Comparison of Reconstruction Methods in a Small Animal Cardiac Positron Emission Tomography Study Using a 18F-Labeled Myocardial Agent, [18F] FPTP

Abstract

Background: Reconstruction of positron emission tomography (PET) imagery is essential for accurate diagnosis in nuclear medicine. Thus, several image reconstruction methods were developed to enhance image quality and accuracy. Objectives: We performed PET studies using a new myocardial imaging agent, (5-[18F] fluoropentyl) triphenylphosphonium cation ([18F]FPTP), in left coronary artery (LCA)-occluded rats, and compared the quality of cardiac PET images generated via four reconstruction methods (FBP, OSEM2D, OSEM3D, and 3DRP). Additionally, the infarction size was measured on the polar map of each reconstructed image and compared with defect size measured via 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. Materials and Methods: MicroPET was performed in Sprague-Dawley rats (n = 8) with LCA ligation. Static images were acquired for 30 min after the injection of [18F] FPTP (37 MBq/200 µL) via tail vain. MicroPET images were generated using four different reconstruction methods: filtered backprojection (FBP), two-dimensional or three-dimensional ordered subsets expectation maximization (OSEM2D or OSEM3D), and three-dimensional reprojection (3DRP) algorithm. Image contrast was calculated using the maximum and minimum perfusion values in the polar map. The infarction size was measured on the polar map of each reconstructed image and compared with defect size measured from TTC staining. Results: The location and size of myocardial infarction on PET images correlated closely with that observed with TTC staining. Among the four reconstruction methods, OSEM3D provided the best assessment of infarct size (r2 = 0.994, P < 0.001) and the highest image contrast, performing significantly better than FBP (P = 0.005) and 3DRP (P = 0.005). Conclusion: OSEM3D may provide better image quality and higher contrast than other methods for small animal imaging with the new myocardial imaging agent, [18F] FPTP.