Non-invasive mapping of turbulence on relative pressure fields – extending full-field estimators using Reynolds stress imaging

Motivation: 4D Flow MRI with six-directional flow encoding (ICOSA6) enables e stimation of end-to-end turbulence-driven relative pressure. However, approaches to estimate complete turbulence-driven relative pressure fields remain scarce. Goal(s): To extend two state-of-the-art approaches for full-field relative pressure assessment into turbulent flows, validating against invasive data. Approach: Using a Reynolds-averaged Navier-Stokes formulation, two approaches for full-field relative pressure assessment are extended for turbulence: the Pressure-Poisson-Equation, and the Stokes-Estimator. Validation against invasive pressures is performed in an in-vitro ICOSA6 4D Flow MRI. Results: Excellent performance is reported for both methods across various stenotic valve configurations, with specific improvement in comparison to methods overlooking turbulent flows. Impact: Using a theoretical Reynolds decomposition of velocity and pressure and leveraging Reynolds stress imaging through ICOSA6 4D Flow MRI, we show how spatial mapping of turbulent relative pressure fields is achievable, opening for detailed non-invasive assessment of turbulent hemodynamic behavior.