3D multiphase MR tagged imaging of canine cardiomyoplasty

Cardiomyoplasty (CMP) is a relatively new procedure which is being developed in order to assist patients with chronic heart failure. Previous research on this procedure is inconclusive due, in large part, to a lack of understanding of the mechanism of CMP. The purpose of this study is to use novel MR imaging and analysis tools to gain an understanding of the function of CMP by measuring strain changes in the wrap directly. Using a canine model of heart failure, we have generated high-resolution tissue displacement data using an MR tissue tagging, 3D multiphase imaging sequence implemented on a 4 Tesla scanner. Material displacement of the wrap and the myocardium was estimated using an optical flow algorithm on data acquired before and after wrap stimulation. Strain was seen to increase significantly in the proximal portion of the wrap as well as in the anterior lateral freewall. There was no change in the distal section of the wrap and a small decrease in strain of the posterior septal wall. This causes a large translation of the heart without radial “squeezing”, with little effect on left ventricular ejection fraction. However, this indicates that the heart was able to maintain stroke volume while doing less work