Age Matters: A Comparative Study of RF Heating of Epicardial and Endocardial Electronic Devices in Pediatric and Adult Phantoms during Cardiothoracic MRI

Figure 1. (A) Typical trajectory of an endocardial lead. Leads pass through the subclavian vein creating a stereotypical pathway in nearly all patients. In contrast, epicardial devices can have highly varied lead trajectories (B,C).

Figure 2. (A) 3D models of human-shaped pediatric and adult phantoms created from MRI of a 29-month-old child and representative images of an average-sized adult; the phantoms include grids, pillars, and different heights of pillar extensions to adjust the positioning of the CIEDs. (B) Assembled phantoms with implanted CIED and temperature measuring setup; cardiothoracic imaging landmark was used during MR scans. (C) An example of a patient-derived trajectory of an implanted lead obtained from X-ray image; close view of contact between the temperature probe and epicardial lead tip. The pediatric and adult phantom were 3D printed using Rigid 4000 resin (Formlabs, Somerville, MA, USA) and ABS Plastic, respectively. Pillars, holders, and extensions were made of Tough 1500 resin (Formlabs, Somerville, MA, USA).

Figure 3. Representative patient-derived trajectories for each CIED category (24 trajectories in total) in (A) pediatric and (B) adult phantoms.

Figure 4. Simulated incident E field in (A) homogeneous child and (B) adult body models. Note that the incident field is the electric field of the MRI scanner in the absence of any implant. Trajectories of endocardial and epicardial devices are overlaid on the field maps for comparison. Details of simulation setting are provided in the Supplementary Information Figure S2 and Table S2.

Figure 5. Temperature rise in the gel around the tips of the leads with 120 distinct trajectories implanted in pediatric and adult phantoms.

Figure 6. RMS B1+ values and their corresponding RF heating for device configurations that generated highest heating in each category for (A) child and (B) adult phantom. Black dots: RMS B1+ value that generates the temperature rise below 3 °C.