Parallel transmit pulse design for patients with deep brain stimulation implants
Author(s)Guerin, Bastien; Akgun, Can; Martin, Adrian; Torrado-Carvajal, Angel; Malpica, Norberto; Hernandez-Tamames, Juan A.; Schiavi, Emanuele; Eryaman, Yigitcan; Lopez Herraiz, Joaquin; Adalsteinsson, Elfar; Wald, Lawrence; ... Show more Show less
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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.
DepartmentInstitute for Medical Engineering and Science; Harvard University--MIT Division of Health Sciences and Technology; Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Research Laboratory of Electronics
Magnetic Resonance in Medicine
Eryaman, Yigitcan; Guerin, Bastien; Akgun, Can et al. “Parallel Transmit Pulse Design for Patients with Deep Brain Stimulation Implants.” Magnetic Resonance in Medicine 73, 5 (June 2014): 1896–1903 © 2014 Wiley Periodicals, Inc
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