A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging

Area of Science:

• Medical Imaging
• Radiation Oncology
• Computational Anatomy

Background:

• Accurate visualization of moving tumors during radiation therapy is crucial for effective treatment delivery.
• Current on-board imaging techniques may lack the necessary spatial and temporal resolution for precise targeting of internal organ motion.

Purpose of the Study:

• To develop and validate a technique for generating on-board volumetric cine-magnetic resonance imaging (VC-MRI).
• To enable real-time 3D MRI reconstruction using patient prior images, motion modeling, and on-board 2D cine MRI.

Main Methods:

• Utilized 4D MRI data for patient prior images and extracted respiratory deformation patterns via principal-component analysis.
• Modeled on-board VC-MRI as a deformation of the prior MRI, with coefficients solved using on-board 2D cine MRI data.
• Evaluated the technique using digital XCAT simulations and real patient data, assessing accuracy with volume-percent-difference (VPD), center-of-mass-shift (COMS), and tracking errors.

Main Results:

• Estimated VC-MRI showed significantly fewer differences compared to ground-truth than prior images alone.
• Achieved less than 6% error in normalized profile agreement for both simulated and patient data.
• Demonstrated average lesion volume VPD of 8.43 ± 1.52% and COMS of 0.93 ± 0.58 mm in XCAT simulations.
• Reported average tracking errors of less than 2 mm for patient data, with robustness against noise up to SNR = 20.

Conclusions:

• The developed technique is feasible for generating real-time VC-MRI.
• This method shows promise for on-board localization of moving targets in radiation therapy.