Parametric Methods for Dynamic ¹¹C-Phenytoin PET Studies.

Abstract

In this study, the performance of various methods for generating quantitative parametric images of dynamic ¹¹C-phenytoin PET studies was evaluated. <b>Methods:</b> Double-baseline 60-min dynamic ¹¹C-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 (<i>K</i>₁) were compared with those obtained from nonlinear regression analysis of time-activity curves. In addition, global and regional test-retest (TRT) variability was determined for parametric <i>K</i>₁ and V_T values. <b>Results:</b> Biases in V_T observed with all parametric methods were less than 5%. For <i>K</i>₁, spectral analysis showed a negative bias of 16%. The mean TRT variabilities of V_T and <i>K</i>₁ were less than 10% for all methods. Shortening the scan duration to 45 min provided similar V_T and <i>K</i>₁ with comparable TRT performance compared with 60-min data. <b>Conclusion:</b> Among the various parametric methods tested, the basis function method provided parametric V_T and <i>K</i>₁ values with the least bias compared with nonlinear regression data and showed TRT variabilities lower than 5%, also for smaller volume-of-interest sizes (i.e., higher noise levels) and shorter scan duration.