2021/11/30 by Jasmine Vu, Bhumi Bhusal, Vu, Jasmine +14
Medicine · Neuroscience · #Neurological disorders and treatments #Advanced MRI Techniques and Applications #Functional Brain Connectivity Studies
paper · pdf · doi:10.48550/arxiv.2112.00235
Objectives Studies that assess magnetic resonance imaging (MRI) induced\nradiofrequency (RF) heating of the tissue in the presence of an active\nelectronic implant are mostly performed in horizontal, closed-bore scanners.\nVertical, open-bore MRI systems have a 90\deg rotated magnet and generate a\nfundamentally different RF field distribution in the body, yet little is known\nabout the RF heating of deep brain stimulation (DBS) systems in this class of\nscanners. Here, we investigated whether RF heating of DBS devices was\nsignificantly different in a vertical, open-bore MRI scanner compared to a\nhorizontal, closed-bore MRI scanner. Materials and Methods In this phantom\nstudy, RF heating around the lead of a commercial DBS system implanted in an\nanthropomorphic phantom was evaluated in a 1.2 T vertical open-bore scanner\n(Oasis, Fujifilm Healthcare) and a 1.5 T horizontal closed-bore scanner (Aera,\nSiemens Healthineers). DBS devices were implanted following 30 realistic lead\ntrajectories. Electromagnetic simulations were performed to assess the specific\nabsorption rate (SAR) of RF energy around leads with different internal\nstructures. Results When controlling for B1+rms, temperature increase around\nthe lead-tip was significantly lower at the vertical scanner compared to the\nhorizontal scanner (p-value=9.1x10-7). Electromagnetic simulations demonstrated\nup to a 14-fold reduction in the maximum 0.1g-averaged SAR deposited in the\ntissue surrounding the lead-tip in a vertical scanner compared to a horizontal\nscanner for leads with straight and helical internal wires. Conclusions RF\nexperiments and electromagnetic simulations demonstrated consistently lower RF\nheating and power deposition around the DBS lead-tip at the vertical scanner\ncompared to the horizontal scanner. Our simulation results suggest that this\ntrend in heating may potentially extend to leads from other manufacturers.\n