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Copyright © 2017 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
CE: D.C.; ON-17-226; Total nos of Pages: 4;
ON-17-226
Pain Free 3 T MRI Scans in Cochlear Implantees
Ingo Todt, yAnja Tittel, Arne Ernst, yPhilipp Mittmann, and ySven Mutze
Department of Otolaryngology, Head and Neck Surgery; and
y
Department of Radiology, Unfallkrankenhaus Berlin, Berlin, Germany
Objective: For cochlear implant recipients, undergoing mag-
netic resonance imaging (MRI) scans is associated with
safety risks and potential side effects. Even following safety
guidelines, potential complications (e.g., pain, magnet dislo-
cation, image artifacts) are possible during 1.5 Tesla (T)
MRI scans. The stronger static magnetic field of a 3.0 T
scanner is associated with further risks of complication,
including implant demagnetization. These complications led
to the recent development of rotatable internal receiver
magnets with a diametrical magnetization.
The aim of this study was to evaluate the potential
occurrence of pain during 3.0 T MRI scans for cochlear
implant recipients with a rotatable, diametrically magnetized
implant magnet.
Patients: Five patients implanted with a cochlear implant
diametrically magnetized magnet.
Intervention: MRI scanning at 3 T.
Main Outcome Measure: In the prospective patient study
an MRI scan was performed on five implantees and the
degree of pain was evaluated by a visual analog scale. Scans
were performed initially with a magnet-supporting headband,
and depending on the degree of discomfort/pain, repeated
without the headband.
Results: In all the patients, all the MRI scans were
performed without any pain, even without the use of the
supportive headband. Demagnetization was clinically not
observed.
Conclusion: 3.0 T MRI scanning can be performed on
cochlear implant recipients with a rotatable diametrically
magnetized internal magnet without risk of the most frequent
cochlear-implant-related MRI complication: pain. This find-
ing enables the expansion of MRI scanning indications up to
3.0 T without complication. Limitations in terms of MRI
artifact still persist. Key Words: Cochlear implant—
MRI—Pain.
Otol Neurotol 38:xxx–xxx, 2017.
Cochlear implantation is the treatment of choice for
patients with severe to profound sensorineural hearing
loss and is an increasingly more common treatment
option for patients with moderate and single-sided deaf-
ness. So far, approximately 400,000 patients have
received a cochlear implant.
Similar to cardiac pacemakers, magnetic resonance
imaging (MRI) observations in cochlear implant recip-
ients present significant potential complications. In par-
ticular, the internal magnet used for fixation between the
implant and audio processor requires special consider-
ation. Previous trials with an alternative, magnet-free
implant system did not lead to significant acceptance (1).
MRI interactions with the internal cochlear implant
magnet can lead to a number of difficulties and adverse
events. The magnet can generate significant image arti-
facts, resulting in the inability to assess specific ipsilat-
eral structures (2). However, depending on the scan
sequence used and the position of the implant, image
visibility can be optimized to allow for an assessment of
the cochlea and the internal auditory canal (3,4). Dislo-
cation of a removable internal magnet can occur when
passing through the MRI static magnet field, causing pain
and acting as a source of infections (5). Use of specific
headbands or bandages designed to provide additional
support to maintain the internal magnet’s position is
common and the number of magnet dislocations is
described to be rare (6). The occurrence of pain and
discomfort during the scan is the most frequent compli-
cation with a rate between 45 and 70% (6,7). Often MRI
scans cannot be performed or completed due to pain-
related complications (7). Demagnetization is an addi-
tional risk specific to 3.0 T MRIs and is dependent on the
orientation of the internal magnet with respect to the MRI
magnetic field (2).
The use of an MRI with a cochlear implant recipient
therefore requires special consideration. The different
cochlear implant companies apply different strategies to
enable safe MRI scans of their implant recipients.
Cochlear (Cochlear Corp., Sydney, Australia) recom-
mends the use of headbands for 1.5 T scanning and
has safety approval for 3.0 T MRI scans for most of
their implants, provided the internal magnet is removed.
Address correspondence and reprint requests to Ingo Todt, Depart-
ment of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus
Berlin, Warenerstr.7, 12683 Berlin, Germany; E-mail: todt@gmx.net
This study was supported by Medel, Innsbruck, Austria.
The authors disclose no conflicts of interest.
DOI: 10.1097/MAO.0000000000001569
1
Otology & Neurotology
xx:xx– xx ß2017, Otology & Neurotology, Inc.
Copyright © 2017 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
CE: D.C.; ON-17-226; Total nos of Pages: 4;
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Consequentially, surgery is required pre- and post-MRI
for magnet removal and reimplantation. Advanced Bion-
ics (Advanced Bionics, Sta¨fa, Switzerland) has safety
approval for 1.5 T scanning with the use of a specific
MRI antenna coil cover and a headband for most of their
implants. Oticon Medical (Oticon Medical, Valaudaris,
France) has approval for 1.5 T scans. In contrast to the
other implants presented, their current main device
(Neuro Zti) is screw fixated. MED-EL (MED-EL, Inns-
bruck, Austria) has approval for 1.5 T scanning with the
use of a headband and without magnet removal for their
range of implants. In addition, MED-EL’s SYN-
CHRONY implant contains a diametrically magnetized
and rotatable internal magnet designed to eliminate the
risk of demagnetization.
Cochlear implants usually have an axially magnetized
magnet in the implant (i.e., the magnet has one mag-
netic pole facing toward the skin flap). This allows the
coil and magnet of the externally worn audio processor
to be held magnetically over the implant. When placed
in an MRI scanner, a rotational force from the static
MRI magnet acts upon the implant. With MRI scanners
higher than 1.5 T, the implant magnet would become
weaker.
