Comprehensive cardiovascular magnetic resonance of myocardial mechanics in mice using three-dimensional cine DENSE.
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 E(rr), E(cc), and E(ll), respectively. Peak end-systolic values for the shear strains were 0.00 ± 0.08, 0.04 ± 0.12, and 0.03 ± 0.07 for E(rc), E(rl), and E(cl), respectively. The peak end-systolic normalized torsion was 5.6 ± 0.9°.


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.
MR R&D Collaborations, Siemens Healthcare, Atlanta, USA.
Xiaodong
X
Zhong
Lauren B
LB
Gibberman
Bruce S
BS
Spottiswoode
Andrew D
AD
Gilliam
Craig H
CH
Meyer
Brent A
BA
French
Frederick H
FH
Epstein
D000818:Animals; D001696:Biomechanical Phenomena; D006352:Heart Ventricles / Q000033:anatomy & histology*; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D019028:Magnetic Resonance Imaging, Cine; D051379:Mice; D008810:Mice, Inbred C57BL; D009200:Myocardial Contraction; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left