Age and lead configuration matter: A comparative study of RF-induced heating of epicardial and endocardial electronic devices in adult and pediatric anthropomorphic phantoms in 1.5 T MR

BackgroundChildren with congenital heart defects often have life-sustaining indications for a cardiac implantable electronic device (CIED). In children, these devices are typically sewn to the heart epicardium, but the FDA has never licensed an epicardial system as MR-Conditional due to limited data. Childrens hospitals default to either refusing MRI service to a vast majority of pediatric CIED patients or adopting a scan-all strategy based on results from adult studies. We argue that both approaches are flawed, and the risk-benefit decisions should be made on an individual basis. PurposeTo provide evidence-based knowledge on RF-induced heating of CIEDs in children and adults with epicardial and endocardial leads of different lengths. Study TypePhantom Field Strength/Sequence1.5 T. Assessment120 clinically relevant epicardial and endocardial device configurations were implemented in adult and pediatric anthropomorphic phantoms. Temperature rise was recorded during RF exposure at 1.5 T. Statistical TestsMeans comparisons were implemented using two-sample t-tests, reliability analysis using interclass correlation coefficient based on a single rating, absolute-agreement, 2-way mixed-effects model. ResultsThere was significantly higher RF heating of epicardial leads compared to endocardial leads in the pediatric phantom (3.4 {+/-} 3.0 vs. 0.6 {+/-} 0.4 {degrees}C, p<0.001); however, there was no significant difference in the adult phantom (3.0 {+/-} 3.2 vs. 2.0 {+/-} 1.8, p=0.16). Endocardial leads in the pediatric phantom generated significantly less RF heating than in the adult phantom (0.6 {+/-} 0.4 {degrees}C vs. 2.0 {+/-} 1.8 {degrees}C, p<0.001). Data ConclusionBody size and lead length significantly affected RF heating. For models based on younger children with short epicardial leads (e.g., 25cm), RF heating up to 12 {degrees}C was observed, delivering a cumulative thermal dose previously associated with tissue necrosis. In contrast, RF heating in model based on children with endocardial leads was well below the heating expected from physiologic fever (3 {degrees}C).