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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 - Clin Exp Otorhinolaryngol (2012)

Bottom Line: In both devices, alignment magnets were removed for safety.In the 3.0 T images, the metal-based device on the left side generated the significant amount of artifacts.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.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical Engineering and Computer Science, College of Engineering, Seoul National University, Seoul, Korea.

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.

No MeSH data available.


Related in: MedlinePlus

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).
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Figure 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).

Mentions: We adopted the Nurobiosys Nuvoc-A01 implant as a metal-based cochlear implant sample (11). Electronics for power receiving, data decoding, and current stimulation are encased in medical grade titanium packages. Output from a current stimulator chip is delivered to each site of the cochlear electrode array by platinum feedthroughs. Each feedthrough is insulated by a ceramic plate. The joint area between a ceramic plate and a metal package is hermetically sealed by brazing. A platinum coil for power and data transmission is located outside the metal package. A neodymium magnet encased by titanium packages is located at the center of the coil. Joint areas of the metal packages are fused by laser welding. Metal packages, coil, and a magnet are molded by a medical grade silicone elastomer. The magnet is placed in the silicone elastomer pocket, so it can easily be removed and put in. The electrode array is made of Pt:Ir (90:10) wires. Sixteen flame formed ball contacts are encapsulated by a silicone elastomer. Fig. 1A shows an overall apparatus of the Nuvoc-A01 implant. The bottom panel shows an enlarged view of the sixteen-channel cochlear electrode array.


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 - Clin Exp Otorhinolaryngol (2012)

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).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369977&req=5

Figure 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).
Mentions: We adopted the Nurobiosys Nuvoc-A01 implant as a metal-based cochlear implant sample (11). Electronics for power receiving, data decoding, and current stimulation are encased in medical grade titanium packages. Output from a current stimulator chip is delivered to each site of the cochlear electrode array by platinum feedthroughs. Each feedthrough is insulated by a ceramic plate. The joint area between a ceramic plate and a metal package is hermetically sealed by brazing. A platinum coil for power and data transmission is located outside the metal package. A neodymium magnet encased by titanium packages is located at the center of the coil. Joint areas of the metal packages are fused by laser welding. Metal packages, coil, and a magnet are molded by a medical grade silicone elastomer. The magnet is placed in the silicone elastomer pocket, so it can easily be removed and put in. The electrode array is made of Pt:Ir (90:10) wires. Sixteen flame formed ball contacts are encapsulated by a silicone elastomer. Fig. 1A shows an overall apparatus of the Nuvoc-A01 implant. The bottom panel shows an enlarged view of the sixteen-channel cochlear electrode array.

Bottom Line: In both devices, alignment magnets were removed for safety.In the 3.0 T images, the metal-based device on the left side generated the significant amount of artifacts.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.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical Engineering and Computer Science, College of Engineering, Seoul National University, Seoul, Korea.

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.

No MeSH data available.


Related in: MedlinePlus