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MRI using a concentric rings trajectory

✍ Scribed by Hochong H. Wu; Jin Hyung Lee; Dwight G. Nishimura

Book ID
102953976
Publisher
John Wiley and Sons
Year
2007
Tongue
English
Weight
969 KB
Volume
59
Category
Article
ISSN
0740-3194

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✦ Synopsis

Abstract

The concentric rings two‐dimensional (2D) k‐space trajectory provides an alternative way to sample polar data. By collecting 2D k‐space data in a series of rings, many unique properties are observed. The concentric rings are inherently centric‐ordered, provide a smooth weighting in k‐space, and enable shorter total scan times. Due to these properties, the concentric rings are well‐suited as a readout trajectory for magnetization‐prepared studies. When non‐Cartesian trajectories are used for MRI, off‐resonance effects can cause blurring and degrade the image quality. For the concentric rings, off‐resonance blur can be corrected by retracing rings near the center of k‐space to obtain a field map with no extra excitations, and then employing multifrequency reconstruction. Simulations show that the concentric rings exhibit minimal effects due to T modulation, enable shorter scan times for a Nyquist‐sampled dataset than projection‐reconstruction imaging or Cartesian 2D Fourier transform (2DFT) imaging, and have more spatially distributed flow and motion properties than Cartesian sampling. Experimental results show that off‐resonance blurring can be successfully corrected to obtain high‐resolution images. Results also show that concentric rings effectively capture the intended contrast in a magnetization‐prepared sequence. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.

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