Rhythm Classification and Visualization in Real Time Cardiac Magnetic Resonance Imaging

Atrial fibrillation (AF) is the most common chronic cardiac arrhythmia. Its irregularity and rapidity of heartbeats can cause significant symptoms, impair heart function, and increase the risk of stroke and heart failure. Imaging of AF advanced recently with real-time magnetic resonance (rtCMR) acquisitions during free breathing. Compared with the imaging of standard cardiac magnetic resonance (CMR), rtCMR imaging records all cardiac cycles without averaging and is better suited to visualize cardiac cycles. We developed tools to automatically visualize the main heart motion, track and capture all arrhythmic and normal cardiac cycles in rtCMR, and find means of classifying rhythms. 38 volunteers were included in the study, 20 of them with history of AF or other cardiac disease. The visualization revealed variation in heartbeat length, filling time, and ejection fraction. The case studies show how the new measurements distinguish among cardiac motion in sinus rhythm, respiratory sinus arrhythmia, AF, and heart failure (HF) accompanying AF. These tools and results may provide radiologists with a method to monitor irregular heartbeats, and complement AF diagnosis by electrocardiography.