Noninvasive quantification of nonhuman primate dynamic ¹⁸F-FDG PET imaging

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Pharmacokinetics

Background:

• Dynamic 18F-FDG PET imaging quantifies the uptake rate constant (Ki) using the plasma input function (PIF).
• Accurate PIF determination typically requires extensive arterial blood sampling, limiting practical application.
• The Patlak plot is a standard graphical analysis for estimating Ki in a model-independent manner.

Purpose of the Study:

• To evaluate a Patlak plot-based optimization strategy for estimating PIF with reduced blood sampling in dynamic 18F-FDG PET.
• To assess the feasibility of noninvasive quantification in non-human primate brain imaging.
• To explore potential for translation to human studies.

Main Methods:

• Collected dynamic 18F-FDG PET scans (60 min) with arterial blood sampling in eight rhesus monkeys.
• Determined measured PIF (mPIF) from arterial blood samples and generated regional time activity curves (TACs).
• Developed population-based PIF (pPIF) using interpolation/extrapolation with optimized sampling schemes and validated against mPIF using leave-two-out cross-validation.

Main Results:

• Optimal sampling schemes with 1 to 4 blood samples showed high correlations (R² ≥ 0.974) between Ki estimates from pPIF and mPIF.
• Ki estimates using pPIF with 4 samples were nearly identical to those from mPIF (R² = 0.993).
• The optimized approach demonstrated reliability in estimating PIF for non-human primate dynamic 18F-FDG PET.

Conclusions:

• A Patlak plot-based optimization approach effectively estimates PIF with reduced blood sampling for dynamic 18F-FDG PET.
• This method offers a reliable, noninvasive quantification strategy for non-human primate studies.
• The approach holds promise for future translational studies in humans.