Parametric Methods for Dynamic C-11-Phenytoin PET Studies

In this study, the performance of various methods for generating quantitative parametric images of dynamic C-11-phenytoin PET studies was evaluated. Methods: Double-baseline 60-min dynamic C-11-phenytoin PET studies, including online arterial sampling, were acquired for 6 healthy subjects. Parametric images were generated using Logan plot analysis, a basis function method, and spectral analysis. Parametric distribution volume (V-T) and influx rate (K-1) were compared with those obtained from nonlinear regression analysis of time-activity curves. In addition, global and regional testretest (TRT) variability was determined for parametric K-1 and V-T values. Results: Biases in V-T observed with all parametric methods were less than 5%. For K-1, spectral analysis showed a negative bias of 16%. The mean TRT variabilities of V-T and K-1 were less than 10% for all methods. Shortening the scan duration to 45 min provided similar V-T and K-1 with comparable TRT performance compared with 60-min data. Conclusion: Among the various parametric methods tested, the basis function method provided parametric V-T and K-1 values with the least bias compared with nonlinear regression data and showed TRT variabilities lower than 5%, also for smaller volumeof- interest sizes (i.e., higher noise levels) and shorter scan duration.