Parametric Methods for Dynamic ¹¹C-Phenytoin PET Studies.

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Pharmacokinetics

Background:

• Dynamic Positron Emission Tomography (PET) enables quantitative analysis of radiotracer kinetics.
• Accurate generation of parametric images is crucial for reliable kinetic modeling in PET studies.

Purpose of the Study:

• To evaluate and compare different methods for generating quantitative parametric images from dynamic 11C-phenytoin PET studies.
• To assess the accuracy and variability of parametric distribution volume (V_T) and influx rate (K₁) values derived from various analytical techniques.

Main Methods:

• Acquisition of 60-min dynamic 11C-phenytoin PET studies with arterial sampling in 6 healthy subjects.
• Generation of parametric images using Logan plot analysis, basis function method, and spectral analysis.
• Comparison of parametric V_T and K₁ with nonlinear regression and determination of test-retest variability.

Main Results:

• All parametric methods showed less than 5% bias for V_T.
• Spectral analysis exhibited a 16% negative bias for K₁.
• Mean test-retest variabilities for V_T and K₁ were below 10% across all methods.
• Reducing scan duration to 45 min yielded comparable results to 60-min scans.

Conclusions:

• The basis function method demonstrated the least bias for V_T and K₁ compared to nonlinear regression.
• The basis function method achieved test-retest variabilities below 5%, even with smaller ROIs and shorter scan durations.
• This method offers a robust approach for quantitative parametric imaging in 11C-phenytoin PET studies.