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Method for spatially interleaving two images to halve EPI readout times: Two reduced acquisitions interleaved (TRAIL)

Priest, AN; Carmichael, DW; De Vita, E; Ordidge, RJ; (2004) Method for spatially interleaving two images to halve EPI readout times: Two reduced acquisitions interleaved (TRAIL). MAGN RESON MED , 51 (6) 1212 - 1222. 10.1002/mrm.20085.

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Abstract

A new MRI method is presented that can generate images using half the normal readout time or, more usefully, half the number of phase-encode steps, combining two readouts per excitation. However, the corresponding data are interleaved in image space-not in k-space, as in many other fast techniques. This gives a resilience to the phase-related artifacts that can occur in many other techniques due to subject motion. A modified stimulated-echo experiment is used to create two low-resolution images from a single sequence. The magnetization that contributes to these images is nonuniformly distributed within each pixel, forming two sinusoidal waves in quadrature, with an oscillation period of exactly two pixels. Since only half of each pixel contributes significant signal, the two images can be interleaved to create a full image with twice as many pixels and double the resolution. When the technique is used in the phase-encode direction, the effective imaging time is halved, though with two readouts per TR period. When two half-length echo-planar readouts are used, the method can also reduce blurring and distortion by halving the effective readout time for echo-planar imaging (EPI). For even further improvements, the technique can be combined with partial Fourier or parallel imaging. (C) 2004 Wiley-Liss, Inc.

Type:Article
Title:Method for spatially interleaving two images to halve EPI readout times: Two reduced acquisitions interleaved (TRAIL)
DOI:10.1002/mrm.20085
Keywords:fast imaging, interleaved images, stimulated echo, TRAIL, EPI, STIMULATED ECHO, PHASE ACQUISITION, COMPOSITE ECHOES, SPIN ECHOES, MR, T-1, DIFFUSION, NMR
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Neurology
UCL > School of BEAMS > Faculty of Engineering Science > Medical Physics and Bioengineering

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