WE-G-213CD-04: A Triggering System to Guide 4DMRI Image Acquisition

Area of Science:

• Medical Imaging
• Radiotherapy
• Biomedical Engineering

Background:

• Accurate tracking of abdominal tumor motion during radiotherapy is crucial for treatment planning.
• Four-dimensional Magnetic Resonance Imaging (4DMRI) is a promising technique for motion tracking.
• Previous 4DMRI techniques often utilized T1 or T2/T1 weighting, limiting tumor-tissue contrast.

Purpose of the Study:

• To develop a practical triggering system for prospective image acquisition in 4DMRI.
• To guide 4DMRI acquisition based on pre-selected respiratory amplitudes for abdominal tumor motion tracking.
• To enable T2-weighted 4DMRI for improved tumor visualization in radiotherapy planning.

Main Methods:

• A novel triggering system was developed, comprising preparation and acquisition stages.
• Respiration is monitored using an external belt, dividing the respiratory cycle into N states.
• Each respiratory state triggers the acquisition of a single slice, forming a complete 4DMRI dataset.

Main Results:

• The system successfully triggered image acquisition at expected physiological points.
• Four T2-weighted images demonstrated the tracking of liver motion across four respiratory states.
• The proof-of-principle was validated on a healthy subject using a clinical 1.5T MRI scanner.

Conclusions:

• The developed system prospectively guides 4DMRI acquisition for T2-weighted imaging.
• This T2-weighted 4DMRI provides superior tumor-tissue contrast compared to prior methods.
• This represents the first report of pure T2-weighted 4DMRI for tracking respiration-induced abdominal motion.