Improved cardiac sodium MR imaging by density-weighted phase-encoding.
OBJECTIVE
To show that density-weighted (DW) k-space sampling improves the quality of human cardiac sodium imaging, a novel method was implemented that combines the high signal-to-noise efficiency of three-dimensional phase-encoding with the advantageous localization performance of nonuniform sampling. A simulation demonstrates substantially reduced blood contamination in the myocardium.


METHODS
At 2.0 T, DW cardiac "fast" sodium images with a voxel size of 844 microL in seven minutes and "high-resolution" scans in 30 minutes with a voxel size of 570 microL were acquired. For comparison, conventional gradient-echo imaging was also performed.


RESULTS
In the DW images, a myocardial signal-to-noise ratio (SNR) of 16.0 in the left ventricle and 8.5 in the septum (N = 4) was measured. With longer experimental duration (about 30 minutes; N = 3), the image quality and the SNR could be further improved (voxel size: 570 microL; SNR: blood 16.1, septum 10.6). Compared to the gradient-echo images, the image quality was substantially improved.


CONCLUSIONS
This new method for human cardiac sodium imaging provides high image quality combined with optimal sensitivity and thus may improve the clinical applicability of 23Na cardiac MRI.
Greiser
Andreas
A
Department of Biophysics, University of Würzburg, Würzburg, Germany. andreas.greiser@siemens.com
Haase
Axel
A
von Kienlin
Markus
M
D003198:Computer Simulation; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009206:Myocardium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D012975:Sodium Isotopes
D012975:Sodium Isotopes; D012964:Sodium