Inlet and outlet valve flow and regurgitant volume may be directly and reliably quantified with accelerated, volumetric phase‐contrast MRI

Abstract

Purpose To determine whether it is feasible to use solely an accelerated 4D-PC MRI acquisition to quantify net and regurgitant flow volume through each of the cardiac valves. Materials and Methods Accelerated, 4D-PC MRI examinations performed between March 2010 through June 2011 as part of routine MRI examinations for congenital, structural heart disease were retrospectively reviewed and analyzed using valve-tracking visualization and quantification algorithms developed in Java and OpenGL. Excluding patients with transposition or single ventricle physiology, a total of 34 consecutive pediatric patients (19 male, 15 female; mean age 6.9 years; age range 10 months-15 years) were identified. 4D-PC flow measurements were compared at each valve and against routine measurements from conventional cardiac MRI using Bland-Altman and Pearson correlation analysis. Results Inlet and outlet valve net flow were highly correlated between all valves (ρ=0.940–0.985). The sum of forward flow at the outlet valve and regurgitant flow at the inlet valve were consistent with volumetric displacements each ventricle (ρ=0.939–0.948). These were also highly consistent with conventional planar MRI measurements of with net flow (ρ=0.923–0.935) and regurgitant fractions (ρ=0.917–0.972) at the outlet valve and ventricular volumes (ρ=0.925–0.965). Conclusion It is possible to obtain consistent measurements of net and regurgitant blood flow across the inlet and outlet valves relying solely on accelerated 4D-PC. This may facilitate more efficient clinical quantification of valvular regurgitation.

MR phase-contrast imaging in pulmonary hypertension

“…25 Westenberg et al 93 demonstrated that the assessment of tricuspid flow and regurgitation volumes from 4D PC data with retrospective manual alignment of multiplanar reconstructed tricuspid valvular imaging planes enables more accurate quantification of tricuspid flow volume, regurgitation volume and regurgitation fraction than does the use of 2D PC imaging. Roess et al 94 and Hsiao et al 95 analyzed flow and regurgitation volumes through all cardiac valves in healthy controls and patients with diverse valvular and shunt pathologies and found highly consistent results.…”

Effects of heart valve prostheses on phase contrast flow measurements in Cardiovascular Magnetic Resonance – a phantom study

“…Due to the medical development and increasing life expectancy, the number of surgeries and interventions is expected to rise [1, 2]. Currently, surgical aortic valve replacement with biological or mechanical prostheses is the standard of care in most cases of aortic stenosis [3, 4].…”

Towards high‐resolution 4D flow MRI in the human aorta using kt‐GRAPPA and B1+ shimming at 7T

“…Although the application of kt-GRAPPA with R=5 allowed acquiring the 4D flow protocol in less than 11 minutes, other approaches may need to be explored (and potentially combined) to further accelerate data acquisition for clinical application. Such approaches could include increasing the number of coil elements to achieve higher acceleration factors (15,45), applying radial acquisitions with high undersampling factors as in PC-VIPR (16), or using compressed sensing methods (20–22). Besides the acquisition time for the 4D flow protocol also the total session time is a limiting factor: in this work a period of 2.5–3 hours was required, including the setup, tuning/matching the RF coil elements, B1+ mapping, performing calibration routines, calculating B1+ shim solutions, and acquiring the 4D flow data.…”

“…Also, non-Cartesian acquisition techniques such as PC-VIPR have been successfully applied resulting in scan times below 10 minutes (16). Further shortening of the acquisition time can be achieved by accelerating along the spatial and temporal dimension using kt-BLAST, kt-SENSE and kt-GRAPPA (17–19), or by applying compressed sensing techniques (20–22). Applying both temporal and spatial acceleration is a promising route to achieve short total acquisition time while pushing towards higher resolution.…”