Real-time CMR Fourier Analysis for Temporospatial Characterization of Ventricular Wall Motion in Health and Disease

Background Cardiovascular magnetic resonance (CMR) has been largely dependent on retrospective cine for image acquisition. Real-time imaging, although inferior in image quality to retrospective cine, is advantageous in examining temporospatial behaviors of cardiac motion over a series of sequential cardiac cycles. The presented work is a proof-of-concept of assessing cardiac function quantitatively with novel temporospatial indices in real-time CMR. Methods Fourier analysis was introduced for temporospatial characterization of real-time CMR signals arising from ventricular wall motion. Two quantitative indices, temporal periodicity and spatial coherence, were provided for function assessment in the left ventricle (LV) and right ventricle (RV). We prospectively investigated these temporospatial indices in a CMR study with healthy volunteers and heart failure (HF) patients. Results Real-time images were collected and analyzed in 12 healthy volunteers during exercise and at rest, and also in 12 HF patients at rest. The statistics indicated that the healthy volunteers presented an increase of temporal periodicity due to ventricular response to exercise (resting-state 0.24 ± 0.037 vs. exercising-state 0.31 ± 0.040 in LV; resting-state 0.18 ± 0.030 vs. exercising-state 0.25 ± 0.038 in RV; P < 0.001 for both). The HF patients gave lower temporal periodicity (0.14 ± 0.021 for LV; 0.10 ± 0.014 for RV; P < 0.001 for both) than that in the healthy volunteers. The spatial coherence of LV and RV wall motion was also lower in the HF patients than that in the healthy volunteers (0.38 ± 0.040 vs 0.52 ± 0.039 for LV; 0.35 ± 0.035 vs. 0.50 ± 0.036 for RV; P < 0.001 for both). Both temporal periodicity and spatial coherence were found to be correlated to end-systolic volume (ESV) and ejection-fraction (EF) (R > 0.6, P < 0.001). However, the HF patients and healthy volunteers were well differentiated in the scatter plots of spatial coherence and temporal periodicity while they were mixed in those of ESV and EF. Conclusions Real-time CMR Fourier analysis enables a new approach to quantitative assessment of cardiac function with temporal periodicity and spatial coherence. The temporospatial characterization of real-time CMR images has the potential for intricate analysis of ventricular wall motion beyond conventional methods.