Mitral valve flow and myocardial motion assessed with dual-echo dual-velocity cardiac MRI

Purpose: To develop a dual-echo phase-contrast (DEPC) MRI approach with which each echo is acquired by using a different velocity sensitivity within one repetition time (TR) and demonstrate the feasibility of this approach to measure transmitral blood flow (E) and myocardial tissue (E_m) velocities. Materials and Methods: The flow across tubes of known diameter was measured by using the proposed DEPC method and compared with flowmeter measurements and theoretic predictions. Then, with both the DEPC MRI sequence and the conventional single-echo phase-contrast (SEPC) MRI sequence, E, E_m, and E/E_m were measured in six healthy volunteers (mean age, 49 years ± 13 [standard deviation]) and eight patients (mean age, 54 years ± 15) being evaluated for cardiac disease. Differences between the DEPC and conventional SEPC MRI methods were assessed by percent error, Pearson correlation, and Bland-Altman analyses. Results: Velocities measured in vitro and in vivo by using the SEPC and DEPC MRI approaches were well correlated (r² > 0.97), with negligible bias (<0.5 cm/sec) and comparable velocity-to-noise ratios. Imaging times were approximately 19% shorter with the DEPC method (TR, 5.7 msec) than with the SEPC method (TR, 2.8 msec ± 4.2) (P < .05). Conclusion: The proposed DEPC method was sensitive to two velocity regimes within a single TR, resulting in a shorter imaging time compared with the imaging time in conventional SEPC MRI. Preliminary human study results suggest the feasibility of using this approach to estimate E/E_m.