Local specific absorption rate in XXXX at 7 tesla.

@entity1 @entity5 @entity1313
PURPOSE: MR safety at 7 Tesla relies on accurate numerical simulations of transmit electromagnetic fields to fully assess local specific absorption rate (SAR) safety. Numerical simulations for SAR safety are currently performed using models of healthy @entity1 . These simulations might not be useful for estimating SAR in @entity1 who have large lesions with potentially abnormal dielectric properties, e.g., @entity1313 . THEORY AND METHODS: In this study, @entity1313 @entity1 models are constructed based on scans of four @entity1 with high grade @entity1313 . Dielectric properties for the modeled @entity5 are assigned based on electrical properties tomography data for the same @entity1 . Simulations were performed to determine SAR. RESULTS: Local SAR increases in the @entity5 by as much as 30%. However, the location of the maximum 10-gram averaged SAR typically occurs outside of the @entity5 , and thus does not increase. In the worst case, if the @entity5 model is moved to the location of maximum electric field intensity, then we do observe an increase in the estimated peak 10-gram SAR directly related to the @entity5 . CONCLUSION: Peak local SAR estimation made on the results of a healthy @entity1 model simulation may underestimate the true peak local SAR in a @entity1313 @entity1 . Magn Reson Med, 2015.    2015 Wiley Periodicals, Inc.
