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.