Pediatric patients needing cardiac imaging typically receive an echocardiogram. But when more critical diagnostic information is needed to care for patients with congenital heart disease (CHD), pediatric cardiologists and surgeons at Johns Hopkins Children’s Center are increasingly using advanced imaging techniques such as cardiac magnetic resonance imaging (MRI).
Cardiac MRI helps physicians better see complex cardiac anatomy, including in adults and children who had prior congenital heart surgery or who have chest scars that make ultrasound imaging more difficult, explains Shelby Kutty, director of pediatric and congenital cardiology. He and pediatric cardiologist Lasya Gaur, director of congenital cardiac MRI, have taken the lead in this area.
“Cardiac MRI provides specific anatomic and functional information such as heart size and valve function, and quantification of blood flow in the heart, to better understand some of the characteristics of heart tissue,” Kutty says. “That can be helpful for diagnosis following major heart surgery, or as a stratification for understanding what’s going to happen a few years down the line.”
“This is specific information that can only be obtained by cardiac MRI, noninvasively without radiation,” adds Gaur. “This is an attractive diagnostic option for pediatric patients as well as adults with CHD, who undergo multiple procedures over the course of their lifetime, sometimes several times a year.”
The team, considered one of the leaders in the country, employs newer MRI technologies such as parametric imaging — a detailed assessment of heart muscle using T1 and T2 mapping, which are techniques that closely mimic noninvasive studies of heart muscle under a microscope. This technology has been applied to various disease states, such as cardiomyopathies, aortic stenosis, arrhythmogenic right ventricular dysplasia and tetralogy of Fallot, to monitor disease progression and evaluate response to treatment. More recently, the technology has demonstrated promise for cardiac inflammation associated with COVID-19.
Another emerging application is four-dimensional (4D) flow MRI, a method to view blood flow properties in the heart and blood vessels. This is especially useful in some postsurgical states and can help delineate complex blood flow patterns in areas of stenosis or abnormal dilations in blood vessels.
“Visual representation of abnormal forces against vessel walls or quantification of high vessel wall stress has obvious appeal in patients with congenital heart disease to detect early changes for lesions that require close follow-up or to plan additional interventions if needed,” Gaur says.
In another innovation, the cardiology group has taken a program for adults that allows for MRI scans of patients with pacemakers and defibrillators and adapted it for people with CHD. Historically, patients who have legacy devices without an MRI safety classification were told they could not receive MRI due to concerns that the machine’s powerful magnet would trigger life-threatening changes in the device settings or localized heat reactions. With the new approach, and under careful monitoring, the cardiac team re-programs the devices to adopt a standard heart rhythm and disable functions that might cause the devices to malfunction while in the MRI scanner. After the scan, devices are checked and returned to their original settings. Even young patients with rare congenital heart disease and a pacemaker or defibrillator can be considered for a cardiac MRI.
Beyond MRI, the team has access to a full complement of imaging options including echocardiography and computerized tomography (CT). Data obtained from MRI and CT are used to guide surgical or interventional procedures, create 3D models of the heart and minimize the amount of invasive diagnostic procedures. Patients are matched carefully with the technique thought to achieve the best results.