Jens-Peter Khn1, 2, James H. Holmes3, Diego Hernando1, Scott B. Reeder1, 4
1Department of Diagnostic Radiology, University of Wisconsin-Madison, Madison, WI, United States; 2Department of Diagnostic Radiology, University Greifswald, Greifswald, MV, Germany; 3Global Applied Science Laboratory, GE Healthcare, Madison, WI, United States; 4Medical Physics, Biomedical Engineering and Medicine, University of Wisconsin-Madison, Madison, WI, United States
This work optimizes the excitation flip angle of a navigator pencil-beam to maximize optimal liver/lung contrast while avoiding saturation artifacts in the liver. We used an investigative navigator-gated T1-weighted 3D GRE sequence under clinical conditions for gadoxetic acid-enhanced liver MRI in the hepatobiliary phase. The presence of saturation artifacts and the optimal navigator flip angle are highly dependent on the imaging flip angle and the presence of gadolinium in the liver. Using an imaging flip angle of 30o, 20-60 minutes after gadoxetic acid, the optimal navigator flip angle is 90o, without any appreciable saturation artifact.