Hybrid SPECT/cardiac‐gated first‐pass perfusion CT: locating transplanted cells relative to infarcted myocardial targets

Purpose A challenge with cardiac cell therapy is determining the location of cells relative to infarct tissue. As cells are viable following 111In-labeling, and first-pass CT imaging can identify regions of myocardial infarction, we evaluated the feasibility of a SPECT/CT system to localize cells relative to infarcted myocardium in a canine model. Methods Ten canines underwent surgical ligation of the left-anterior-descending artery and endothelial progenitor cells labeled with 111In-tropolone were transplanted endocardially or epicardially. SPECT/CT was performed on day of transplantation, 4 and 10 days post-transplantation. For each imaging session first-pass perfusion CT was performed to delineate the area of reduced perfusion. SPECT and first-pass CT images were fused and evaluated. Contrast-to-noise ratios (CNR) were calculated for 111In-SPECT images to evaluate cell detection. Results The zone of reduced perfusion was well delineated on first-pass perfusion CT in all canines. The 111In signal was visualized within this zone in all cases. Analysis of the CNRs suggests that cells may be followed for 11 effective half-lives using the images from first-pass perfusion CT to provide the anatomic landmarks. Conclusion In the setting of an acute myocardial infarction SPECT/[first-pass perfusion CT] is an effective hybrid platform for the localization of cells in relation to the area of reduced blood flow. Copyright © 2012 John Wiley & Sons, Ltd.