MRI-induced heating on patients with Implantable Cardioverter-Defibrillators and Pacemaker: Role of Lead Structure

Abstract

Magnetic Resonance Imaging (MRI) induced heating on patients with metal implants can pose severe health risks and careful evaluations are needed for pacemaker (PM) or implantable cardioverter-defibrillator (ICD) leads to be labeled as ‘MRI conditionally’. Experimental studies in this field have shown a great variability in results and revealed that several aspects can affect the amount of heating induced at the lead tip. The structural parameters of the lead are one of these.

In this study we performed in-vitro temperature measurements of a human-shaped phantom with a PM / ICD implant, exposed to the RF field of a 1.5T MRI scanner. Aim of these measurements is to investigate the role of the lead structure on the induced heating at the lead tip. The same implant configurations were tested for different PM / ICD manufacturers and lead types. A total of 26 configurations were tested, considering both the right and left pectoral implant. The temperature increases induced by the RF field ranged from <0.1°C to 6.9°C.

In the measurements we performed, bipolar leads showed higher heating than unipolar ones (2.2°C versus 0.7°C mean temperature increase), as well as active fix leads than passive fix leads (3.4°C versus 1.4°C mean temperature increase). However, other parameters, such as the number of wires and their arrangement inside the lead, steel need further investigations and do not allow to define general conditions to immediately extend MRI to patients with metal implants.