Unenhanced steady state free precession versus traditional MR imaging for congenital heart disease

Non-invasive imaging prior to percutaneous pulmonary valve implantation

The majority of patients with congenital heart disease who have undergone open heart surgery during childhood are possible candidates for additional transcatheter or surgical interventions. One fifth of these conditions usually involve the right ventricular outflow tract (RVOT). Percutaneous pulmonary valve replacement (PPVR) has been widely established as an alternative, less invasive option to surgical pulmonary valve replacement (SPVR). The variability of RVOT anatomy and size, the relative course of the coronary arteries and the anatomy of the pulmonary artery branches are factors that determine the success of the intervention as well as the complication rates. Careful and reliable pre-interventional imaging warrants the selection of suitable candidates and minimizes the risk of complications. 2D and 3D fluoroscopy have been extensively used during pre- and peri-interventional assessment. Established imaging techniques such as Cardiovascular Magnetic Resonance (CMR) and Computed Tomography (CT), as well as newer techniques, such as fusion imaging, have proved to be efficient and reliable tools during pre-procedural planning in patients assessed for PPVR.

Role of cardiovascular magnetic resonance end-systolic 3D-SSFP sequence in repaired tetralogy of Fallot patients eligible for transcatheter pulmonary valve implantation

To evaluate the usefulness of cardiovascular magnetic resonance (CMR) 3D steady state free precession (SSFP) sequence acquired at end-systole (ES) in repaired Tetralogy of Fallot (rToF) patients eligible for percutaneous pulmonary valve implantation (PPVI). Between 2012 and 2018, 78 rToF patients were selected for pulmonary valve replacement (PVR) according to CMR criteria. CMR protocol included 3D-SSFP sequence used to assess the right ventricle outflow tract (RVOT) diameters at three levels (pulmonary valve remnant, mid-portion, bifurcation) in mid-diastole (MD) or ES, RVOT length and coronary artery anatomy. In 20 rToF patients without indications for PVR (controls), 3D SSFP sequence was acquired at both cardiac phases (MD and ES) to evaluate RVOT dimension throughout the cardiac cycle. Invasive balloon sizing was recorded in patients undergoing PPVI. The 3D-SSFP sequence was performed in MD on 39 patients and in ES on other 39, of whom 26 patients met the criteria for PPVI. The latter was unsuccessful in ten patients (38%), mainly due (80% of cases) to significant size discrepancy at PV remnant and bifurcation levels (p = 0.019 and 0.037 respectively) between the measurements by 3D-SSFP in MD and those by the balloon size in systole. Significant RVOT size difference between MD and ES was present at mid-portion and bifurcation levels in the PVR candidate group, and at all three-levels in the control group (all p < 0.001). ES 3D-SSFP sequence is able to quantify RVOT dilation in rToF patients at its maximum expansion, thus improving selection of PPVI candidates.