• Christine S Law and Gary H Glover.
• Department of Radiology, Center for Advanced MR Technology at Stanford, Stanford University School of Medicine, Stanford, California 94305-5488, USA. cslaw@stanford.edu
• Magn Reson Med. 2009 Sep 1;62(3):829-34.

AbstractThe conventional spiral-in/out trajectory samples k-space sufficiently in the spiral-in path and sufficiently in the spiral-out path to enable creation of separate images. We propose an "interleaved spiral-in/out" trajectory comprising a spiral-in path that gathers one half of the k-space data, and a complimentary spiral-out path that gathers the other half. The readout duration is thereby reduced by approximately half, offering two distinct advantages: reduction of signal dropout due to susceptibility-induced field gradients (at the expense of signal-to-noise ratio [SNR]), and the ability to achieve higher spatial resolution when the readout duration is identical to the conventional method. Two reconstruction methods are described; both involve temporal filtering to remove aliasing artifacts. Empirically, interleaved spiral-in/out images are free from false activation resulting from signal pileup around the air/tissue interface, which is common in the conventional spiral-out method. Comparisons with conventional methods using a hyperoxia stimulus reveal greater frontal-orbital activation volumes but a slight reduction of overall activation in other brain regions.

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