Magnetic resonance assessment of RV remodeling and function

Cardiac magnetic resonance imaging (CMR) provides unique opportunities for the assessment of right ventricular (RV) geometry, function, and myocardial structure. These allow CMR to play a pivotal role in diagnosis, monitoring, and decision-making in pediatric and congenital cardiology. CMR is the reference standard for quantification of RV volume, ejection fraction and mass. Phase contrast flow velocity mapping by CMR offers an accurate measurement of pulmonary blood flow and of the degree of pulmonary regurgitation in the presence of pulmonary valvar insufficiency, for example after Tetralogy of Fallot repair. More recently, CMR has been employed for the quantification of RV strain, rotation, and torsion. CMR allows for the complete visualization of the RV as compared to echocardiography, but is hampered by inferior temporal resolution, particular for the assessment of diastolic function. Scar imaging with late gadolinium enhancement CMR is established as a risk predictor in certain types of congenital and acquired heart disease, although it can be difficult to detect scarring with certainty in the thin walled RV myocardium. For the same reason, the assessment of diffuse myocardial fibrosis in the RV by CMR T1 mapping is challenging. In this chapter we describe the technical underpinnings of CMR for the RV, outline its utility and limitations in pediatric and congenital heart disease, and provide examples on how CMR contributes to clinical decision making.