Rapid autocorrection using prescan navigator echoes.
Autocorrection is an adaptive motion correction algorithm that does not require an in vivo measurement of the motion record. A novel method for ensuring convergence of this algorithm when motion is severe is presented. A limited number of navigator echoes are acquired before the imaging sequence to obtain a "snapshot" of the object. Phase differences between the navigator and image k-space data are used as an estimate of motion-induced phase shifts in the image, followed by autocorrection. In phantom data a six-fold reduction in computation time compared to autocorrection alone was realized. These results indicate that this navigator/autocorrection combination may be useful for reducing motion artifacts and computation time for MR exams when motion along the image phase encoding axis is severe.
McGee
K P
KP
Department of Diagnostic Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.
Felmlee
J P
JP
Manduca
A
A
Riederer
S J
SJ
Ehman
R L
RL
D000465:Algorithms; D016477:Artifacts; D001331:Automation; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008962:Models, Theoretical; D009038:Motion; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D014953:Wrist / Q000473:pathology