Noninvasive measurement of pressure gradient across a coronary stenosis using phase contrast (PC)-MRI: A feasibility study

Purpose: To investigate the feasibility of blood pressure difference measurement, ΔP, across the coronary artery using phase contrast (PC)-MRI for potential noninvasive assessment of the functional significance of coronary artery stenosis. Methods: Three-directional velocities in the coronary arteries acquired using 2D-PC-MRI were used with the Navier-Stokes equations to derive ΔP. Repeat phantom studies were performed to assess the reproducibility of flow velocity and ΔP. ΔP derived using PC-MRI (ΔP_MR) and that obtained using pressure transducer (ΔP_PT) were compared. Reproducibility of coronary flow velocity was assessed in healthy controls (n = 11). Patients with suspected coronary artery disease (n = 6) were studied to evaluate the feasibility of ΔP_MR measurement across a coronary stenosis. Results: Phantom: Good overall reproducibility of flow velocity and ΔP measurements and excellent correlation (ΔP_MR vs ΔP_PT) was observed: intraclass correlation (ICC) of 0.95(V_z), 0.72(V_x), 0.73(V_y), and 0.87(ΔP_MR) and R² = 0.94, respectively. Human: Good reproducibility of coronary flow velocity was observed: ICC of 0.94/0.95(V_z), 0.76/0.74(V_x), and 0.80/0.77(V_y) at cardiac phase 1/2. Significant (p = 0.025) increase in ΔP_MR was observed in patients (6.40 ± 4.43 mmHg) versus controls (0.70 ± 0.57 mmHg). Conclusion: ΔP_MR in the coronary arteries is feasible. Upon further validation using the invasive measure, ΔP_MR has the potential for noninvasive assessment of coronary artery stenosis. Magn Reson Med 77:529–537, 2017.