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Optimizing the acceleration and resolution of three‐dimensional fat image navigators for high‐resolution motion correction at 7T
Author(s) -
Gallichan Daniel,
Marques José P.
Publication year - 2017
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26127
Subject(s) - acceleration , image resolution , temporal resolution , magnetic resonance imaging , resolution (logic) , image quality , motion (physics) , computer science , artificial intelligence , nuclear magnetic resonance , computer vision , physics , nuclear medicine , image (mathematics) , optics , medicine , radiology , classical mechanics
Purpose To investigate the effect of spatial resolution and parallel imaging acceleration factor on the quality of the motion estimates derived from image navigators with a three‐dimensional (3D) gradient‐recalled echo (GRE) acquisition with fat excitation (3D FatNavs) for neuroimaging at 7T. Methods Six healthy subjects were scanned for 10 min, during which time repeated GRE volumes were acquired during small movements—alternating between fat and water excitations (WaterNavs)—allowing retrospective decimation of the data to simulate a variety of combinations of image resolution and acceleration factor. Bias and error in the motion estimates were then compared across navigator parameters. Results The 2‐mm, 4 × 4 accelerated data (TR volume = 1.2 s) provided motion estimates that were almost indistinguishable from those from the full original acquisition (2 mm, 2 × 2, TR volume = 5.2 s). For faster navigators, it was found that good accuracy and precision were achievable with TR volume = 144 ms, using a lower spatial resolution (4 mm, 6 × 6 acceleration) to avoid the bias observed at exceptionally high acceleration factors (8 × 8 or higher). Parameter estimates from WaterNavs and FatNavs showed close agreement with FatNavs, with better performance at exceptionally high acceleration factors. Conclusion Our data help to guide the parameter choice for 3D FatNavs when a compromise must be reached between the quality of the motion estimates and the available scan time. Magn Reson Med 77:547–558, 2017. © 2016 International Society for Magnetic Resonance in Medicine