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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

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

Mentions: Metal- and LCP-based devices are attached with a paper tape to the left and right side of the subject's head, respectively, to compare image artifacts simultaneously. Fig. 2 shows the experimental setup that compares MR image artifacts using both devices. For both devices, the alignment magnet was removed for safety. Two MRI machines were used: a 3.0 T (Magnum, Medinus Co., Yongin, Korea) and an ultra-high 7.0 T research prototype MRI machine (Magnetom, Siemens Co., Erlangen, Germany). Currently, the 7.0 T MRI machine is not available for clinical use. Generally, signal to noise ratio of the MR images is nearly proportional to magnetic-field strength. Thus, we can observe the delicate structure of the brain using 7.0 T MRI even with multiple brainstem nuclei. We included the 7.0 T MRI machine in this study because it will become clinically available in the near future and will eventually substitute the 3.0 T MRI machine. A T1-weighted gradient echo technique (TR, 400 ms; TE, 9 ms) was used to acquire 3.0 T MR images. 7.0 T MR images were acquired using a T2*-weighted gradient echo technique (TR, 576 ms; TE, 17.8 ms). Axial and sagittal plane views of the head were obtained to compare image artifacts created by the two units.


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)

Experimental setup to compare magnetic resonance image artifacts caused by metal- and liquid crystal polymer (LCP)-based cochlear implants.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Experimental setup to compare magnetic resonance image artifacts caused by metal- and liquid crystal polymer (LCP)-based cochlear implants.
Mentions: Metal- and LCP-based devices are attached with a paper tape to the left and right side of the subject's head, respectively, to compare image artifacts simultaneously. Fig. 2 shows the experimental setup that compares MR image artifacts using both devices. For both devices, the alignment magnet was removed for safety. Two MRI machines were used: a 3.0 T (Magnum, Medinus Co., Yongin, Korea) and an ultra-high 7.0 T research prototype MRI machine (Magnetom, Siemens Co., Erlangen, Germany). Currently, the 7.0 T MRI machine is not available for clinical use. Generally, signal to noise ratio of the MR images is nearly proportional to magnetic-field strength. Thus, we can observe the delicate structure of the brain using 7.0 T MRI even with multiple brainstem nuclei. We included the 7.0 T MRI machine in this study because it will become clinically available in the near future and will eventually substitute the 3.0 T MRI machine. A T1-weighted gradient echo technique (TR, 400 ms; TE, 9 ms) was used to acquire 3.0 T MR images. 7.0 T MR images were acquired using a T2*-weighted gradient echo technique (TR, 576 ms; TE, 17.8 ms). Axial and sagittal plane views of the head were obtained to compare image artifacts created by the two units.

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