Improving image reconstruction to quantify dynamic whole-body PET/CT: Q.Clear versus OSEM

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiochemistry

Background:

• Dynamic whole-body PET/CT protocols assess 18F-FDG uptake rates but face challenges with noise in Short-Axis Field-of-View (SAFOV) systems.
• High noise levels necessitate increased 18F-FDG activity, leading to higher patient radiation doses.
• Bayesian penalized-likelihood reconstruction (e.g., Q.Clear) is a promising technique for noise reduction in PET imaging.

Purpose of the Study:

• To investigate the impact of Bayesian penalized-likelihood reconstruction (Q.Clear) on dynamic whole-body 18F-FDG PET/CT quantification.
• To compare image noise and the precision of 18F-FDG uptake rate (K) values obtained using Q.Clear versus standard OSEM reconstruction.
• To evaluate the influence of lesion size and K values on the performance of different reconstruction methods.

Main Methods:

• Dynamic whole-body 18F-FDG PET/CT data from healthy volunteers and a lung cancer patient were reconstructed using Q.Clear and OSEM.
• Image noise was quantified in time-activity curves (TACs) from various tissues and a lung lesion.
• 18F-FDG uptake rates (K) were calculated using Patlak analysis, with bootstrapping used to assess bias and precision.

Main Results:

• Q.Clear demonstrated 40-55% lower noise levels across all tissue types compared to OSEM (p < 0.05).
• No systematic bias in K values was observed for either method.
• Q.Clear provided superior precision for K values in small volumes of interest (0.56 cm³) across all tissues, particularly for low K values (p < 0.05).

Conclusions:

• Q.Clear reconstruction enhances the precision of 18F-FDG uptake rate (K) quantification in dynamic whole-body PET/CT.
• The improved precision is particularly notable for small K values and smaller volumes of interest, crucial for oncology applications.
• Q.Clear shows potential for improved detection of small lesion metabolic activity and enables reduced administered 18F-FDG activity, thus lowering patient radiation dose.