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Cochlear Implants and MRI:Experience with over 100 studies performed with magnets in place

Neil S. Patel, MDFellow – Neurotology

Department of OtorhinolaryngologyMayo Clinic, Rochester, MN

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No financial disclosures

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100 MRIs performedper 1000 people in US

Increased accessand utilization of CI

Treatment paradigmthat facilitates CI over ABI

NF2

2013-2019:Emergence of 3.0Tcompatible devices

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79Patients Total Studies Performed

NF2131

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Headwrap Protocol1. 2” x 2” unaltered thermoplastic square (i.e. Aquaplast)

placed over receiver stimulator2. 1 layer of foam tape (i.e. 3M Microfoam)3. Several layers of gauze wrap (i.e. Kerlix)4. 1 layer of self-adherent tape dressing (i.e. Coban)5. Initially injected 2% lidocaine around receiver stimulator,

now often perform headwrap without local anesthesia

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ResultsN (%) or Median (IQR)

PatientsAgeMalesNF2Age < 18Device type documented

”MRI compatible magnet”

79 (100)62 (45-73)

55 (70)12 (15)3 (4)

75 (96)16 (21)

Total MRI studies“Study-ears”: accounts for bilateral CI or CI/ABI combinations

Cochlear ABICochlear CIMED-EL SynchronyAdvanced Bionics 3D

131154

14 (9)82 (53)42 (27)1 (0.6)

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Results

N (% of studies)

Adverse EventsMagnet tilt requiring manual repositioningMagnet displacement requiring OR repositioningPain

Pain that required discontinuation of examination

18 (14)7 (5)7 (5)4 (3)3 (2)

Total studies 131 (100)

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CI 522

Have implantedseveral CI622 recently,no MRIs yet

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Advanced Bionics Ultra3D

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MED-EL Synchrony

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Discussion• Carlson 2015

• 34 studies• 3 (9%) magnet tilt, 2 (6%) displacement requiring OR

• Present study (includes 2015-2018)• 131 studies• 7 (5%) magnet tilt, 7 (5%) displacement requiring OR

• Now headwrap performed by radiology• Specific SAR (specific absorption rate) limitations defined by

manufacturers under the supervision of an MRI physicist

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Magnet Displacement• S/Sx of magnet tilt/displacement

• Pain during exam / after exam is complete

• Palpable “bump”• Inability to retain processor• Late: skin erythema,

breakdown/exposure• Diagnosis

• Clinical exam: offers opportunity to manually re-seat magnet

• X-ray: cannot replace manual exam

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Conclusions• MRI is safe with TIGHT headwrap around

receiver stimulator

• Tilted magnet can be re-seated with pressure

• Remove and replace magnet for:• MR for radiosurgery planning• Artifact concerns

• Removal and replacement probably weakens silastic for removable magnets

• In spite of “MR conditional at 3.0T” devices, artifact may necessitate 1.5T study

Overall AE rate

Tilt/displacement

3% Pain

10%

14%

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Thank You