The SYNCHRONY implant has a magnet that is
rotatable and is diametrically magnetized (i.e., the axis
of magnetization is perpendicular to the axis of the
magnetic disc). This allows the magnet to turn freely
and self-align in response to an external magnetic field,
like the needle of a compass. In an MRI scanner, the
implant magnet can align parallel to the static magnetic
field of the MRI scanner. Therefore, the magnet cannot
weaken and practically no rotational force is acting upon
the implant.
Clinical experiences with the SYNCHRONY implant
during 3.0 T MRI are absent so far. The aim of this
prospective study was to evaluate the occurrence of pain
in cochlear implant recipients with implant systems
containing a rotatable, diametrically magnetized internal
magnet during MRI scans at 3.0 T.
METHODS
The study was approved by the institutional review board of
the Unfallkrankenhaus Berlin, Germany (IRB-ukb-HNO-2016/
10). This study was supported by a grant (MEDEL, Innsbruck,
Austria). Patients gave their written informed consent for the
use of their clinical records in this prospective study.
In this prospective case study five patients underwent a 3.0 T
MRI observation in a tertiary referral center. Between 2014 and
2017, all the patients were implanted with a MED-EL SYN-
CHRONY implant (MED-EL, Innsbruck, Austria) with a dia-
metrically magnetized internal magnet. The implant was
intraoperatively fixed within a drilled implant bed using
resorbable sutures.
All the examinations were performed in a 3.0 T MR imaging
unit (Achieva, Philips Medical Systems, Best, NL). First, the
patients were brought into the MRI scanner with a headband
fixated over the implant. After the evaluation of pain and
inspection of the implant area, the patients were placed inside
the MRI scanner again, this time without a headband.
Scanning parameters:
TSE T2 2 D: TR: 2,500 milliseconds, TE 120 milliseconds,
slice thickness 1.5 mm, reconstruction resolution of 0.18 0.18
1.5 mm, F0 V 130 130, 20 slices.
RESULTS
In all the patients, with and without a headband,an MRI
scan at 3.0 T could be performed with no magnet disloca-
tion or pain-associated complications. In all the cases, a
headband was not necessary to prevent pain or magnet
dislocation. With and without headband, the mean visual
analogue scale in terms of pain was 0 (i.e., no pain).
Figure 1 shows an exemplary MRI scan with the assess-
ment of the implanted cochlea with ipsilateral cochlear
implant at 3.0 T. None of thepatients reported a noticeable
change in the strength of the implant magnet (Fig. 2).
DISCUSSION
MRI scans are now a routine diagnostic tool in radiol-
ogy used on a daily basis worldwide in most modern
FIG. 1. A, MRI T2W at 3 Tsequence scanning of internal auditory canal with CI in place. Specific positioning of the implant receiver magnet
allows for the assessment of the cochlea. B, Lateral overview of the MRI artifact pattern. CI indicates cochlear implant; MRI, magnetic
resonance imaging.
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hospitals. Therefore, the probability that an MRI is
needed within a life time is very high (8). At 1.5 T,
MRI scans with cochlear implant recipients are associ-
ated with artifacts (9), magnet dislocations (5), and as
most frequently reported: pain (6). The stronger static
magnetic field of the 3.0 T MRI presents similar, often
magnified efficacy and safety risks, with the additional
concern of implant magnet demagnetization (2).
Although manufacturers recommend use of a head-
band during an MRI scan to prevent pain and magnet
dislocation, this approach has been shown to be ineffec-
tive (6,7) and can in itself be a barrier to scanning.
Clinically, the effectiveness of two implant modifications
(i.e., screw fixation, diametrical magnetization) to pre-
vent this complication at 1.5 T has been observed. It is
assumed that the screw fixation of a rigid integrated
internal magnet (Oticon ZTI implant) prevents any mag-
net field-related positional change of the receiver. This
holds the implant in place even if the magnetic field force
is laterally applied and tries to lift the implant magnet.
With the increasing number of 3.0 T scanners in
radiological departments, understanding the behavior
of implants in the vicinity of these machines is of
increasing importance.
Although Cochlear (Sydney, Australia) allows 3.0 T
scans if the internal magnet is temporarily explanted, the
MED-EL SYNCHRONY implant includes a diametri-
cally magnetized rotatable internal magnet which self-
aligns parallel with the external magnetic field of the
MRI scanner. This unique ability of the implant magnet
to align with the main magnetic field of the MRI scanner
was obviously helpful to prevent demagnetization at 3.0
T, but the effect on pain prevention is so far unclear. We
were able to show that the implant magnet configuration
prevents the occurrence of pain at 3.0 T. In the five
patients tested, magnet dislocation was not observed.
Subjectively, all the patients reported no change of the
magnetic attachment force of the antenna coil, indicating
an unchanged magnetic function of the internal magnet.
The prevention of pain and magnet dislocation is of
high importance, since these two factors are the most
frequently reported and relevant complications in
clinical practice.
The ability to perform an MRI scan without pain or the
risk of magnet dislocation provides the possibility of
performing 3.0 T MRI scans routinely with only some
limitations (e.g., artifact relevant limitations, Tesla
strength limitations [>3T]).
CONCLUSION
For cochlear implant recipients with a rotatable, dia-
metrically magnetized internal magnet, MRI scanning at
3.0 T can be performed pain free and without the use of
a headband.
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FIG. 2. A, Implant with regular magnet configuration. Implant with a rotational, diametrically internal magnet. B, Rotational, diametric
internal magnet without applied magnetically force. Change of the internal position of the rotational, diametric magnet related to an applied
external magnetic field (arrows show magnetic field direction).
COMPLICATION IN CI PATIENTS 3
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CE: D.C.; ON-17-226; Total nos of Pages: 4;
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