Comparison between a dual-time-window protocol and other simplified protocols for dynamic total-body ¹⁸F-FDG PET...

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Pharmacokinetics

Background:

• Dynamic positron emission tomography (PET) imaging often requires invasive blood sampling and long scan durations.
• Total-body PET scanners like uEXPLORER offer enhanced sensitivity and whole-body coverage, potentially overcoming these limitations.

Purpose of the Study:

• To implement and evaluate a dual-time-window (DTW) protocol for dynamic total-body ¹⁸F-FDG PET scans.
• To compare the DTW protocol's quantification accuracy with other simplified methods for total-body FDG imaging.

Main Methods:

• A DTW protocol was simulated on 28 patient scans from a 60-min dynamic uEXPLORER PET/CT scan.
• Nonlinear fitting estimated missing data, and a hybrid approach provided the input function.
• Kinetic parameters (K_i, K₁) were quantified in the cerebral cortex, muscle, and tumor lesions using an irreversible two-tissue compartment model.

Main Results:

• The DTW protocol (10-min early, 5-min late scan) showed high consistency with a 60-min reference scan for K_i (correlations 0.971-0.990) and K₁ (correlations 0.820-0.975).
• DTW exhibited the lowest bias for K_i compared to other methods (Patlak, FUR, SUV).
• Whole-body parametric images generated by DTW were consistent with reference images.

Conclusions:

• The DTW protocol enables accurate kinetic quantification (K_i, K₁) and acceptable visual performance in dynamic total-body ¹⁸F-FDG PET scans within a reduced 15-minute duration.
• Consideration of the trade-off between accuracy and feasibility is crucial for practical implementation.
• DTW is recommended for tasks requiring reliable visual assessment or multi-parameter quantification; fractional uptake ratio (FUR) with a hybrid input function is a feasible alternative for regional metabolic rate quantification.