Improved Image Quality for Cardiac MRI in Children with Pacemakers and Defibrillators

NORTHWESTERN UNIVERSITY FEINBERG SCHOOL OF MEDICINE

Principal Investigator: Gregory Webster, MD, MPH, Northwestern University Feinberg School of Medicine. Dr. Webster is the section chief of pediatric electrophysiology at Ann & Robert H. Lurie Children’s Hospital of Chicago.

Collaborator: Dr. Daniel Kim, the Knight Family Professor of Cardiac Imaging and Director, Center for Translational Imaging Cardiovascular Imaging. He is also a Professor of Radiology at Northwestern University Feinberg School of Medicine.

Cardiac magnetic resonance imaging (MRI) and cardiac implantable devices (CIEDs), such as pacemakers and implantable cardioverter defibrillators (ICDs), are both critical in congenital heart disease. CIEDs improve quality of life and can be lifesaving; they are not usually optional. Children with congenital heart disease frequently require cardiac magnetic resonance imaging (MRI). Physicians rely on MRI data to make informed decisions about clinical care and to plan surgeries. A major clinical problem is that CIEDs produce artifact in the MRI scanner, degrade the quality of the images and make clinical decisions harder. Patients need both CIEDs and hig-quality MRIs.

CIEDs are required to address dangerous slow heart rates (bradycardia, heart block) and fast heart rates (tachyarrhythmias) in children with congenital heart disease. Surgery to repair congenital heart diseases can lead to a lifelong indication for CIEDs, starting in the first weeks of life. Examples include, but are not limited to, AV septal defects, tetralogy of Fallot and transposition of the great arteries. However, congenital heart patients typically require leads sewn to the heart (epicardial leads) due to structural abnormalities, small size and young age at implantation. Unlike transvenous leads for adults and some children, the FDA has never licensed an MRI- compatible or MRI-contingent epicardial lead. Until recently, magnetic resonance imaging (MRI) was only performed in rare epicardial CIEDs because of risks of lead heating. New data that suggest that safe MRI can be performed, even in the setting of epicardial CIEDs. New pediatric guidelines in 2021 issued a revised Class IIB indication (use with caution) for MRI in epicardial CIEDs, rather than a Class III indication (contraindicated).2

As risks are revised downward, we also need to improve the benefits of MRI. We need to reduce image artifact caused by the pulse generator and improve diagnostic quality of MRIs in CIED patients. The generator is closer to the heart in children than adults. Pulse generator artifacts are intensified by the technical difficulties of imaging small hearts and faster pediatric heart rates. While other efforts are focused on decreasing the risks of MRI, this project will increase the rewards by improving image artifact and diagnostic quality.

Because the pediatric market is smaller than the adult market, investments to solve these issues are unlikely without proof-of-concept studies for congenital heart disease. The unique confluence of small hearts, small bodies, and indications for CIEDs means that translational development of these algorithms needs to be launched at the foundation level. If successful, the sequences in this pilot project can be immediately moved to clinical use in congenital heart disease patients who have FDA-approved MRI-contingent CIEDs.

In this prospective study, our objective is to improve imaging quality for patients with CIEDs by translating existing wideband sequences (developed for adults) into pediatric care.