The incidence of patients receiving implanted neurostimulation or neuromodulation systems for treatment of neurological disorders and other conditions continues to increase. Because of the inherent design and intended function of neurostimulation systems, including those used for deep brain stimulation (DBS), spinal cord stimulation (SCS), vagus nerve stimulation (VNS), and other similar devices, the electromagnetic fields used for MR procedures may produce a variety of problems. For example, altered function of a neurostimulation system that results from exposure to the electromagnetic fields of an MR system may cause discomfort, pain, or serious injuries to patients.

MRI-related heating has been reported to create the greatest concern for various devices used for neuromodulation. Variables that impact heating include, but are not limited to, the following:

• The specific type of neuromodulation system
• The electrical characteristics of the specific neuromodulation system
• The field strength and RF wavelength of the MR system
• The type of transmit RF coil (i.e. transmit head vs transmit body RF coil) used for MRI
• The amount of RF energy delivered (i.e., the RF power level, SAR)
• The technique used to calculate or estimate SAR used by the MR system
• The patient’s anatomy undergoing MR imaging
• The landmark position or body part undergoing MRI relative to the transmit RF coil
• Theorientation and configuration of the implantable pulse generator (IPG), extension (e.g., the cable connecting the pulse generator (PG) to the implanted lead), and the lead relative to the source of RF energy (i.e. the transmit RF coil)

Importantly, the exact criteria for the particular neurostimulation system with regard to the pulse generator, leads, electrodes, and operational aspects of the device as well as the MR system conditions must be defined by comprehensive testing and carefully followed to ensure patient safety. On-going investigations continue to define the acceptable criteria to permit MR examinations, including those involving 1.5- and 3-Tesla MR systems, to be performed in patients with neurostimulation systems. Importantly, various device manufacturers now have certain neurostimulation systems that have been specially designed to be MR Conditional which have fewer limitations for MR imaging procedures compared to older devices.

REFERENCES

Aziz TZ. Current and future directions of post-deep brain stimulation implant magnetic resonance imaging scanning. World Neurosurg 2011;76:69-70.

Baker K, Nyenhuis JA, Hridlicka G, Rezai AR, Tkach JA, Sharan A, Shellock FG. Neurostimulator implants: Assessment of magnetic field interactions associated with 1.5- and 3.0-Tesla MR systems. J Magn Reson Imag 2005;21:72-77.

Baker KB, Tkach JA, Nyenhuis JA, Phillips M, Shellock FG, Gonzalez-Martinez J, Rezai AR. Evaluation of specific absorption rate as a dosimeter of MRI-Related implant heating. J Magn Reson Imag 2004;20:315-320.

Baker KB, Tkach J, Hall JD, Nyenhuis JA, Shellock FG, Rezai AR. Reduction of MRI-related heating in deep brain stimulation leads using a lead management system. Neurosurgery 2005;57:392-397.

Baker KB, et al. Variability in RF-induced heating of a deep brain stimulation implant across MR systems. J Magn Reson Imag 2006;24:1236-42.

Baker KB, et al. Deep brain stimulation for obsessive-compulsive disorder: using functional magnetic resonance imaging and electrophysiological techniques: Technical case report. Neurosurgery 2007;61(5 Suppl 2):E367-8.

Bhidayasiri R, Bronstein JM, Sinha S, Krahl SE, Ahn S, Behnke EJ, Cohen MS, Frysinger R, Shellock FG. Bilateral neurostimulation systems used for deep brain stimulation: In vitro study of MRI-related heating at 1.5-Tesla and implications for clinical imaging of the brain. Magnetic Resonance Imaging 2005;23:549-555.

Bosma RL, et al. Spinal cord response to stepwise and block presentation of thermal stimuli: A functional MRI study. J Magn Reson Imaging 2015;41:1318-25.

Bronstein JM, et al. Deep brain stimulation for Parkinson disease: An expert consensus and review of key issues. Arch Neurol 2011;68:165.

