4D FLOW CMR in congenital heart disease

This thesis showed that the use of a cloud-based reconstruction application
with advanced eddy currents correction, integrated with interactive
imaging evaluation tools allowed for remote visualization and interpretation
of 4D flow data and that was sufficient for gross visualization
of aortic valve regurgitation. Further, this thesis demonstrated that bulk
flow and pulmonary regurgitation can be accurately quantified using 4D
flow imaging analyzed. Peak systolic velocity over the pulmonary valve
may be underestimated. However, the measurement of peak systolic
velocity can be optimized if measured at the level of highest velocity in
the pulmonary artery. Also correlated against invasive measurements (in
an animal model), this thesis shows that aorta flow and pulmonary flow
can be accurately and simultaneously measured by 4D flow MRI.
When applied in clinical practice, 4D flow has extra advantages, of being
able to visualize flow pattern, vorticity and to predict aortic growth. In
ASD patients it can measure shunt volume directly following the septum
frame by frame. In Fontan patients in can visualize better than standard
MRI the Fontan circuit and it can measure flow at multiple points along
the Fontan circuit. We observed in our Fontan population that shunt lesions
were very common, most of the time via veno-venous collaterals.
Further using advanced computations, we showed that WSS angle was
the only independent predictor of aortic growth in BAV patients. We also
showed the feasibility of GLS analysis on 4D flow MRI and presented an
integrative approach in which flow and functional data are acquired in
one sequence.
From the technical point of view, 4D flow MRI has proved to complement
the traditional components of the standard cardiac MR exams, enabling
in-depth insights into hemodynamics. At this moment it proved its added
value, but in most of the cases it is not able yet to replace the standard
exam. This is still due to long scanning times and relatively long
post-processing times.