CONCENTRATION OF THE SPECIFIC ABSORPTION RATE AROUND DEEP BRAIN STIMULATION ELECTRODES DURING MRI

During Magnetic Resonance Imaging (MRI), the presence of an implant such as a Deep Brain Stimulation (DBS) lead in a patient's body can pose a signiflcant risk. This is due to the fact that the MR radiofrequency (RF) fleld can achieve a very high strength around the DBS electrodes. Thus the speciflc absorption rate (SAR), which is proportional to the square of the magnitude of the RF electric fleld, can have a very high concentration in the near-fleld region of the electrodes. The resulting tissue heating can reach dangerous levels. The degree of heating depends on the level of SAR concentration. The efiects can be severe, leading to tissue ablation and brain damage, and signiflcant safety concerns arise whenever a patient with an implanted DBS lead is exposed to MR scanning. In this paper, SAR, electric fleld, and temperature rise distributions have been found around actual DBS electrodes. The magnitude and spatial distribution of the induced temperature rises are found to be a function of the length and structure of the lead device, tissue properties and the MR stimulation parameters.