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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Artifacts, Computer Simulation, Contrast Media, Feasibility Studies, Gadolinium DTPA, Humans, Image Enhancement, Imaging, Three-Dimensional, Liver, Magnetic Resonance Imaging, Phantoms, Imaging, Respiratory-Gated Imaging Techniques.
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Do enhancement of respiratory navigator-gated three-dimensional spoiled gradient-recalled echo sequence with variable flip angle scheme? Context: To develop and demonstrate the feasibility of a new technique for respiratory-gated, fat-suppressed, three-dimensional spoiled gradient-recalled echo (3D-SPGR) with navigator gating for more accurate and robust motion detection. A navigator-gated 3D-SPGR technique was modified to include a wait period immediately prior to the navigator sequence for magnetization recovery. Furthermore, a variable flip angle scheme was realized by a combination of ramp-up, ramp-down, and attenuation strategies for optimizing point spread functions. Phantom and human experiments were conducted with our technique on 1.5T scanners. Using the method, T1-weighted 3D images with improved signal homogeneity were acquired with a maximum flip angle of 30° in phantom and human tests. Also, compared with the conventional navigator-gated 3D-SPGR, accurate respiratory motion detection of free-breathing subjects was provided, leading to reduced motion artifacts.
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The combination of wait insertion and the variable flip angle method improved both motion detection accuracy and image homogeneity in a navigator-gated 3D-SPGR study. Final Decision: yes