Free‐Breathing Dynamic, Regularized, Adaptive Cluster Optimization ( DRACO ) Cine Cardiac MRI in Atrial Fibrillation

BACKGROUND: Existing strategies for free-breathing cine cardiac MR, including real-time imaging, struggle with complex arrhythmias such as atrial fibrillation (AF). Dynamic regularized adaptive clustering optimization (DRACO) has been proposed to generate high-quality and quantifiable breath-held cine images for patients in AF. PURPOSE: To tailor DRACO for free-breathing and evaluate its potential to simultaneously handle cardiac and respiratory motion. STUDY TYPE: Prospective. SUBJECTS: 10 sinus rhythm (10 males), 20 AF (18 males). FIELD STRENGTH/SEQUENCE: 3.0 T, balanced steady-state free precession (bSSFP) with sorted golden-step, ECG-gated segmented cine, and real-time. ASSESSMENT: Patients were imaged using the golden-step sequence under breath-held and free-breathing conditions, and the reference bSSFP cine sequence. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), edge sharpness, and image quality (4-point Likert scale) were assessed. STATISTICAL TESTS: Paired t-test, Friedman test, regression analysis, Fleiss' Kappa. Significance level p < 0.05. RESULTS: The SNR and CNR values of DRACO images showed no significant differences between breath-held and free-breathing conditions in both sinus rhythm (SNR p = 0.53; CNR p = 0.87) and in AF (SNR p = 0.56; CNR p = 0.55). Image sharpness was not significantly different between breath-held and free-breathing in both sinus rhythm (p = 0.24) and AF (p = 0.79). In AF patients, breath-held DRACO and free-breathing DRACO had significantly higher image quality scores than real-time cine. In sinus rhythm patients, there was no significant difference (p = 0.13) between breath-held or free-breathing DRACO and segmented cine. Despite significant within-patient ejection fraction (EF) differences between breath-held versus free-breathing in 80% of sinus rhythm and 70% of AF patients, the average EF between breath-held versus free-breathing DRACO showed high correlation (sinus rhythm R2 = 0.71; AF R2 = 0.71), demonstrating DRACO's robustness to motion variation. DATA CONCLUSION: DRACO is robust to respiratory motion and AF-related irregular cardiac motion. It enables high-quality cine image generation in both regular and irregular cardiac motion, with or without breath holding. TECHNICAL EFFICACY: Stage 2. Cine cardiac MRI is a technique that captures the motion of a beating heart and provides information about structure and function. Most existing methods can handle motion that occurs at repeatable intervals; however, they are less effective when the interval duration becomes irregular or unpredictable. Dynamic, Regularized, Adaptive Cluster Optimization (DRACO) was developed to capture irregular cardiac motion in the absence of respiratory motion. We demonstrate DRACO's capability for simultaneously capturing irregular cardiac motion affected by respiratory motion. We showed that DRACO can produce high‐quality cine images in cases of regular and irregular heart motion, with or without respiratory motion.