MRT bei Patienten mit Hörimplantaten mit Magnetausstattung – ein Update

Nospes, S.; Brockmann, Marc A.; Läßig, Anne Katrin

doi:10.1007/s00117-018-0462-9

Cited by 13 publications

(5 citation statements)

References 30 publications

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“…Each CI manufacturer provides their own guidelines concerning MRI corresponding to their specific implant. Special attention is needed with regard to magnetic field strength applied precautions (e.g., head bandage) and MRI settings (1,2,18). Among the possible options for safe performance of the imaging procedure, a head bandage was used in 69% of cases, while the surgical removal of the implant magnet was never performed.…”

Section: Discussionmentioning

confidence: 99%

Magnetic Resonance Imaging in Patients With Hearing Implants – Follow-up on Prevalence and Complications

Loth

Fischer

Hey

et al. 2021

Otology &Amp; Neurotology

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Objective: To examine the number of magnetic resonance imaging (MRI) examinations performed in patients with hearing implants and to quantify side effects or complications related to this procedure. Study Design: Questionnaire. Setting: Tertiary referral center, academic hospital. Patients: One thousand four hundred sixty-onepatients with an implanted hearing system. Intervention: Patients were asked to complete a questionnaire either during a visit to the clinic (304) or by mail contact (1,157) between February 2018 and March 2019. Main Outcome Measures: Number of examinations by means of MRI per patient and number of side effects or complications.Results: A total of 711 questionnaires were returned. After excluding nonvalid information on the questionnaire, 12.8% of patients were identified who had undergone an MRI after having received their hearing implant. Within this group of 91 patients, the most common precaution undertaken was a head bandage (69%). Side effects were mainly pain (37%), followed by anxiety (15%) and tinnitus (9%). The MRI had to be aborted in 14% and dislocation of the magnet occurred in 7% of examinations. Conclusions: Our data indicate that patients undergoing hearing implant surgery need better information about the limitations and requirements of MRI. The occurrence of side effects is likely as only half of the patients in our study group were completely free of symptoms. Dislocation of the implant magnet was observed in several cases, hence patients and physicians need to be educated about this potential complication.

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Section: Discussionmentioning

confidence: 99%

Magnetic Resonance Imaging in Patients With Hearing Implants – Follow-up on Prevalence and Complications

Loth

Fischer

Hey

et al. 2021

Otology &Amp; Neurotology

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show abstract

Section: Discussionmentioning

confidence: 99%

“…In this regard, ultrasound examination in experienced hands allows for precise visualization and diagnose of the pre-interventional magnet's status and consecutive efficient referral of patients to the appropriate repositioning method. Therefore, ultrasound spares the need for x-ray examination that is recommended in various reports (3,(7)(8)(9). Based on our clinical experiences, a high-frequency ultrasound transducer with low penetration depth is recommended for adequate visualization of the magnet and the lip of its housing.…”

Section: Discussionmentioning

confidence: 99%

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Ultrasound-Controlled Manual Magnet Repositioning in Magnet Dislocation of Cochlear Implants

Rupp

Hornung

Balk

et al. 2020

Otology &Amp; Neurotology

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Objective: To investigate whether ultrasound is a helpful and reliable diagnostic tool to survey the status of the magnet previous and after manual repositioning in patients with partially dislocated cochlear implant (CI) magnets and to assess the success rate of a manual repositioning maneuver. Design: A prospective cohort study. Setting: A tertiary referral medical center. Patients: Patients with a cochlear implant who presented with magnet dislocation after magnetic resonance imaging (MRI) between June 1, 2019 and July 15, 2020. Interventions: Manual repositioning of the partially dislocated CI magnet surveyed by pre-and post-interventional ultrasound. Main Outcome Measures: Rate of successfully diagnosed and manually repositioned magnets; complication rate and recurrence rate after initial manual repositioning maneuver. Results: Nine patients presented with a partial magnet dislocation diagnosed by pre-interventional ultrasound following MRI (n ¼ 9 magnets; three ,; eight right-sided implants; 65.4 AE 21.7 yr). All magnets were repositioned manually. The magnets were successfully repositioned at the first attempt in six out of eight patients. Two patients required a second and one patient a third attempt of manual repositioning. Post-interventional ultrasound confirmed the entirely restored magnet position in all cases. During the mean follow-up period of 7.3 months (AE5.4 mo) no patient experienced any complication or recurrent dislocation of the respective magnet. Conclusion: Manual magnet repositioning is a feasible and reliable method with a high success rate for partially dislocated CI magnets. The pre-interventional diagnosis as well as the post-interventional confirmation of the magnet status can be effectively determined by ultrasound. Thus, manual magnet repositioning and ultrasound investigation can be advocated as first-line therapeutic and diagnostic instruments when dealing with partial magnet dislocation.

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“…Nowadays, there are several CI models on the market that are labeled MR-conditional for 1.5T or even 3T (Azadarmaki et al 2014; Todt et al 2017). The main conditions for MRI are limitation of the main magnetic field of the MRI scanner to 1.5T or 3T, removal of the external part of the CI, limitation of the RF power of the MR exam, and, depending on the model, some measures for the internal CI magnet or restriction of patient movements (Nospes et al 2019). Some manufacturers redesigned the magnet housing such that a temporary surgical removal of the magnet became possible.…”

Section: Introductionmentioning

confidence: 99%

Cochlear Implant Magnet Dislocation: Simulations and Measurements of Force and Torque at 1.5T Magnetic Resonance Imaging

2021

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Objectives: Dislocation of the magnet inside the implanted component of a cochlear implant (CI) can be a serious risk for patients undergoing a magnetic resonance imaging (MRI) exam. CI manufacturers aim to reduce this risk either via the design of the implant magnet or magnet housing, or by advising a compression bandage and cover over the magnet. The aim of this study is to measure forces and torque on the magnet for different CI models and assess the effectiveness of the design and preventative measures on the probability of magnet dislocation. Design: Six CI models from four manufacturers covering all the current CI brands were included. Each model was positioned on a polystyrene head with compression bandage and magnet cover according to the recommendations of the manufacturer and tested for dislocation in a 1.5T whole-body MRI system. In addition, measurements of the displacement force in front of the MRI scanner and torque at the MRI scanner isocenter were obtained. Results: Chance of CI magnet dislocation was observed for two CI models. The design of the magnet or magnet housing of the other models proved sufficient to prevent displacement of the magnet. The main cause for magnet dislocation was found to be the rotational force resulting from the torque experienced inside the magnet bore, which ranges from 2.4 to 16.2 N between the models, with the displacement force being lower, ranging from 1.0 to 1.8 N. Conclusions: In vitro testing shows that two CI models are prone to the risk of magnet dislocation. In these CI models, preparation before MRI with special compression bandage and a stiff cover are of importance. But these do not eliminate the risk of pain and dislocation requiring patient consulting before an MRI exam. Newer models show a better design resulting in a significantly reduced risk of magnet dislocation.

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MRT bei Patienten mit Hörimplantaten mit Magnetausstattung – ein Update

Cited by 13 publications

References 30 publications

Magnetic Resonance Imaging in Patients With Hearing Implants – Follow-up on Prevalence and Complications

Magnetic Resonance Imaging in Patients With Hearing Implants – Follow-up on Prevalence and Complications

Ultrasound-Controlled Manual Magnet Repositioning in Magnet Dislocation of Cochlear Implants

Cochlear Implant Magnet Dislocation: Simulations and Measurements of Force and Torque at 1.5T Magnetic Resonance Imaging

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