Joseph
Y. Cheng1, Marcus T. Alley2, Charles H. Cunningham3,
4, Shreyas S. Vasanawala2, John M. Pauly1,
Michael Lustig5
1Electrical Engineering, Stanford University, Stanford, CA, United States; 2Radiology, Stanford University, Stanford, CA, United States; 3Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; 4Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; 5Electrical Engineering and Computer Science, University of California, Berkeley, CA, United States
MR scans are sensitive to motion effects due to the scan duration. On a sufficiently small spatial-scale, the complex non-rigid motion can be well approximated as simple linear translations. This formulation allows for a practical autofocusing algorithm that locally minimizes a given motion metric -- more specifically, the proposed localized gradient-entropy metric. To reduce the vast search space for an optimal solution, possible motion paths are limited to motion measured from multi-channel Butterfly navigation data. The correction scheme is applied to free-breathing abdominal patient studies. A reduction in artifacts from non-rigid motion is observed.