Frandics Pak Chan MD, PhD, Presenter: Nothing to Disclose

Tetralogy of Fallot (TOF) is the most common cyanotic heart disease, representing 10% of all cases of congenital heart disease. The most frequent and important clinical indication for cardiac MRI in patient with TOF is the evaluation of impending right heart failure after total surgical repair. In young patients, total repair of TOF calls for closure of the ventricular septal defect and relief of the subvalvular, valvular, supravalvular pulmonary stenosis, the latter often accomplished with transannular patch augmentation. This leaves a varying degree of pulmonary regurgitation. While most patients tolerate the additional volume load to the right ventricle, about 10% of these patients progress to right-heart failure, necessitating surgical or transvascular pulmonary valve replacement. Since all artificial valves have limited longevity and once placed they will likely require future replacement, this operation is ideally done just before irreversible RV failure. In current clinical practice, this event is estimated by ventricular sizes and ejection fractions. Cardiac MRI provides the most accurate measurements of these markers. The precise thresholds for these markers are being investigated by ongoing clinical studies. Despite the demonstrated utility of cardiac MRI and the clinical needs to follow an increasing number of patients with repaired TOF, the availability of high-quality MRI study remains limited outside academic centers. The reasons may be traced to the high cost, the length, and complexity of the examination. These limitations are workflow related and may be ameliorated by volumetric acquisition of anatomic and flow information with 4D phase-contrast (4DPC) imaging technique. In the past few years, the performance of 4DPC in terms of acquisition time, temporal resolution, and image quality have improved significantly. Versions of 4DPC are being implemented by scanner manufacturers. User friendly, efficient software programs are becoming available for visualization and quantitative analysis of the 4DPC image data. Deployment of these technologies facilitates cardiac MRI study of patients with congenital heart disease, including TOF.

Chan, F, Cardiac Keynote Speaker: Imaging Repaired Tetralogy of Fallot—Current Practice and Future Developments.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14044526.html