  Radial imaging techniques, such as projection-reconstruction (PR), are used
in magnetic resonance imaging (MRI) for dynamic imaging, angiography, and
short-imaging. They are robust to flow and motion, have diffuse aliasing
patterns, and support short readouts and echo times. One drawback is that
standard implementations do not support anisotropic field-of-view (FOV) shapes,
which are used to match the imaging parameters to the object or
region-of-interest. A set of fast, simple algorithms for 2-D and 3-D PR, and
3-D cones acquisitions are introduced that match the sampling density in
frequency space to the desired FOV shape. Tailoring the acquisitions allows for
reduction of aliasing artifacts in undersampled applications or scan time
reductions without introducing aliasing in fully-sampled applications. It also
makes possible new radial imaging applications that were previously unsuitable,
such as imaging elongated regions or thin slabs. 2-D PR longitudinal leg images
and thin-slab, single breath-hold 3-D PR abdomen images, both with isotropic
resolution, demonstrate these new possibilities. No scan time to volume
efficiency is lost by using anisotropic FOVs. The acquisition trajectories can
be computed on a scan by scan basis.
