Cardiac gating with a pulse oximeter for dual-energy imaging

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Radiology

Background:

• Cardiac motion artifacts degrade the quality of dual-energy (DE) imaging.
• Current gating methods, often relying on electrocardiograms, can be complex and costly.
• Reducing motion artifacts is crucial for accurate DE imaging interpretation.

Purpose of the Study:

• To develop and evaluate a prototype cardiac gating system for DE imaging using a fingertip pulse oximeter.
• To minimize heart misalignment and cardiac motion artifacts by acquiring images during diastole.
• To assess the accuracy, precision, and effectiveness of the developed gating system.

Main Methods:

• A fingertip pulse oximeter was used to measure the peripheral pulse waveform (plethysmogram) for cardiac gating.
• A gating method was developed to accommodate system and physiological delays, calculating an implemented delay, t(imp).
• The system was modeled with two heart rate (HR) regimes and evaluated for trigger coincidence accuracy and artifact reduction.

Main Results:

• Initial implementation achieved 85% accuracy in diastole-trigger coincidence.
• An improved HR estimation method enhanced trigger accuracy to 100% with better precision.
• Human observer tests showed a statistically significant reduction in cardiac motion artifact magnitude with successful gating (p < 0.001).

Conclusions:

• The developed cardiac gating system effectively reduces cardiac motion artifacts in DE imaging.
• Utilizing a pulse oximeter offers a potentially simpler and more cost-effective alternative to electrocardiogram-based gating.
• Successful diastolic gating significantly improves DE image quality, with residual artifacts mainly due to gross patient motion.