Purpose: In the 2017 Heart Rhythm Society consensus statements, scanning of MR nonconditional CIEDs in the presence of epicardial leads were classified as contraindications. While there are numerous studies on transvenous leads, there is insufficient data to comment on the safety of patients with epicardial leads during MRI. This study seeks to clarify safety concerns in patients with epicardial leads owing to the sensitivity of its applications.
Methods: a tissue-equivalent phantom was designed according to the ASTM standard for measurement of radiofrequency (RF) induced heating on or near passive implants. The polycarbonate phantom and was filled with a polyacrylic acid (PAA) gel-saline that has similar electrical and thermal properties with the human body tissue. Forms fabricated to hold the lead and fluoroptic temperature probes permits easy localization and configuration (lead length and shape) within the gel. An initial thermometric study was performed on a 3T Siemens Tim Trio MRI system with routine clinical pulse sequences on a straight 58.4cm bipolar epicardial lead positioned in the phantom at a depth of 5cm below the surface.
Results: Preliminary data shows no significant heating above the background in presence of the lead for all pulse sequences examined.
Conclusion: The design of the phantom, lead, and temperature probe holder permits a rapid determination of the potential heating that may occur during an MRI study given the specific presentation of the lead within the patient. The system is relatively easy to setup and use within the clinic and can provide additional information to better evaluate safety concerns with border-line cases where the potential benefit of MRI may outweigh the risks. Further investigation on the variation of induced RF heating with lead type, insulation, lengths, and presentation within the body are underway and will be discussed.