BACKGROUNDQuantitative MRI enables the measurement of tissue-specific relaxation times such as T1, T2, and T1ρ, allowing the assessment of myocardial fibrosis or edema without the need for contrast agents [1]. Magnetic Resonance Fingerprinting (MRF) is a promising approach for clinical application, as it allows simultaneous quantification of multiple parameters within reduced scan times [2,3]. However, reproducibility between different vendors, platforms, and field strengths remains limited due to non-standardized acquisition and reconstruction pipelines. To overcome these limitations, we developed OpenMRF - a vendor-agnostic, open-source framework for the design, simulation, and reconstruction of cardiac MRF (cMRF) sequences, enabling standardized and reproducible multi-center studies.
METHODSOpenMRF builds on the Pulseq format for vendor-independent MRI sequence programming [4] and unifies the entire cMRF workflow, from sequence definition to image reconstruction. The main modules include: (1) flexible readouts supporting spiral, radial, and rosette trajectories (2) standardized T1, T2, and T1ρ preparations (3) automated Bloch simulation for accurate dictionary generation (4) reconstruction using an iterative low-rank algorithm.
Validation was performed using the NIST phantom on multiple Siemens scanners at 0.55T, 1.5T, and 3T. The unified T1–T2–T1ρ cMRF protocol was evaluated in a multi-site study. In-vivo feasibility was further demonstrated in healthy subjects.
RESULTSPhantom measurements (Fig. 1) showed excellent agreement with gold-standard references, with minor deviations of +3.1% (T1) and -1.2% (T2). T1ρ values obtained from MRF were slightly lower compared to conventional mapping (-7.4%). Parameter maps demonstrated high inter-site reproducibility. In-vivo experiments confirmed robust performance, showing clear delineation of the left-ventricular myocardium and consistent quantitative values within the expected physiological range (Fig. 2).
DISCUSSION & CONCLUSIONOpenMRF enables reproducible and standardized cardiac tissue characterization using identical open-source Pulseq sequences. By integrating standardized preparations, Bloch simulations, and low-rank reconstruction, the framework bridges technical sequence development and clinical translation. The presented results demonstrate that quantitative cardiac MRI can be performed in a harmonized and vendor-independent manner, providing reliable relaxation time maps. The long-term goal is to link functional and quantitative cardiac imaging within a unified cMRF approach, enabling the comprehensive assessment of both structural and functional myocardial changes in a single examination.
The OpenMRF project establishes a harmonized and fully transparent workflow for quantitative cardiac MRI. Its reproducibility across scanners, field strengths, and research sites provides a solid foundation for future multi-center validation of native myocardial tissue characterization.
[1] Christodoulou A et al. doi: 10.1016/j.jocmr.2024.100997 [2] Ma D et al. doi: 10.1038/nature11971 [3] Hamilton JI et al. doi: 10.1002/mrm.26216 [4] Layton KJ et al. doi: 10.1002/mrm.26235
