MyoFold: Joint myocardial tissue composition and wall motion quantification via a highly folded sequence

Purpose: This study aims to develop and evaluate a novel cardiovascular MR sequence, MyoFold, designed for the simultaneous quantifications of myocardial tissue composition and wall motion. Methods: MyoFold is designed as a 2D single breathing-holding sequence, integrating joint T₁/T₂ mapping and cine imaging. The sequence uses a 2-fold accelerated balanced SSFP (bSSFP) for data readout and incorporates electrocardiogram synchronization to align with the cardiac cycle. MyoFold initially acquires six single-shot inversion-recovery images, completed during the diastole of six successive heartbeats. T₂ preparation (T₂-prep) is applied to introduce T₂ weightings for the last three images. Subsequently, over the following six heartbeats, segmented bSSFP is performed for the movie of the entire cardiac cycle, synchronized with an electrocardiogram. A neural network trained using numerical simulations of MyoFold is used for T₁ and T₂ calculations. MyoFold was validated through phantom and in vivo experiments, with comparisons made against MOLLI, SASHA, T₂-prep bSSFP, and the conventional cine. Results: In phantom studies, MyoFold exhibited a 10% overestimation in T₁ measurements, whereas T₂ measurements demonstrated high accuracy. In vivo experiments revealed that MyoFold T₁ had comparable accuracy to SASHA and precision similar to MOLLI. MyoFold demonstrated good agreement with T₂-prep bSSFP in myocardial T₂ measurements. No significant differences were observed in the quantification of left-ventricle wall thickness and function between MyoFold and the conventional cine. Conclusion: MyoFold presents as a rapid, simple, and multitasking approach for quantitative cardiovascular MR examinations, offering simultaneous assessment of tissue composition and wall motion. The sequence's multitasking capabilities make it a promising tool for comprehensive cardiac evaluations in clinical settings.