The Effect of Different Contouring Techniques on Cardiac Magnetic Resonance Assessment of Right Ventricular Volumes in Repaired Tetraology of Fallot: Implications on Preoperative Thresholds for Intervention

Participants with repaired tetralogy of Fallot (RTOF) will be identified using existing patient electronic records who have developed chronic pulmonary regurgitation and are undergoing monitoring for right ventricular dilatation. Cardiac magnetic resonance (CMR) is used to facilitate its optimal timing. Pulmonary valve replacement can prevent irreversible right ventricular (RV) dilatation and dysfunction and cardiac magnetic resonance (CMR) is used to facilitate its optimal timing. There are different post-processing techniques published for measuring RV volumes on cardiac magnetic resonance imaging (detailed vs. smoothed and manual vs. automated). The primary aim of this study is to identify whether the choice of myocardial contouring technique affects the preoperative RV volumetric thresholds for intervention. As a secondary aim, the investigators will determine the reproducibility of different contouring methods.