Automatic calibration of trigger delay time for cardiac MRI

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Radiology

Background:

• Accurate cardiac imaging relies on precise trigger delay to capture specific cardiac phases.
• Traditional methods for trigger delay calibration can be time-consuming and may require breath-holding.
• Developing rapid, free-breathing (FB) calibration techniques is crucial for improving patient comfort and throughput in cardiac MRI.

Purpose of the Study:

• To develop and validate a rapid, automated method for identifying the cardiac rest period using free-breathing (FB) calibration.
• To determine the optimal trigger delay for cardiac imaging.
• To assess the accuracy and reproducibility of a real-time trigger delay calibration system.

Main Methods:

• A standard deviation (SD) method was employed on multiphase cine cardiac images to rapidly identify cardiac quiescent phases.
• Low-resolution FB cine images were evaluated for rapid calibration scanning.
• A real-time feedback system integrated the FB calibration for T1-weighted, short-axis imaging.

Main Results:

• The SD algorithm accurately identified the cardiac rest period, showing strong correlation with a reference method (R² = 0.68-0.84).
• Real-time end-systolic trigger delay resulted in significantly smaller left ventricular blood pool areas compared to adjacent time points (p < 0.01).
• The low-resolution FB imaging method demonstrated reproducibility for calibration scanning (average SD of trigger times, 16-39 ms).

Conclusions:

• The rapid FB calibration scanning combined with a real-time feedback system accurately adjusts trigger delay for cardiac imaging.
• This real-time trigger delay calibration method is rapid, reliable, and facilitates routine cardiac MRI examinations.
• The developed technique enhances the efficiency and accuracy of cardiac imaging protocols.