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Fast Three Dimensional Magnetic Resonance Imaging

1995; Wiley; Volume: 33; Issue: 5 Linguagem: Inglês

10.1002/mrm.1910330510

1522-2594

Pablo Irarrázabal, Dwight G. Nishimura,

Advanced Neuroimaging Techniques and Applications

Abstract To reduce the scan time in three‐dimensional (3D) imaging, the authors consider alternative trajectories for traversing k ‐space. They differ from traditional 3D trajectories, such as 3DFT, in that they employ time‐varying gradients allowing longer readouts and in turn a reduced scan time. Some of these trajectories reduce by an order of magnitude the number of excitations compared with 3DFT and provide flexibility for trading off signal‐to‐noise ratio for scan time. Other concerns are the minimum echo time and flow/motion properties. As examples, the authors show two applications: A 3D data set of the head (field of view of 30 x 30 x 7.5 cm and resolution of 1.5 x 1.5 x 1.5 mm) acquired in 56 s using a stack of spirals in 3D k ‐space; and a 3D movie of the heart (20 x 20 x 20 cm field of view, 2 x 2 x 2 mm resolution, and 16 time frames per cardiac cycle) acquired in 11 min using a cones trajectory.