Using a generalized population based approach to estimate input function from incomplete blood sampling data in quantitative dynamic FDG PET studies

Objectives: To validate and optimize a novel population-based plasma input function (PIF)estimation method for noninvasive quantification of dynamic F-18-FDG PET imaging with sparsely sampled PIF Methods : Eight 60-min monkey dynamic F-18-FDG PET studies with arterial blood sampling were performed. Time activity curves (TACs) of 7 cerebral regions of interests (ROIs) were generated from each study. A generalized population-based approach to recover full kinetics of PIF from a given sparsely sampled blood data was proposed. The estimated PIF (ePIF) from the incomplete sampling data was determined by either interpolation or extrapolation method using scale calibrated population mean of normalized PIF. The leave-one-out cross validation method was used to generate mean PIF for each subject. The Patlak plot was applied ROI TACs to estimate F-18-FDG uptake rate constant Ki. The Ki estimated from measured PIF (mPIF) was used as reference. With given sample size, the PIFs were estimated from different blood sampling schemes. The optimal blood sample protocol with the given sample size was determined by statistical analysis of Ki estimates from ePIF and mPIF. Results : The linear correlations between the Ki estimates from ePIF with optimal sampling schemes and those from measured PIF were: Ki(ePIF 1 simple at 40 min) = 0.97 Ki(mPIF) -0.00; Ki(ePIF 2 simples at 40 and 50 min) = 0.96Ki(mPIF) - 0.00; Ki(ePIF 3 simples at 12, 40, and 50 min) = 0.98Ki(mPIF) - 0.00; and Ki(ePIF 4 simples at 10, 25, 40, and 50 min) = 0.99Ki(mPIF)-0.00. As sample size become greater or equal 4, the Ki estimates from ePIF with its corresponding optimal sampling protocol were almost identical to those from mPIF. Conclusions : The generalized population-based PIF estimation method with optimal blood sampling scheme is a reliable method to estimate PIF from incomplete blood sampling data for quantification of dynamic FDG PET imaging using the Patlak plot. Key words: Plasma input function; Dynamic F-18-FDG PET imaging; Time activity curves; Regions of interests; Monkey