Myocardial Fibrosis in Congenital Heart Disease and the Role of MRI

Abstract

Progress in the field of congenital heart surgery over the last century can only be described as revolutionary. Recent improvements in patient outcomes have been achieved through refinements in perioperative care. In the current and future eras, the preservation and restoration of myocardial health, beginning with the monitoring of tissue remodeling, will be central to improving cardiac outcomes. Visualization and quantification of fibrotic myocardial remodeling is one of the greatest assets that cardiac MRI brings to the field of cardiology, and its clinical use within the field of congenital heart disease (CHD) has been an area of particular interest in the last few decades. This review summarizes the physical underpinnings of myocardial tissue characterization in CHD, with an emphasis on T1 parametric mapping and late gadolinium enhancement. It describes methods and suggestions for obtaining images, extracting quantitative and qualitative data, and interpreting the results for children and adults with CHD. The tissue characterization observed in different lesions is used to examine the causes and pathomechanisms of fibrotic remodeling in this population. Similarly, the clinical consequences of elevated imaging biomarkers of fibrosis on patient health and outcomes are explored. Keywords: Pediatrics, MR Imaging, Cardiac, Heart, Congenital, Tissue Characterization, Congenital Heart Disease, Cardiac MRI, Parametric Mapping, Fibrosis, Late Gadolinium Enhancement © RSNA, 2023.

Keywords: Cardiac; Cardiac MRI; Congenital; Congenital Heart Disease; Fibrosis; Heart; Late Gadolinium Enhancement; MR Imaging; Parametric Mapping; Pediatrics; Tissue Characterization.

Figure 1:

Late gadolinium enhancement at cardiac MRI. Mid short-axis delayed enhancement image in a 4-year-old boy with bicuspid aortic valve status after Ross operation and resultant coronary obstruction shows areas of subendocardial and midmyocardial enhancement in the inferoseptal and inferior segments, signifying areas of myocardial scarring (arrows). Note the thin-walled right ventricle obscuring identification of scar.

Figure 2:

T1 mapping in patients with single ventricle physiology. Native T1 maps from a mid short-axis plane in patients with (A) hypoplastic left heart syndrome and (B) a hypoplastic right heart. * indicates the hypoplastic chamber with evidence of hypertrophy and dilatation of the dominant ventricles. Free wall regions of interest (violet) are drawn on the free wall of the dominant ventricles, and blood pool regions of interest (blue) are drawn within the blood pool of the dominant ventricle.

Figure 3:

Late gadolinium enhancement (LGE) patterns at MRI in patients with tetralogy of Fallot (TOF). (A) Short-axis delayed enhancement image shows LGE in the area of the transannular patch (arrow). (B) Left ventricular outflow tract delayed enhancement image shows LGE at the ventricular septal defect patch (arrow) in an 18-year-old woman with history of TOF with pulmonary atresia after repair.

Figure 4:

Late gadolinium enhancement (LGE) at MRI in a patient with a systemic right ventricle. Short-axis image shows superior insertion point LGE with midmyocardial anteroseptal extension (arrows) in a 27-year-old male patient with congenitally corrected transposition of the great arteries after mechanical tricuspid valve replacement.

Figure 5:

Late gadolinium enhancement (LGE) patterns at MRI in patients with single ventricle physiology. (A) Short-axis image shows inferior insertion point LGE (arrow) in a 15-year-old adolescent boy with unbalanced atrioventricular canal after Fontan operation. (B) Short-axis image shows LGE (arrow) at the region of ventriculotomy for right ventricle–to–pulmonary artery conduit (Sano shunt) insertion along the right ventricular anterior wall in a 13-year-old adolescent girl with hypoplastic left heart syndrome after Fontan operation.