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Self-navigated spiral fMRI: Interleaved versus single-shot

✍ Scribed by Gary H. Glover; Song Lai

Book ID
102957520
Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
967 KB
Volume
39
Category
Article
ISSN
0740-3194

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✦ Synopsis

Abstract

This study compares the measured activation volumes in motor cortex as well as the fluctuation noise and off‐resonance characteristics for 1‐, 2‐, and 4‐shot spiral gradient‐recalled echo blood oxygen level dependent contrast functional magnetic resonance imaging (fMRI) acquisitions, under conditions of constant resolution and scan time and with two readout durations. Reconstructions were made with and without self‐navigator correction. It was found that the navigator correction provided a 50% reduction in image fluctuation noise with 4‐shot acquisitions, and that multishot acquisitions perform as well as single‐shot techniques when self‐navigation is employed. An analysis of blurring showed that off‐resonance Af causes blurring when Δ__f__ > 1/(2*T~ad~), where T~ad~ is the readout duration. Off‐resonance effects were readily corrected during reconstruction with retrospective linear shim, even with the longer readout duration needed for single‐shot methods. With navigator and shim correction, single‐shot and multishot spiral methods are highly effective for fMRI acquisitions.

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