Since the use of implanted imaging-opaque markers will permit us to establish the gold standard against which the validity of our non-invasive image analysis algorithms can be evaluated, as well as permit us to study the efficacy of using in vivo, image-derived measures of function for predicting regional myocardial viability, marker implanting experiments were performed in fasting mongrel dogs. Paired endocardial and epicardial markers were placed in four locations on the canine heart, with each pair being attached by elastic string which keeps the endocardial and epicardial markers on the respective surfaces during the entire cardiac cycle without restricting myocardial thickening.
The dogs were positioned in the magnet for initial 4D imaging under baseline conditions, according to the MR imaging protocols described below. The left anterior descending coronary was then occluded, without movement of the animals relative to the imaging planes. 4D images were acquired again after the occlusion. This way, we are assured the images are registered with each other pre- and post- occlusion. Details of this experimental model are briefly described in , and will be the subject of several forthcoming papers.