Magnetic Resonance Imaging at 1.5 Tesla With a Cochlear Implant Magnet in Place

Sharon, Jeffrey D.; Northcutt, Benjamin G.; Aygün, Nafi; Francis, Howard W.

doi:10.1097/mao.0000000000001176

Cited by 32 publications

(46 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Coronal plane views resulted significantly better visibility than the axial ones. This is in alignment with other clinical studies [ 14 , 15 ]. Looking at the ipsilateral posterior fossa anatomy, internal auditory canal, inner ear and cerebellopontine angle, these were found to be partially obscured by artifact but considered acceptable in the best quality MRI sequences.…”

Section: Discussionsupporting

confidence: 93%

“…Artifacts resulted in signal void areas and distortion signals, both influencing the depiction of the brain's structures. MRI sequences and processing algorithms affected the ability to assess anatomical visibility: in particular, planar and spin echo sequences resulted in higher image quality in agreement with the published literature [9,[14][15][16]. Planar T1w and T2w sequences performed equally, as has been previously reported by Crane et al [17].…”

Section: Discussionsupporting

confidence: 87%

“…Sharon et al analyzed one of the largest studies of recipients who received CIs from three different companies: Advanced Bionics, Cochlear Corporation and Med-El. According to the authors, the mean size of the artifact was 46 mm in length and 36 mm in width across all axial sequences for a 1.5 T field strength [ 14 ]. Kim et al described a mean artifact size of 74.3 mm along the long axis and of 41.6 mm along the short axis in 18 CI recipients (3 Med-El, 5 Advanced Bionics and 10 Cochlear Corporation implants) for 1.5 and 3 T MRI scans [ 19 ].…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

MRI-induced artifact by a cochlear implant with a novel magnet system: an experimental cadaver study

Canzi

Aprile

Simoncelli

et al. 2020

Eur Arch Otorhinolaryngol

View full text Add to dashboard Cite

Purposes To primarily evaluate MRI-induced effects for Ultra 3D cochlear implantation in human cadavers in terms of artifact generation and MR image quality. Methods Three human cadaveric heads were submitted to imaging after unilateral and bilateral cochlear implantation. The 1.5 T MR examination protocol was chosen in accordance with our institutional protocol for the assessment of brain pathology. The maximal signal void size was measured according to each sequence and plane. Two experienced neuro-radiologists and one experienced otoneurosurgeon independently evaluated the MR image quality findings. A 4-point scale was used to describe the diagnostic usefulness of 14 brain structures. Results Shape and size of the artifacts were found to be highly related to MRI sequences and acquisition planes. MRI sequences and processing algorithms affected the ability to assess anatomical visibility. Image quality appeared either high or assessable for diagnostic purposes in 9 out of 14 of the ipsilateral structures, in at least one plane. Anatomical structures contralateral to the cochlear implant were highly visible in all conditions. Artifact intrusion clearly improved after application of metal artifact-reduction techniques. In the case of bilateral cochlear implant, a mutual interaction between the two implant magnets produced an additional artifact. Conclusions We performed the first cadaver study aimed at systematically evaluating the MRI-induced artifacts produced by a cochlear implant with a novel four bar magnet system. Specific brain structures can be assessable for diagnostic purposes under 1.5 T MRI, with the cochlear implant magnet in place.

show abstract

Section: Discussionsupporting

confidence: 93%

Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

MRI-induced artifact by a cochlear implant with a novel magnet system: an experimental cadaver study

Canzi

Aprile

Simoncelli

et al. 2020

Eur Arch Otorhinolaryngol

View full text Add to dashboard Cite

show abstract

“…The internal components of the implantthe active circuitry, electrodes, receiver antenna, and magnet-interact with various components of the MR imaging unit. Safety and image quality concerns exist when performing an MR imaging examination on a patient with unilateral or bilateral cochlear implants (1,2).…”

