Dixon W T, Engels H, Castillo M, Sardashti M
Frederik Philips Magnetic Resonance Research Center, Department of Radiology, Emory University, Atlanta, Georgia 30322.
Magn Reson Imaging. 1990;8(4):417-22. doi: 10.1016/0730-725x(90)90050-c.
Radio frequency magnetic fields from 5 to 100 kHz off resonance reduce longitudinal magnetization of water in some tissues without affecting the magnetization of simple solutions (Wolff, S.D.; Balaban, R.S. Magnetization transfer contrast (MTC) and tissue water proton relaxation in vivo. Magn. Reson. Med. 10:135-144; 1989). We demonstrate that off resonant fields used in day to day multislice imaging have a significant effect. Extra slices reduced brain (gray and white matter) and muscle intensities 10%-20% relative to fat, water, and paramagnetic solutions, a larger effect than produced by slice overlap. Implications for image contrast and quantitation are discussed.
