Browsing by Author "Meyer, Craig"

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    Comparison of SNR efficiencies and strain for cine DENSE using conventional EPI, flyback EPI and spiral k-space trajectories
    (BioMed Central Ltd, 2011) Zhong, Xiaodong; Spottiswoode, Bruce; Meyer, Craig; Epstein, Frederick
    The original implementation of 2D cine DENSE (displacement encoding with stimulated echoes) employed a conventional EPI k-space trajectory for rapid data sampling. Follow-up studies used flyback EPI to reduce image artifacts. More recently a spiral k-space trajectory was utilized for improved SNR.
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    Comprehensive Cardiovascular magnetic resonance of myocardial mechanics in mice using three-dimensional cine DENSE
    (BioMed Central Ltd, 2011) Zhong, Xiaodong; Gibberman, Lauren; Spottiswoode, Bruce; Gilliam, Andrew; Meyer, Craig; French, Brent; Epstein, Frederick
    BACKGROUND: Quantitative noninvasive imaging of myocardial mechanics in mice enables studies of the roles of individual genes in cardiac function. We sought to develop comprehensive three-dimensional methods for imaging myocardial mechanics in mice. METHODS: A 3D cine DENSE pulse sequence was implemented on a 7T small-bore scanner. The sequence used three-point phase cycling for artifact suppression and a stack-of-spirals k-space trajectory for efficient data acquisition. A semi-automatic 2D method was adapted for 3D image segmentation, and automated 3D methods to calculate strain, twist, and torsion were employed. A scan protocol that covered the majority of the left ventricle in a scan time of less than 25 minutes was developed, and seven healthy C57Bl/6 mice were studied. RESULTS: Using these methods, multiphase normal and shear strains were measured, as were myocardial twist and torsion. Peak end-systolic values for the normal strains at the mid-ventricular level were 0.29 +/- 0.17, -0.13 +/- 0.03, and -0.18 +/- 0.14 for Err, Ecc, and Ell, respectively. Peak end-systolic values for the shear strains were 0.00 +/- 0.08, 0.04 +/- 0.12, and 0.03 +/- 0.07 for Erc, Erl, and Ecl, respectively. The peak end-systolic normalized torsion was 5.6 +/- 0.9degrees. CONCLUSIONS: Using a 3D cine DENSE sequence tailored for cardiac imaging in mice at 7 T, a comprehensive assessment of 3D myocardial mechanics can be achieved with a scan time of less than 25 minutes and an image analysis time of approximately 1 hour.