Clin Exp Otorhinolaryngol.  2012 Apr;5(Suppl 1):S19-S23.

Magnetic Resonance Imaging Compatibility of the Polymer-based Cochlear Implant

• Kim JH
• Min KS
• An SK
• Jeong JS
• Jun SB
• Cho MH
• Son YD
• Cho ZH
• Kim SJ

Abstract

OBJECTIVES
In this study, we compared the magnetic resonance (MR) image artifacts caused by a conventional metal-based cochlear implant and a newly developed liquid crystal polymer (LCP)-based device.
METHODS
The metal-based cochlear implant system (Nurobiosys Co.) was attached to side of the head of a subject and the LCP-based device was attached to opposite side. In both devices, alignment magnets were removed for safety. Magnetic resonance imaging (MRI) was performed on a widely used 3.0 T and an ultra-high 7.0 T MRI machine. 3.0 and 7.0 T MR images were acquired using T1- and T2*-weighted gradient echo sequences, respectively.
RESULTS
In the 3.0 T images, the metal-based device on the left side generated the significant amount of artifacts. The MR images in the proximity of the metal package were obscured by the artifacts in both axial and sagittal views. On the other hand, the MR images near the LCP-based device were relatively free from the artifacts and clearly showed the brain structures. 7.0 T MR images showed the more severe distortion in the both sides but the metal-based cochlear implant system caused a much larger obscure area than the LCP-based system.
CONCLUSION
The novel LCP-based cochlear implant provides a good MRI compatibility beyond present-day cochlear implants. Thus, MR images can be obtained from the subjects even with the implanted LCP-based neural prosthetic systems providing useful diagnostic information. Furthermore, it will be also useful for functional MRI studies of the auditory perception mechanism after cochlear implantations as well as for positron emission tomography-MRI hybrid imaging.

Keyword

Cochlear implant; Magnetic resonance imaging; MRI compatibility

MeSH Terms

Artifacts
Auditory Perception
Brain
Chimera
Cochlear Implantation
Cochlear Implants
Electrons
Hand
Head
Liquid Crystals
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Magnetics
Magnets
Polymers
Polymers

Figure

• 

  Fig. 1 Nurobiosys' metal-based cochlear implant system (A) and first prototype version of the liquid crystal polymer (LCP)-based cochlear implant system (B). Bottom figure shows extended view of the each 16 channels electrode array. Inset of the (B) is the 1 cm-diameter LCP-based planar cooper coil for power and data transmission (7).

• 

  Fig. 2 Experimental setup to compare magnetic resonance image artifacts caused by metal- and liquid crystal polymer (LCP)-based cochlear implants.

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  Fig. 3 T1-weighted 3.0 T magnetic resonance images of the head: axial (A) and sagittal (B) plane views when the metal- and liquid crystal polymer-based cochlear implants are attached to the left and right side of the head, respectively.

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  Fig. 4 T2*-weighted ultra-high 7.0 T magnetic resonance images of the head: axial (A) and sagittal (B) plane views when the metal- and liquid crystal polymer-based cochlear implants are attached to the left and right side of the head, respectively.

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