[Effects of CT-based Attenuation Correction on PET Images Using Data-driven Respiratory Gating]

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiology

Background:

• Accurate attenuation correction is crucial for quantitative PET/CT imaging.
• Respiratory motion can cause misalignment between PET and CT data, affecting image quality.
• Deviceless, data-driven respiratory gating (DDG) offers a novel approach to motion correction.

Purpose of the Study:

• To validate the impact of PET/CT misalignment at different respiratory phases using DDG.
• To assess the accuracy of CT-based attenuation correction with DDG under various respiratory conditions.

Main Methods:

• Simulated a lung lesion in a phantom with hot spheres.
• Acquired PET/CT data during simulated respiratory motion.
• Applied DDG and CT-based attenuation correction using inspiratory, stationary, and expiratory CT phases.
• Analyzed image quality using Normalized Mean Square Error (NMSE), recovery coefficients (RC), and volume measurements.

Main Results:

• NMSE was minimized, and recovery coefficients (RCmax <1.0, RCmean ≈1.0) were optimal when using expiratory phase CT for correction.
• Image volume accuracy was significantly affected by sphere size and CT/PET alignment.
• Expiratory phase correction demonstrated superior performance compared to inspiratory or stationary phases.

Conclusions:

• The expiratory phase is recommended for CT-based attenuation correction when using DDG in PET/CT imaging.
• Inspiratory phase CT data should be avoided for DDG-based PET/CT correction.
• Optimizing respiratory gating is essential for accurate quantitative PET/CT analysis, particularly for lung lesions.