Gastrointestinal 4D MRI with respiratory motion correction

Area of Science:

• Medical Imaging
• Radiation Oncology
• Gastrointestinal Physiology

Background:

• Gastrointestinal (GI) motion, including peristalsis and segmental contractions, significantly impacts organ position during radiation therapy.
• Conventional 4D-MRI techniques, designed for respiratory motion, fail to capture GI motion, leading to inaccuracies in treatment planning.
• Accurate visualization of GI motion is essential for defining internal target volumes and organs at risk.

Purpose of the Study:

• To develop and validate a novel 4D MRI method for visualizing periodic gastric motion, independent of respiratory motion.
• To assess the impact of GI motion on regional anatomical structures during MRI simulation.
• To provide a tool for improved accuracy in radiation therapy planning for abdominal cancers.

Main Methods:

• Sixty-seven dynamic contrast-enhanced (DCE)-MRI examinations were acquired using a golden-angle stack-of-stars sequence.
• A novel reconstruction method integrated respiratory motion correction and extracted a gastric motion signal from time-intensity curves.
• Breathing-corrected images were sorted by gastric phase and reconstructed into 21 distinct motion state images.

Main Results:

• The developed technique successfully reconstructed breathing-compensated image volumes, clearly showing gastric motion states without respiratory artifacts.
• The mean frequency of the gastric motion signal was determined to be 3 cycles/min (SD=0.27 cycles/min).
• The method demonstrated the ability to visualize periodic GI motion distinctly.

Conclusions:

• The presented GI 4D MRI technique enables visualization of periodic gastrointestinal motion, overcoming limitations of conventional methods.
• This technique holds potential for enhancing internal target volume definition and organ at risk delineation in radiation therapy planning.
• GI 4D MRI can support the development of motion tracking algorithms for real-time MR-guided radiation therapy.