Section: Introductionmentioning

confidence: 99%

MR Imaging and Cochlear Implants with Retained Internal Magnets: Reducing Artifacts near Highly Inhomogeneous Magnetic Fields

et al. 2018

View full text Add to dashboard Cite

The number of patients receiving cochlear implants and auditory brainstem implants for severe to profound sensorineural hearing loss has rapidly increased. These implants consist of an internal component implanted between the skull and the temporal scalp and an external removable speech processor unit. A small magnet within the internal component is commonly used to hold the external speech processor unit in place. Several cochlear implant models have recently received U.S. Food and Drug Administration and European Economic Area regulatory approval to allow magnetic resonance (MR) imaging examinations to be performed under certain specified conditions. The small internal magnet presents a challenge for imaging of the head and neck near the implant, creating a nonlinear magnetic field inhomogeneity and significant MR imaging artifacts. Fat-saturation failures and susceptibility artifacts severely degrade image quality. Typical artifacts at diffusion-weighted imaging and accelerated imaging are exacerbated. Each examination may require impromptu adjustments to allow visualization of the tissue or contrast of interest. Patients may also be quite uncomfortable during the examination, as a result of either imposed magnetic forces or a tight head wrap that is often applied to minimize internal magnet movement. Translational forces and torque sometimes displace the implanted magnet even when a head wrap is used. Diseases such as neurofibromatosis type 2 that are associated with bilateral vestibular schwannomas and hearing loss often require lifelong tumor surveillance with MR imaging. A collaborative team of radiologists, technologists, and/or medical physicists or MR imaging scientists, armed with strategies to mitigate artifacts near implanted magnets, can customize the examination for better visualization of tissue and consistent comparison examinations over time. RSNA, 2018.

show abstract

“…Additionally, the type of MRI sequences governs the degree of artifact, and certain sequences are more limited than others. Diffusion‐weighted sequences, helpful for acute stroke evaluation, and gradient or heme‐sensitive sequences, used to detect blood products, are particularly degraded by magnet artifact 19 …”

Section: Discussionmentioning

confidence: 99%

Impact of Cochlear Implant With Diametric Magnet on Imaging Access, Safety, and Clinical Care

2020

View full text Add to dashboard Cite

Objectives/Hypothesis Review safety and effectiveness of magnetic resonance imaging (MRI) of patients implanted with a cochlear implant (CI) containing a diametric magnet housed within the undersurface of the device. Study Design Retrospective chart review with additional review of MRI at a tertiary‐care children's hospital. Methods Seven patients with mean age of 8.4 years (range = 1.3–19 years) with a diametric magnet in situ during MRI. The intervention comprised one or more sessions of 1.5 T or 3.0 T MRI without a head wrap. The main outcome measures were the occurrence of magnet‐related complications including discomfort and magnet displacement, use of anesthesia or sedation, and clinical usefulness of MRI studies. Results Seven CI recipients underwent 17 episodes of 1.5 or 3.0 T MRI with an in situ diametric magnet. Thirteen of 17 (76%) MRI sessions were completed in awake patients. No patients had device‐related discomfort. No magnet‐related complications occurred. Thirteen of 14 (93%) brain studies were clinically useful despite artifacts. Conclusions The diametric magnet enabled MRI with magnet in situ without the discomfort or magnet displacement associated with removable axial magnets. The reduction in MRI magnet‐related complications occurred because torque is not directed perpendicular and outward from the plane of the magnet, and the magnet is securely contained within its housing. The design of this device increased access and reduced the need for sedation or anesthesia. Level of Evidence 4 Laryngoscope, 131:E952–E956, 2021

show abstract

Magnetic Resonance Imaging at 1.5 Tesla With a Cochlear Implant Magnet in Place

Abstract: MRI image quality with a cochlear implant magnet in situ depends on several factors, which can be modified to maximize image quality in this unique patient population.

Cited by 32 publications

References 10 publications

MRI-induced artifact by a cochlear implant with a novel magnet system: an experimental cadaver study

MRI-induced artifact by a cochlear implant with a novel magnet system: an experimental cadaver study

MR Imaging and Cochlear Implants with Retained Internal Magnets: Reducing Artifacts near Highly Inhomogeneous Magnetic Fields

Impact of Cochlear Implant With Diametric Magnet on Imaging Access, Safety, and Clinical Care

Contact Info

Product

Resources

About