Iterative reconstruction based on median root prior in quantification of myocardial blood flow and oxygen metabolism

The aim of this study was to compare reproducibility and accuracy of two re construction methods in quantification of myocardial blood flow and oxygen metabolism with O-15-labeled tracers and PET. A new iterative Bayesian reco nstruction method based on median root prior (MRP) was compared with filter ed backprojection (FBP) reconstruction method, which is traditionally used for image reconstruction in PET studies. Methods: Regional myocardial blood flow (rMBF), oxygen extraction fraction (rOEF) and myocardial metabolic ra te of oxygen consumption (rMMRO(2)) were quantified from images reconstruct ed in 27 subjects using both MRP and FBP methods. For each subject, regions of interest (ROls) were drawn on the lateral, anterior and septal regions on four planes. To test reproducibility, the ROI drawing procedure was repe ated. By using two sets of ROls, variability was evaluated from images reco nstructed with the MRP and the FBP methods. Results: Correlation coefficien ts of significantly higher in the images reconstructed with the MRP reconst ruction method compared with the images reconstructed with the FBP method ( rMBF: MRP r= 0.896 versus FBP r= 0.737, P< 0.001; rOEF: 0.915 versus 0.855, P < 0.001; rMMRO(2): 0.954 versus 0.885, P < 0.001). Coefficient of variat ion for each parameter was significantly lower in MRP Images than in FBP im ages (rMBF: MRP 23.5% +/- 11.3% versus FBP 30.1% +/- 14.7%, P < 0.001; rOEF : 21.0% +/- 11.1% versus 32.1% +/- 19.8%, P <0.001; rMMRO(2): 23.1% +/- 13. 2% versus 30.3% +/- 19.1%, P < 0.001). Conclusion: The MRP reconstruction m ethod provides higher reproducibility and lower variability in the quantita tive myocardial parameters when compared with the FBP method. This study sh ows that the new MRP reconstruction method improves accuracy and stability of clinical quantification of myocardial blood flow and oxygen metabolism w ith O-15 and PET.