Variable density and anisotropic field-of-view for 3D Stack-of-Stars radial imaging
Joao Tourais (TU Delft - ImPhys/Weingärtner group, Philips Innovation Services, Eindhoven University of Technology)
Guruprasad Krishnamoorthy (Eindhoven University of Technology, Philips Innovation Services)
Jouke Smink (Philips Innovation Services)
Marcel Breeuwer (Eindhoven University of Technology, Philips Innovation Services)
Marc Kouwenhoven (Philips Innovation Services)
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Abstract
Objective: To develop a non-iterative method for applying elliptical field-of-view (FOV) to radial imaging and evaluate it for Stack-Of-Stars (SOS) with variable radial density in the kz direction. Materials and methods: New analytic expressions were derived to compute the radial profile angles for an elliptical FOV with and without golden angle sampling. With a major-to-minor-axis FOV ratio of 1:0.5, anisotropic FOV and variable density SOS were evaluated, using point spread function analysis, phantom imaging, and in vivo pelvic imaging. Results: Compared with conventional SOS, elliptical density in kz reduced scan time by 20%, while maintaining similar levels of radial aliasing artifacts. Anisotropic FOV reduced scan time by 31%, resulting in similar levels of radial aliasing artifacts at low undersampling for objects with matching in-plane anisotropy. Combining both techniques resulted in a 45% scan time reduction. Alternatively, when compared to conventional SOS using identical scan time, variable density and anisotropic FOV both displayed a lower level of radial aliasing artifacts, although for anisotropic FOV this effect was less pronounced at higher undersampling. Discussion: Variable density and anisotropic FOV can reduce scan time and/or reduce aliasing artifacts for SOS. The new analytical expressions for elliptical FOV will facilitate future studies on anisotropic FOV radial imaging.
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