Rapid Visualization of Valves and Myocardium Using Volume Rendering of 3D Cardiac MRI, 4D Cine, and 4D Flow Images

Purpose To develop a volume rendering method to visualize myocardial structures and blood flow using three-dimensional (3D), four-dimensional (4D) cine, and 4D flow cardiac MRI. Materials and Methods In this retrospective study, custom transfer functions for volume rendering and novel dense streamline-based 4D flow visualizations were developed and implemented in 3D Slicer, an open-source image computing platform. These techniques were applied to the cardiac MRI studies (April 2023 to January 2025) of four pediatric patients with congenital heart disease to inform comprehension of complex anatomy and to guide surgical repair. Results Applications are demonstrated in four patients (mean age, 4.5 years ± 1.1 [SD]; three female, one male), including integration into interventional planning workflows. Cardiac MRI enabled rapid and dynamic 3D and 4D visualization of the myocardium and valves in less than 1 second, with image refinement completed in less than 3 minutes. The integration of tissue rendering with 4D flow visualization allowed the simultaneous depiction of valve dynamics, regurgitation, and stenosis. Conclusion Volume rendering of the myocardium and cardiac valves in MRI studies enables rapid, dynamic visualization and can be feasibly applied in clinical settings. Integration with 4D flow visualization may improve the understanding of valve dysfunction and support procedural planning. <b>Keywords:</b> Pediatrics, MR Imaging, Heart, Valves <i>Supplemental material is available for this article.</i> © RSNA, 2026.