Abstract

Purpose: To extend the KomaMRI simulator with motion capabilities that enable the simulation of both simple, parametrizable motion patterns and arbitrarily complex spin trajectories. Additionally, we introduce a novel file format for storing and sharing dynamic digital phantoms. Methods: The existing Phantom structure in KomaMRI has been extended with a new motion field, which preserves support for static phantoms and introduces the capability to define dynamic models, composed of either a single or an arbitrary set of elementary motions. Each motion entry is composed of an action, a time curve, and a spin span, allowing for modular definition and full parameter independence across motion components. An HDF5-based phantom file format has been defined, along with two I/O functions within the simulator. Motion-related MRI experiments have been conducted for both illustrative and comparative evaluation. Results: Illustrative experiments reveal motion-related effects commonly observed in real MRI, such as time of flight and phase contrast. Comparative evaluations show strong qualitative and quantitative agreement with results reported by other simulation tools and with at least a three-fold reduction in computation time. Conclusions: The proposed extension adds flexible motion modeling and simulation capabilities to KomaMRI. The proposed new functions allow for accurate and high temporal and spatial resolution, only limited by computational cost. © 2025 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.