Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: a feasibility study

Area of Science:

• Medical Imaging
• Radiation Oncology
• Biomedical Engineering

Background:

• Four-dimensional computed tomography (4D-CT) is crucial for radiation therapy planning, assessing breathing motion to define safety margins.
• However, 4D-CT suffers from poor soft-tissue contrast and high radiation doses.
• This necessitates the development of advanced imaging techniques for motion assessment.

Purpose of the Study:

• To develop and validate a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique.
• To overcome the limitations of 4D-CT in soft-tissue contrast and radiation dose.
• To provide accurate patient-specific breathing motion assessment for radiation therapy.

Main Methods:

• A novel 4D-MRI technique was developed using fast 2D cine-MR imaging.
• Images were retrospectively sorted by respiratory phase using body area (BA) as an internal surrogate.
• Validation involved comparison with 4D-CT and Real-time position management (RPM) systems in patients and phantoms.

Main Results:

• The BA surrogate demonstrated high correlation with RPM for phase determination (correlation coefficient: 0.93).
• 4D-MRI accurately depicted motion in phantoms with minimal artifacts and excellent agreement in motion amplitude.
• Human subject studies showed clear visualization of respiratory motion in internal organs.

Conclusions:

• The developed retrospective 4D-MRI technique using body area as a respiratory surrogate is feasible.
• This technique offers a promising alternative to 4D-CT for radiation therapy motion assessment.
• Further clinical implementation is warranted based on preliminary findings.