Buentjen L, et al. Direct targeting of the thalamic anteroventral nucleus for deep brain stimulation by T1-weighted magnetic resonance imaging at 3T. Stereotact Funct Neurosurg 2014;92:25-30.

Cabot E, et al. Evaluation of the RF heating of a generic deep brain stimulator exposed in 1.5?T magnetic resonance scanners. Bioelectromagnetics 2013;34:104-13.

Carmichael DW, et al. Functional MRI with active, fully implanted, deep brain stimulation systems: Safety and experimental confounds. Neuroimage 2007;37:508.

Chhabra V, Sung E, et al. Safety of magnetic resonance imaging of deep brain stimulator systems: A serial imaging and clinical retrospective study. J Neurosurg 2010;112:497-502.

Cheng CH, et al. 1.5-T versus 3-T MRI for targeting subthalamic nucleus for deep brain stimulation. Br J Neurosurg 2014;28:467-70.

Coffey RJ, et al. Magnetic resonance imaging conditionally safe neurostimulation leads: Investigation of the maximum safe lead tip temperature. Neurosurgery 2014;74:215-24.

De Andres J, Valia JC, et al. Magnetic resonance imaging in patients with spinal neurostimulation systems. Anesthesiology 2007;106:779-86.

De Andres J, et al. MRI-compatible spinal cord stimulator device and related changes in patient safety and imaging artifacts. Pain Med 2014;15:815-9.

de Jonge JC, et al. Safety of a dedicated brain MRI protocol in patients with a vagus nerve stimulator. Epilepsia 2014;55:112-5.

Dormont D, et al. Chronic thalamic stimulation with three-dimensional MR stereotactic guidance. Am J Neuroradiol 1997;18:1093-1097.

Elkelini MS, Hassouna MM. Safety of MRI at 1.5-Tesla in patients with implanted sacral nerve neurostimulator. Eur Urol 2006;50:311-6.

Englot DJ, et al. Abnormal T2-weighted MRI signal surrounding leads in a subset of deep brain stimulation patients. Stereotact Funct Neurosurg 2011;89:311-317.

Eryaman Y, et al. Parallel transmit pulse design for patients with deep brain stimulation implants. Magn Reson Med 2015;73:1896-1903.

Finelli DA, Rezai AR, Ruggieri P, Tkach J, Nyenhuis J, Hridlicka G, Sharan A, Stypulkowski PH, Shellock FG. MR-related heating of deep brain stimulation electrodes: An in vitro study of clinical imaging sequences. Am J Neuroradiol 2002;23:1795-1802.

Fraix V, et al. Effects of magnetic resonance imaging in patients with implanted deep brain stimulation systems. J Neurosurg 2010;113:1242-5.

Georgi A-C, Stippich C, Tronnier VM, Heiland S. Active deep brain stimulation during MRI: A feasibility study. Magn Reson in Medicine 2003;51:380-388.

Gleason CA, et al. The effect of magnetic resonance imagers on implanted neurostimulators. Pacing Clin Electrophysiol 1992;15:81-94.

Gorny KR, et al. 3 Tesla MRI of patients with a vagus nerve stimulator: Initial experience using a T/R head coil under controlled conditions. J Magn Reson Imag 2010;31:475-81.

Gupte AA, et al. MRI-related heating near deep brain stimulation electrodes: More data are needed. Stereotact Funct Neurosurg 2011;89:131-40.

Henderson J, Tkach J, Phillips M, Baker K, Shellock FG, Rezai A. Permanent neurological deficit related to magnetic resonance imaging in a patient with implanted deep brain stimulation electrodes for Parkinson’s disease: Case report. Neurosurgery 2005;57:E1063.

Kerl HU, et al. The subthalamic nucleus at 7.0 Tesla: Evaluation of sequence and orientation for deep-brain stimulation. Acta Neurochir (Wien) 2012;154:2051-62.

Kovacs N, Nagy F, Kover F, et al. Implanted deep brain stimulator and 1.0-Tesla magnetic resonance imaging. J Magn Reson Imag 2006;24:1409-12.

