In vivo imaging studies in animal models of myocardial infarction with and without cell injections

After prolonged myocardial ischemia, myocardial infarction occurs. Several tissue changes are associated with myocardial infarction and iron labeled cell injections. In the present thesis our major aim was to develop methods to monitor these tissue changes with MRI and MDCT.

In the first chapter we used transendocardial injection to deliver iron labeled allogen skeletal myoblasts one week after myocardial infarction. Our goal was to identify the cells and/or injection sites in the myocardium. We used our new Tissue Characterization Mapping method to delineate tissue edema and hemorrhage in the myocardium.

The T2 weighted signal intensity enhancement, T2w SIE region was reported to represent area at risk in the acute animal infarct model. We investigated the use of multi modality imaging in the peri infarct region that was delineated with the help of T2 weighted images in subacute infarction. In short, myocardial perfusion and strain analysis of peri infarct myocardium as defined by T2w signal intensity enhancement (SIE) were used to characterize this region.

Another important post ischemia tissue change, microvascular obstruction, was also investigated with Multidetector Computed Tomography. Such regions indicate worse than average clinical outcome. We identified and quantified this tissue alteration in the hope of predicting and grading the morbidity after myocardial infarction.

Additionally we performed a short and long term toxicity study to investigate the physiological effect of our tissue persistent contrast agent, Gd(ABE-DTTA), which was used in our dog experiments and could be a promising contrast agent for future clinical use.