Spiral pulse sequences
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At the time the article was created J. Ray Ballinger had no recorded disclosures.View J. Ray Ballinger's current disclosures
At the time the article was last revised Ammar Haouimi had no recorded disclosures.View Ammar Haouimi's current disclosures
Spiral scanning on MRI is unlike spiral scanning on CT where the x-ray tube is continuously rotating and data is continuously being acquired. On MRI the word "spiral" refers to the pattern of sampling k-space. On conventional imaging sequences including spin echo and gradient echo and on fast imaging sequences, a line or multiple lines of k-space in the frequency direction are acquired consecutively. In spiral scanning, k-space is acquired in a spiral trajectory. The entire k-space can be acquired during a single acquisition, or interleaved using more than one acquisition.
This sequence allows faster image acquisition than the fast echo sequences but is slower than echo-planar imaging. Spiral scanning tends to have fewer artifacts than echo-planar imaging since adjacent points in k-space are acquired in close temporal proximity. The figures to the right show how the acquisition of data in k-space is done with conventional sequences and with spiral scanning.