Larson PS, et al. Magnetic resonance imaging of implanted deep brain stimulators: Experience in a large series. Stereotact Funct Neurosurg 2008;86:92-100.

Liem LA, van Dongen VC. Magnetic resonance imaging and spinal cord stimulation systems. Pain 1997;70:95-97.

Maldonado IL, et al. Magnetic resonance-based deep brain stimulation technique: A series of 478 consecutive implanted electrodes with no perioperative intracerebral hemorrhage. Neurosurgery 2009;65(6 Suppl):196-201.

Moens M, et al. Spinal cord stimulation modulates cerebral function: An fMRI study. Neuroradiology 2012;54:1399-407.

Mogilner AY, Rezai AR. Brain stimulation: History, current clinical application, and future prospects. Acta Neurochir Suppl 2003;87:115-120.

Mohsin SA, Sheikh NM, Saeed U. MRI-induced heating of deep brain stimulation leads. Phys Med Biol 2008;53:5745-56.

Nazzaro JM, Lyons KE, Wetzel LH, Pahwa R. Use of brain MRI after deep brain stimulation hardware implantation. Int J Neurosci 2010;120:176-83.

Nazzaro JM, et al. Deep brain stimulation lead-contact heating during 3T MRI: Single- versus dual channel pulse generator configurations. Int J Neurosci 2014;124:166-74.

Nolte IS, et al. Visualization of the internal globus pallidus: Sequence and orientation for deep brain stimulation using a standard installation protocol at 3.0 Tesla. Acta Neurochir (Wien) 2012;154:481-94.

Nowinski WL, et al. Simulation and assessment of cerebrovascular damage in deep brain stimulation using a stereotactic atlas of vasculature and structure derived from multiple 3- and 7-Tesla scans. J Neurosurg 2010;113:1234-41

Ostrem JL, et al. Clinical outcomes of PD patients having bilateral STN DBS using high-field interventional MR-imaging for lead placement. Clin Neurol Neurosurg 2013;115:708-12.

Phillips MD, et al. Parkinson disease: Pattern of functional MR imaging activation during deep brain stimulation of subthalamic nucleus--initial experience. Radiology 2006;239:209-16.

Rezai AR, et al. Thalamic stimulation and functional magnetic resonance imaging: Localization of cortical and subcortical activation with implanted electrodes. J Neurosurg 1999;90:583-590.

Rezai AR, Baker K, Tkach J, Phillips M, Hrdlicka G, Sharan A, Nyenhuis J, Ruggieri P, Henderson J, Shellock FG. Is magnetic resonance imaging safe for patients with neurostimulation systems used for deep brain stimulation (DBS)? Neurosurgery 2005;57:1056-1062.

Rezai AR, Finelli D, Ruggieri P, Tkach J, Nyenhuis JA, Shellock FG. Neurostimulators: Potential for excessive heating of deep brain stimulation electrodes during MR imaging. J Magn Reson Imag 2001;14:488-489.

Rezai AR, Finelli D, Nyenhuis JA, Hrdlick G, Tkach J, Ruggieri P, Stypulkowski PH, Sharan A, Shellock FG. Neurostimulator for deep brain stimulation: Ex vivo evaluation of MRI-related heating at 1.5-Tesla. J Magn Reson Imag 2002;15:241-250.

Rezai AR, Phillips M, Baker K, Sharan AD, Nyenhuis J, Tkach J, Henderson J, Shellock FG. Neurostimulation system used for deep brain stimulation (DBS): MR safety issues and implications of failing to follow guidelines. Investigative Radiology 2004;39:300-303.

Rise MT. Instrumentation for neuromodulation. Archives Of Medical Research 2000;31:237-247.

Ryu SI, et al. Asymptomatic transient MRI signal changes after unilateral deep brain stimulation electrode implantation for movement disorder. Stereotact Funct Neurosurg 2004;82:65-9.

