Integrated Magnetic Resonance Imaging for Radiation Therapy Applications

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Introduction*** Radiation therapy relies heavily on imaging information for treatment planning, dose prediction, and radiation delivery. The soft tissue contrast and imaging flexibility provided by MRI can greatly impact this process. The long-term goal of this program is an integrated MRI approach to robust anatomical and physiological imaging for radiation therapy. Our research will provide improved contrast to clinicians for accurate contouring, tissue type information for dose calculations, and robust physiological measures to guide treatment decisions, and further enable MRI-based planning.***Aims***1. Develop an optimized structural MR imaging approach for tailored in vivo imaging of tissue anatomy for RT planning, based on a multi-echo gradient echo (MGRE) sequence for T1- and T2*-weighted imaging, and compare the derived T2* contrast to conventional T2 contrast for lesion and organ delineation***2. Design, implement and validate an MRI approach to robustly delineate the major tissue categories (soft tissue, bone, air) based on magnetic susceptibility mapping, to overcome the limitations of conventional MRI in areas lacking water signal. ***3. Develop a practical physiological imaging method for the RT planning process using DCE MRI, with fast, robust pattern-recognition (PR)-based analysis. We will jointly design data acquisition, image reconstruction and analysis***Scientific Approach*** Volumetric multi-echo gradient echo imaging will be the foundation of this in vivo imaging approach tailored to RT treatment planning. Multi-contrast anatomical imaging will target organ delineation and lesion identification. Magnetic-susceptibility-based reconstruction of air, bone, and soft tissue information combined with tissue property assignment will be investigated as an approach to X-ray heterogeneity information for dose calculation. A practical and robust approach for contrast-enhanced perfusion MRI will be evaluated, compared to model-based perfusion metrics as a marker of tumor physiology, and evaluated for dose modulation. All components of the approach will be designed to share data and to make the entire process more efficient. The integration of our academic unit in the radiation oncology practice will be key to investigate critical aspects that can impact the planning and simulation workflow.***Novelty and Significance*** MR imaging will potentially transform RT simulation, planning, delivery, and treatment assessment for a number of cancers. The soft tissue contrast and physiological information from this MRI approach will impact RT planning, treatment decisions, and assessment. Our integrated approach will provide the necessary information for image-based RT treatment planning, and result in feasible MR-based simulation and practical follow-up imaging in the clinical RT context.**