(Circulation. 2001;103:e84.)
© 2001 American Heart Association, Inc.
Images in Cardiovascular Medicine |
Cine Magnetic Resonance Imaging of Myocardial Ischemia and Reperfusion in Mice
From the Departments of Biomedical Engineering (Z.Y., B.A.F., W.D.G., A.J.R., J.N.O.) and Radiology (S.S.B.), University of Virginia Health System, Charlottesville, Va.
Correspondence to Stuart S. Berr, PhD, Department of Radiology, University of Virginia Health Sciences Center, MR4 Building, Room 1192, PO Box 801332, Charlottesville, VA 22908. E-mail berr{at}virginia.edu
Studies of acute myocardial ischemia/reperfusion injury in genetically manipulated mice have been impeded by the technical challenges of instrumenting small animals (<40 g) and assessing cardiac function at such rapid heart rates (>500 bpm). To address these problems, 4 C57BL/6 mice (28 to 30 g) were anesthetized with pentobarbital and intubated for surgical instrumentation of the major left coronary artery with pneumatically controlled balloon occluders. The distal end of the tubing from the balloon occluder was exteriorized at the back of the neck. One week later, each mouse was anesthetized with pentobarbital and fitted with surface ECG electrodes, and an extension tube was added to the balloon occluder. Mice were imaged on a Varian Inova 4.7T MR scanner using a Helmholtz radiofrequency coil. An ECG-triggered, 2D gradient echo sequence with an echo time of 3.9 ms and a flip angle of 20 degrees was used to obtain 12 phases per cardiac cycle at a final resolution of 100x100x1000 µm3.
Baseline cine images consisted of a series of 7
contiguous, 1-mm-thick, short-axis slices spanning the heart from apex
to base. A myocardial stunning protocol consisting of a series of four
4-minute coronary occlusions interspersed with 4 minutes of reperfusion
was then executed from a remote position outside of the magnet.
Contiguous, short-axis cine MR images were successively acquired in the
midventricular to apical regions of the left ventricle during each of
the 4 balloon inflations. As shown in the
Figure
and the accompanying cine images, the use of remotely controlled
coronary occluders, combined with high-field MRI for the noninvasive
assessment of cardiac function, should prove valuable for elucidating
the role of specific genes in the pathophysiology of
ischemia/reperfusion injury using genetically manipulated
mice.
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Footnotes
Cine images of Figure
can be found at www.circulationaha.org
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