Irene Paola Ponce1, Martin Blaimer2,
Felix Breuer2, Peter Michael Jakob1,2, Mark A. Griswold3,
Peter Kellman4
1Experimental Physics 5, University of
Wrzburg, Wrzburg, Bavaria, Germany; 2Research Center Magnetic
Resonance Bavaria (MRB), Wrzburg, Bavaria, Germany; 3Department
of Radiology, University Hospitals of Cleveland and Case Western Reserve
University, Cleveland, OH, United States; 4Laboratory of Cardiac
Energetics, National Institutes of Health, National Heart, Lung and Blood
Institute, Bethesda, MD, United States
Many
of Parallel MRI techniques are based on a time-interleaved acquisition scheme
and allow dynamic imaging with high frame rates. In addition, in order to
improve the SNR, the temporal average (also referred to as direct current,
DC) is subtracted from the raw data so that only the dynamics of the object
is reconstructed. In this work we demonstrate that DC subtraction may lead to
temporal filtering effects in form of signal nulls in the temporal frequency
spectra of the reconstructed images. We propose to correct the DC by an
additional GRAPPA reconstruction prior to subtraction from the raw data.