List mode-driven cardiac and respiratory gating in PET

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Cardiovascular Imaging

Background:

• Motion artifacts in Positron Emission Tomography (PET) imaging, particularly from cardiac and respiratory movements, degrade image quality and can lead to misinterpretations.
• Traditional gating methods, such as electrocardiography (ECG) for cardiac gating and video monitoring for respiratory gating, are used to mitigate these motion effects.

Purpose of the Study:

• To evaluate and compare different cardiac and respiratory gating methods for PET imaging.
• To assess the efficacy of methods based on inherent list mode data versus external signals (ECG, video).

Main Methods:

• Three gating methods were evaluated in 29 coronary artery disease patients undergoing list mode PET scans: ECG/video-based gating, a sensitivity-based list mode method, and a center-of-mass based list mode method.
• Gating accuracy was assessed using measures like left ventricular wall displacement and ejection fraction.

Main Results:

• All evaluated methods successfully reduced motion-induced blurring in PET images.
• The center-of-mass list mode method showed significantly greater left ventricular wall displacements compared to the sensitivity method.
• List mode-based cardiac gating using the center-of-mass method correlated well (r=0.95) with ECG-based gating for ejection fraction in patients with high (18)F-FDG uptake.

Conclusions:

• Analyzing PET list mode data frame-by-frame is a valid approach for obtaining gating signals.
• This internal list mode analysis provides an effective alternative to external gating signals like ECG and video tracking for reducing motion artifacts in PET scans.