Advances in surgery, catheter-based interventional therapies, intensive care, and medical management have dramatically changed the landscape of congenital heart disease (CHD), and the complexity of the anatomy and physiology of patients surviving with CHD has increased. The majority of patients will survive to adulthood, although the need for reintervention is common. Imaging has been one vehicle that has fueled these advances; in addition, the developments in the other fields mentioned earlier have placed new demands on imaging to diagnose and guide management. There are a number of imaging modalities available to the clinician when it comes to these evaluations.
Echocardiography remains a mainstay of imaging. Despite its importance in rapid diagnosis and follow-up, it has limitations. The presence of postoperative scar, chest wall deformities, overlying lung tissue, and body habitus sometimes results in suboptimal transthoracic windows. In addition, limited fields of view, artifacts from valves or other foreign structures, and its inherent 2-dimensional nature confine its usefulness. Transesophageal echocardiography provides improved acoustic windows but has a narrow field of view, offers limited assessment of extracardiac structures such as the branch pulmonary arteries, and is more invasive.
Cardiac catheterization employing x-ray fluoroscopy and contrast angiography has an expanding role in minimally invasive interventions, but its role as a diagnostic procedure is rapidly diminishing. In addition to the poor soft tissue contrast, its inherent 2-dimensional nature, hindrance from overlapping structures, and the substantial ionizing radiation (particularly in pediatric patients) makes fluoroscopy ill-suited for diagnostic and functional analysis. With many CHD survivors, repeat surveillance imaging is often required, and the cumulative radiation dose is a concern.
This chapter focuses on the evolving and expanding roles of other imaging modalities in diagnosing and monitoring patients with CHD, including cardiac magnetic resonance imaging (CMR), cardiac computed tomography (CT), and radionuclide scintigraphy.
CARDIAC MAGNETIC RESONANCE IMAGING
CMR has emerged as an alternative, complementary, and frequently superior imaging modality for investigating anatomy, function, and tissue characterization in the patient with CHD. It has many advantages over other modalities, and because of its wide variety of applications, it has been termed a “one-stop-shop” of imaging. Unlike CT and radionuclide studies, CMR does not involve radiation, making it quite suitable for repeat examinations. Additionally, the contrast is gadolinium or iron based and much less allergenic than iodine-based contrast typically used in CT. This is particularly important in a population of patients who have been and continue to be exposed to large doses of radiation and contrast agents during hemodynamic and interventional catheterization. It is not limited by echocardiographic windows and has a wide field of view. CMR is the reference standard for ventricular volumetric, functional quantification and blood flow, which is quite often a key component for CHD survivors. Major advances in magnetic resonance imaging (MRI) hardware and software including advanced coil design, faster gradients, new pulse sequences, and faster image reconstruction techniques, ...