Reduction of signal fluctuation in functional MRI using navigator echoes.
Functional magnetic resonance imaging is sensitive to signal fluctuations due to physiological motion and system instability. In this paper, motion-related signal fluctuations are studied, and a method that uses navigator echoes to monitor and compensate for signal fluctuations in a gradient-echo sequence is described. The technique acquires a "navigator" signal before the application of the phase-encoding and readout gradients and corrects the phase of the subsequently acquired imaging data. This technique was implemented on a 4 Tesla whole body system and validated on normal volunteers. With this technique, temporal fluctuations in image intensity were substantially reduced and improved functional activation maps were obtained.
Hu
X
X
Department of Radiology, University of Minnesota Medical School, Minneapolis 55455.
Kim
S G
SG
D016477:Artifacts; D002555:Cerebrospinal Fluid; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009044:Motor Cortex / Q000033:anatomy & histology; D009048:Motor Skills / Q000502:physiology; D009068:Movement; D010775:Photic Stimulation; D012119:Respiration; D014793:Visual Cortex / Q000033:anatomy & histology