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Variability in RF‐induced heating of a deep brain stimulation implant across MR systems
Author(s) -
Baker Kenneth B.,
Tkach Jean A.,
Phillips Micheal D.,
Rezai Ali R.
Publication year - 2006
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20769
Subject(s) - specific absorption rate , imaging phantom , electromagnetic coil , implant , torso , head (geology) , nuclear medicine , biomedical engineering , materials science , human head , radiofrequency coil , magnetic resonance imaging , electrical conductor , nuclear magnetic resonance , physics , medicine , absorption (acoustics) , computer science , geology , radiology , anatomy , surgery , telecommunications , quantum mechanics , geomorphology , antenna (radio) , composite material
Purpose To compare the MRI‐related heating per unit of specific absorption rate (SAR) profile of a conductive implant between two 1.5‐Tesla/64 MHz MR systems using a transmit/receive (t/r) head coil configuration. Materials and Methods Deep brain stimulation (DBS) leads were configured within a gel‐filled phantom of the human head and torso. Temperature variation at each of four contacts of the bilaterally‐placed leads was monitored using fluoroptic thermometry. MRI was performed using the t/r head coils of two different‐generation 1.5‐Tesla MR systems from the same manufacturer. Temperature changes were normalized to SAR values for the head (ΔT/SAR‐H), and the slope of this ΔT/SAR‐H by time relationship was compared between the two scanners. Results The ΔT/SAR‐H for the implant ranged from 3.5 to 5.5 times higher on one MR system as compared to the other ( P < 0.01) depending on the measurement site. Conclusion The findings support previous observations that console‐reported SAR does not constitute a reliable index of heating for elongated, conductive implants, such as the DBS hardware system tested. In contrast to our previous findings using a t/r body coil, the data presented here reveal marked differences between two MR systems using t/r head coils (the coil configuration was consistent with the implant manufacturer's imaging guidelines). J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.