by self-calibration. Motion detection in both x and y directions is achieved by interchanging the readout and phase encoding directions for the alternate slices. Displacements are determined by cross correlating the modulus of each 1D transformed echo with a reference box car function whose width equals that of the imaged object. In addition, phase errors induced by the velocity in the readout direction are estimated and corrected using the displacement data. The results obtained from knee studies at 0.5 T and 1.5 T show that the artifacts due to translational motions are significantly suppressed upon correction. The method does not require any additional pulses or time, and the data processing can be easily implemented.
Zang
L H
LH
Department of Research and Engineering, Hitachi Instruments, Inc., San Jose, CA 95134.
Fielden
J
J
Wilbrink
J
J
Takane
A
A
Koizumi
H
H
D000465:Algorithms; D016477:Artifacts; D002138:Calibration; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007717:Knee / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008962:Models, Theoretical; D009038:Motion; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors