Parallel transmit pulse design for patients with deep brain stimulation implants
Magnetic resonance in medicine, 2015•Wiley Online Library
Purpose Specific absorption rate (SAR) amplification around active implantable medical
devices during diagnostic MRI procedures poses a potential risk for patient safety. In this
study, we present a parallel transmit (pTx) strategy that can be used to safely scan patients
with deep brain stimulation (DBS) implants. Methods We performed electromagnetic
simulations at 3T using a uniform phantom and a multitissue realistic head model with a
generic DBS implant. Our strategy is based on using implant‐friendly modes, which are …
devices during diagnostic MRI procedures poses a potential risk for patient safety. In this
study, we present a parallel transmit (pTx) strategy that can be used to safely scan patients
with deep brain stimulation (DBS) implants. Methods We performed electromagnetic
simulations at 3T using a uniform phantom and a multitissue realistic head model with a
generic DBS implant. Our strategy is based on using implant‐friendly modes, which are …
Purpose
Specific absorption rate (SAR) amplification around active implantable medical devices during diagnostic MRI procedures poses a potential risk for patient safety. In this study, we present a parallel transmit (pTx) strategy that can be used to safely scan patients with deep brain stimulation (DBS) implants.
Methods
We performed electromagnetic simulations at 3T using a uniform phantom and a multitissue realistic head model with a generic DBS implant. Our strategy is based on using implant‐friendly modes, which are defined as the modes of an array that reduce the local SAR around the DBS lead tip. These modes are used in a spokes pulse design algorithm in order to produce highly uniform magnitude least‐squares flip angle excitations.
Results
Local SAR (1 g) at the lead tip is reduced below 0.1 W/kg compared with 31.2 W/kg, which is obtained by a simple quadrature birdcage excitation without any sort of SAR mitigation. For the multitissue realistic head model, peak 10 g local SAR and global SAR are obtained as 4.52 W/kg and 0.48 W/kg, respectively. A uniform axial flip angle is also obtained (NRMSE <3%).
Conclusion
Parallel transmit arrays can be used to generate implant‐friendly modes and to reduce SAR around DBS implants while constraining peak local SAR and global SAR and maximizing flip angle homogeneity. Magn Reson Med 73:1896–1903, 2015. © 2014 Wiley Periodicals, Inc.
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