Time series analysis of in vivo cardiac MRI-PET image fusion of the human amniotic mesenchymal stem cell (hAMSC) engraftment
K. Diedrich, Yuka Matsuura, Nicholas Herlambang, Rajesh Dash, Phillip Chung-Ming Yang · Journal of Cardiovascular Magnetic Resonance · 2014
Methods Porcine ischemia reperfusion (IR) injury model was employed to assess the successful stem cell engraftment signal by manganese enhanced MRI (MEMRI). To validate the MEMRI signal, hAMSCs were transduced by PET reporter gene (RG) utilizing the herpes simplex virus-thymidine kinase transgene construct, which is expressed only in engrafted cells to trap 18F-FHBG radiotracer. One week after IR injury, the RG transduced hAMSCs were delivered via transendocardial injection into periand intra-infarct regions. PET-CT and MR locator-MEMRI-delayed enhanced MRI (DEMRI) images were acquired post hAMSC injection on days 0, 7, and 45. All pairs of CT and MR locator images were registered by gradient descent to optimize mutual information between the images generating transformation matrixes. These transformation matrixes were used to align PET with MEMRI and DEMRI and longitudinal images into common frames of reference. Additionally image pairs were fused into a single display. An ROI around the engrafted stem cells on MEMRI was copied to the same location on PET-CT longitudinally and average intensity was sampled at each time point.