Real-time Multi-Contrast 4D MRI using Motion Transfer for Low-Latency Volumetric Motion Tracking on a 1.5T MR-Linac System

Real-time multi-contrast 4D MRI is proposed by transferring motion from 4D T1-weighted images to 3D T2-weighted images and performing fast signature matching based on T1-weighted 3D radial stack-of-stars acquisitions. The proposed approach exploits the anatomical correlations between T1-weighted and T2-weighted images and fast acquisition of T1-weighted data to generate real-time multi-contrast volumetric motion information for adaptation and monitoring of radiation treatment of tumors affected by respiratory motion on an MR-Linac system. The feasibility of the proposed method was demonstrated on patients with pancreatic cancer.