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Abstract #0309

FatNavs: Exploiting the Natural Sparsity of Head Fat Images for High-Resolution Motion-Navigation at Very High Acceleration Factors

Daniel Gallichan1, Jos P. Marques2, Rolf Gruetter3, 4

1LIFMET, Ecole Polytchnique Fdrale de Lausanne, Lausanne, Vaud, Switzerland; 2Dept. of Radiology, University of Lausanne, Lausanne, Vaud, Switzerland; 3LIFMET, cole Polytechnique Fdrale de Lausanne, Lausanne, Vaud, Switzerland; 4Depts. of Radiology, Universities of Lausanne and Geneva, Lausanne, Vaud, Switzerland

We tested the feasibility of using the fat signals in the head for high-resolution motion-navigation at very high acceleration factors. 6 subjects were scanned at high resolution with both fat and water excitations at 3 time-points during a single session where there was no intentional movement. The registration of the water images was used as the reference for motion, and the parameters extracted from the fat images, both fully sampled and accelerated to R=50, were compared. Although consistent results were obtained from the fat images, there was a tendency to slightly underestimate the true motion which requires further investigation.

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Keywords

accelerated acceleration accurate achieve acquisition actual affected align allow allowing altered assumed assumption bias binomial body brain cause channels clear close closest coil collected combination compliant compress consistency contrast correct crosses cushioning definition depends detrimental discrepancy distributed duration early effective either encodes especially estimation example excessive excitation exist expect expected experiment exploiting extended extracted feasibility features foundations full fully gaps give gold gradient hardware head healthy highly host implies influence insertion instructed intentional involuntary least linearities longer loss magnetization major marques matrix minutes motion natural navigation navigator negligible nova pairs perturbation plotted potential preliminary proof prospectively pseudo pure quality radial radiology rage readouts reconstructed reconstruction reflect registered registration regularized remove require resolution retaining retrospectively rigid rotations sampled scalp sense sensing sensitivity sessions short simulated smith space sparsity spent sphere spokes step still structural subject subjects system tend tendency thereby throughout tight tools towards tracking typical typically volume volumes water whole young