Nicole Seiberlich1, Philipp Ehses2,
Jeffrey L. Duerk, 1,3, Robert Gilkeson1, Mark A.
Griswold1,3
1Radiology, Case Western Reserve University,
Cleveland, OH, United States; 2Experimentelle Physik V,
Universitaet Wuerzburg, Wuerzburg, Germany; 3Biomedical
Engineering, Case Western Reserve University, Cleveland, OH, United States
While
standard radial GRAPPA can be used to reconstruct images with low
undersampling factors, its primary assumption (that segments of the radial
lines can be approximated as Cartesian) breaks down at high acceleration
factors. A new through-time calibration method has recently been proposed;
this method yields high image quality, but requires large numbers of
calibration frames. The method proposed here uses through-k-space segments as
well as repetitions through time to reduce the number of calibration frames
needed while maintaining image quality. This hybrid radial GRAPPA calibration
method is demonstrated for real-time, ungated cardiac acquisitions with frame
rates of 43 ms.