Sankar T, Lozano AM. Magnetic resonance imaging and deep brain stimulation: Questions of safety. World Neurosurg 2011;76:71-3.

Sarkar SN, et al. Low-power inversion recovery MRI preserves brain tissue contrast for patients with Parkinson disease with deep brain stimulators. AJNR Am J Neuroradiol 2014;35:1325-9.

Sarkar SN, et al. Utilizing fast spin echo MRI to reduce image artifacts and improve implant/tissue interface detection in refractory Parkinson’s patients with deep brain stimulators. Parkinsons Dis 2014;2014:508576.

Sarkar SN, et al. Three-dimensional brain MRI for DBS patients within ultra-low radiofrequency power limits. Mov Disord 2014;29:546-9.

Shrivastava D, et al. Heating induced near deep brain stimulation lead electrodes during magnetic resonance imaging with a 3T transceive volume head coil. Phys Med Biol 2012;57:5651-65.

Shellock FG. MRI Safety and Neuromodulation Systems. In: Neuromodulation. Krames ES, Peckham PH, Rezai, AR, Editors. Academic Press/Elsevier, New York, 2009.

Shellock FG. MR imaging and electronically-activated devices. Radiology 219:294-295, 2001.

Shellock FG, Audet-Griffin A. Evaluation of magnetic resonance imaging issues for a wirelessly-powered lead used for epidural, spinal cord stimulation. Neuromodulation 2014;17:334-339.

Shellock FG. Begnaud J, Inman DM. VNS Therapy System: In vitro evaluation of MRI-related heating and function at 1.5- and 3-Tesla. Neuromodulation 2006;9:204-213.

Shellock FG, et al. Implantable microstimulator: Magnetic resonance safety at 1.5-Tesla. Investigative Radiology 2004;39:591-594.

Shrivastava D, et al. Effect of the extracranial deep brain stimulation lead on radiofrequency heating at 9.4 Tesla (400.2 MHz). J Magn Reson Imag 2010;32:600-7.

Smith CD, et al. Chapter 16. Health effects of induced electrical currents: Implications for implants. In: Magnetic Resonance: Health Effects and Safety, FG Shellock, Editor, CRC Press, Boca Raton, FL, 2001; pp. 393-413.

Spiegel J, et al. Transient dystonia following magnetic resonance imaging in a patient with deep brain stimulation electrodes for the treatment of Parkinson disease. J Neurosurgery 2003;99:772-774.

Tagliati M, et al. and the National Parkinson Foundation DBS Working Group. Safety of MRI in patients with implanted deep brain stimulation devices. Neuroimage 2009;47 Suppl 2:T53-7.

Thani NB, et al. Accuracy of postoperative computed tomography and magnetic resonance image fusion for assessing deep brain stimulation electrodes. Neurosurgery 2011;69:207-14.

Tronnier VM, et al. Magnetic resonance imaging with implanted neurostimulation systems: An in vitro and in vivo study. Neurosurgery 1999;44:118-25.

Ullman M, et al. A pilot study of human brain tissue post-magnetic resonance imaging: Information from the National Deep Brain Stimulation Brain Tissue Network (DBS-BTN). Neuroimage 2011;54 Suppl 1:S233-

Utti RJ, Tsuboi Y, et al. Magnetic resonance imaging and deep brain stimulation. Neurosurgery 2002;51:1423-1431.

Weise LM, et al. Postoperative MRI examinations in patients treated by deep brain stimulation using a non-standard protocol. Acta Neurochir (Wien) 2010;152:2021-7.

Zekaj E, et al. Does magnetic resonance imaging induce tissue damage due to DBS lead heating? Acta Neurochir (Wien) 2013;155:1677-8.

Zonenshayn M, Mogilner AY, Rezai AR. Neurostimulation and functional brain stimulation. Neurological Research 2000;22:318-325.

Zrinzo L, et al. Clinical safety of brain magnetic resonance imaging with implanted deep brain stimulation hardware: Large case series and review of the literature. World Neurosurg 2011;76:164-72.