Online motion correction for diffusion-weighted imaging using navigator echoes: Application to RARE imaging without sensitivity loss.
This article describes the first application of true online motion correction to diffusion-weighted RARE imaging. Two orthogonal navigator echoes were acquired and zeroth and first-order phase corrections applied in less than 8 ms between a diffusion-weighted magnetization preparation and data acquisition using the RARE sequence. The zeroth-order phase correction was realized by pulsing the system's B(0)-coil: the first-order error corrected with appropriate magnetic field gradient pulses. Online correction ensured that no irreversible signal loss could occur in the imaging experiment. Diffusion-weighted images of the brain were obtained from healthy volunteers. EGG-triggered acquisition was applied at 400 ms after the R-wave. Data were acquired on a matrix of 256 x 256 with a RARE factor of 16 and a b-value of 804 smm(-2). The images obtained with online motion correction showed a remarkably high image quality, while those acquired without motion correction were severely degraded by artifacts.
Norris
D G
DG
Max-Planck-Institute of Cognitive Neuroscience, Leipzig, Germany. norris@cns.mpg.de
Driesel
W
W
D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement; D019047:Phantoms, Imaging