Precision assessment of bowel motion quantification using 3D cine-MRI for radiotherapy

Area of Science:

• Radiotherapy and Oncology
• Medical Imaging
• Gastroenterology

Background:

• Pelvic and abdominal radiotherapy pose a risk of bowel toxicity.
• Accurate quantification of bowel motion using MRI can help understand toxicity development.
• Current MRI acquisition times are a limitation.

Purpose of the Study:

• To retrospectively evaluate the precision of bowel motion quantification using 3D cine-MRI.
• To estimate the minimum MRI acquisition time required for precise measurements.

Main Methods:

• Analyzed 10-minute 3D cine-MRI scans (160 dynamics) from 22 gynecologic cancer patients.
• Used deformable registration to generate deformation vector fields (DVFs).
• Quantified median (VL50) and high (VL95) bowel motion, assessing precision across 2.5, 5.0, and 7.5-minute scan times.

Main Results:

• A 7.5-minute scan time achieved <0.5 mm variation in 100% (VL50) and 95% (VL95) of subsets.
• Shorter scan times (5.0 and 2.5 min) showed reduced precision.
• Bowel motion ranged from 0.6-3.5 mm (VL50) and 2.3-9.0 mm (VL95) across patients.

Conclusions:

• 3D cine-MRI can quantify bowel loop motion with high confidence (95%-100%).
• A precision of 0.5 mm variation or less is achievable with a 7.5-minute scan time.
• Reduced MRI acquisition time is feasible for precise bowel motion assessment in radiotherapy.