Value CMR: Towards a Comprehensive, Rapid, Cost-Effective Cardiovascular Magnetic Resonance Imaging
AbstractCMR is considered the gold standard for measuring heart function, including cardiac volumes and mass. Further, in a single CMR exam, information about cardiac function, structure, tissue composition, and blood flow could be obtained. Nevertheless, CMR is underutilized due to long scanning times, the need for multiple breath-holds, use of a contrast agent, and relatively higher cost compared to echocardiography.In this study, we propose a rapid CMR exam based on recent developments in imaging sequences. The proposed exam is both rapid and provides comprehensive cardiovascular information without the need for a contrast agent or multiple breath-holds. The developed exam includes advanced sequences for evaluating global and regional cardiac functions, myocardial tissue characterization, and flow hemodynamics in the heart, valves, and large vessels. Time-consuming conventional sequences have been replaced by advanced sequences, which resulted in reducing scan time from > 1 hour with conventional CMR exam to <20 minutes with the proposed rapid CMR exam. Specifically, conventional two-dimensional (2D) cine and phase-contrast (PC) sequences have been replaced by optimized three-dimensional (3D)-cine and four-dimensional (4D)-flow sequences, respectively. Compared to 2D cine imaging that requires 12-16 separate breath-holds, the implemented 3D-cine sequence allows for whole heart coverage in 1-2 breath-holds; thus, reducing scan time by 80-90%. Similarly, compared to 2D PC flow imaging that requires multiple breath-holds and the presence of an experienced cardiac operator for precise prescription of the imaging planes, the implemented 4D-flow sequence allows for whole-chest coverage in ∼10-minute, free-breathing acquisition without the need for a navigator echo, which makes scan time independent of the patient’s breathing pattern. Furthermore, conventional myocardial tagging has been replaced by the fast strain-encoding (SENC) sequence, which reduces scan time from one slice per breath-hold to only one slice per heartbeat (∼1 second). Finally, T1 and T2 mapping sequences are included in this proposed exam, which allow for myocardial tissue characterization without the need for contrast. The proposed rapid exam has been tested on volunteers and measurements showed good agreement with those from conventional sequences despite the significant reduction in scan time.In conclusion, we propose a rapid, contrast-free, and comprehensive cardiovascular exam that does not require repeated breath-holds or a cardiac experienced operator to run the exam, which would result in improving cost effectiveness of CMR and increasing its adoption in clinical practice.
