Improved correction for the tissue fraction effect in lung PET/CT imaging

Area of Science:

• Nuclear Medicine
• Pulmonary Imaging
• Medical Physics

Background:

• Positron Emission Tomography (PET) techniques are increasingly used for pulmonary disorder imaging.
• Previous studies highlighted the 'tissue fraction effect' (TFE) from lung air content impacting static PET/CT.
• The TFE's influence on dynamic imaging and the contribution of blood content remained less explored.

Purpose of the Study:

• To extend the understanding of the TFE in pulmonary PET/CT imaging.
• To investigate the impact of both air and blood components on dynamic PET imaging.
• To develop and validate correction methods for TFE in quantitative PET analysis.

Main Methods:

• Utilized CT imaging and PET kinetic modeling in six idiopathic pulmonary fibrosis patients.
• Determined fractional air and blood voxel volumes.
• Calculated correction factors for Standardized Uptake Value (SUV) and kinetic parameters (K1, Ki).

Main Results:

• The TFE significantly affects static (SUV) and dynamic (K1, Ki) PET parameters, with both air and blood contributing substantially to errors.
• Uncorrected errors ranged from 34-80% (best case) and 29-96% (worst case).
• Air and blood correction reversed the apparent uptake differences in fibrotic versus normal lung tissue, demonstrating improved accuracy.

Conclusions:

• The TFE, influenced by both air and blood, significantly impacts quantitative accuracy in pulmonary PET/CT.
• Proposed correction methods are essential for reliable interpretation of static and dynamic PET images.
• Failure to correct for TFE can lead to misinterpretation of disease extent and severity in pulmonary disorders.