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Middle ear prosthesis: Significance in magnetic resonance imaging
Mogneric Rex~nonce Imaging. Vol. 5, pp. 405.406. Printed m the USA. All rights reserved.
1987 Copyright 0
0730-725X/87 $3.00 + .OO 1987 Pergamon Journals Ltd.
l Case Report MIDDLE EAR PROSTHESIS: SIGNIFICANCE IN MAGNETIC RESONANCE JOHN
A. LEON
AND 0.
West Virginia University Medical Center, Department
IMAGING
F. GABRIELE
of Radiology, Morgantown,
West Virginia 26506, USA
The Armstrong model of the Schuknecht gel foam and wire prosthesis was tested in the magnetic field of a 1.5 Tesla magnet. The wire component of the prosthesis was found to he non-magnetic. Patients with this prosthesis can therefore undergo MRI examination safely. Two previous articles from the non radiologic literature concerning the magnetic properties of metallic middle ear prostheses are reviewed.
Keywords: Stapes; Middle ear prosthesis; MRI.
CASE REPORT
A 65year-old woman was referred for an MRI examination of the orbits. The woman gave a history of having a middle ear prosthesis implanted in each ear approximately five years ago. The patient did not know if this middle ear prosthesis contained any magnetic parts. The physician who implanted the middle ear prosthesis was contacted and he informed us that the prosthesis did in fact have a wire component. He was not aware of the magnetic properties of this wire. A prosthesis identical to the one implanted in the patient’s ear was obtained from the patient’s surgeon. The prosthesis is an Armstrong model of the Schuknecht gel foam and wire prosthesis made by the Richard’s Company of Memphis, Tennessee (Fig. 1). The prosthesis has a ,004 inch diameter wire which is 4.5 mm in length. The social number is 2140-475-140287. The wire component of this prosthesis is made of 316L stainless steel. The prosthesis was suspended from a plastic block with 4-O silk and placed into the core of a 1.5 Tesla G.E. Signa magnet. The wire component of the prosthesis was unaffected by the magnetic field. In the future, patients with this kind of prosthesic middle ear device can be scanned safely without fear of disIodging the prosthesis and causing hearing loss. DISCUSSION
Fig. 1. Armstrong model of the Schuknecht gel foam and wire prosthesis made by the Richard’s Manufacturing Com-
We were unable to find previous reports of the magnetic properties of middle ear prostheses in the radiol-
pany of Memphis,
RECEIVED319187; ACCEPTED 4/6/87. Address correspondence and reprint requests to John A. Leon, M.D., West Virginia University Medical Center,
Department 26506. 405
Tennessee.
of Radiology,
Morgantown,
West
Virginia
406
Magnetic Resonance Imaging 0 Volume 5, Number 5, 1987
ogy literature. However, after contacting the Richard’s Medical Company we were informed of previously published articles in the ENT literature on this subject. Applebaum and Valvassori’ tested seven different stapedectomy prostheses and found that none of them were affected by the magnetic field of a 1.5 Tesla magnet. Mattucci et al.* tested eight ear prostheses in a 0.6 Tesla magnet and again found that the prostheses were unaffected by the magnetic field. However, these authors also tested cochlear implants (3M cochlear implants of House design and Vienna design)
and found that they exhibited tremendous torque and deflection. They concluded that MRI was safe in patients with any of the tested middle ear prostheses but contraindicated in patients with cochlear implants. REFERENCES 1. Applebaum, E.L.; Valvassori, G.E. Effects of magnetic resonance imaging fields on stapedectomy prostheses. Arch. Otoluryngol. 111:820-821; 1985. 2. Mattucci, K.R. et al. The effect of nuclear magnetic resonance imaging on metallic middle ear prostheses. Otolaryngol. Head Neck Surg. 94:441; 1986.
1987 Copyright 0
0730-725X/87 $3.00 + .OO 1987 Pergamon Journals Ltd.
l Case Report MIDDLE EAR PROSTHESIS: SIGNIFICANCE IN MAGNETIC RESONANCE JOHN
A. LEON
AND 0.
West Virginia University Medical Center, Department
IMAGING
F. GABRIELE
of Radiology, Morgantown,
West Virginia 26506, USA
The Armstrong model of the Schuknecht gel foam and wire prosthesis was tested in the magnetic field of a 1.5 Tesla magnet. The wire component of the prosthesis was found to he non-magnetic. Patients with this prosthesis can therefore undergo MRI examination safely. Two previous articles from the non radiologic literature concerning the magnetic properties of metallic middle ear prostheses are reviewed.
Keywords: Stapes; Middle ear prosthesis; MRI.
CASE REPORT
A 65year-old woman was referred for an MRI examination of the orbits. The woman gave a history of having a middle ear prosthesis implanted in each ear approximately five years ago. The patient did not know if this middle ear prosthesis contained any magnetic parts. The physician who implanted the middle ear prosthesis was contacted and he informed us that the prosthesis did in fact have a wire component. He was not aware of the magnetic properties of this wire. A prosthesis identical to the one implanted in the patient’s ear was obtained from the patient’s surgeon. The prosthesis is an Armstrong model of the Schuknecht gel foam and wire prosthesis made by the Richard’s Company of Memphis, Tennessee (Fig. 1). The prosthesis has a ,004 inch diameter wire which is 4.5 mm in length. The social number is 2140-475-140287. The wire component of this prosthesis is made of 316L stainless steel. The prosthesis was suspended from a plastic block with 4-O silk and placed into the core of a 1.5 Tesla G.E. Signa magnet. The wire component of the prosthesis was unaffected by the magnetic field. In the future, patients with this kind of prosthesic middle ear device can be scanned safely without fear of disIodging the prosthesis and causing hearing loss. DISCUSSION
Fig. 1. Armstrong model of the Schuknecht gel foam and wire prosthesis made by the Richard’s Manufacturing Com-
We were unable to find previous reports of the magnetic properties of middle ear prostheses in the radiol-
pany of Memphis,
RECEIVED319187; ACCEPTED 4/6/87. Address correspondence and reprint requests to John A. Leon, M.D., West Virginia University Medical Center,
Department 26506. 405
Tennessee.
of Radiology,
Morgantown,
West
Virginia
406
Magnetic Resonance Imaging 0 Volume 5, Number 5, 1987
ogy literature. However, after contacting the Richard’s Medical Company we were informed of previously published articles in the ENT literature on this subject. Applebaum and Valvassori’ tested seven different stapedectomy prostheses and found that none of them were affected by the magnetic field of a 1.5 Tesla magnet. Mattucci et al.* tested eight ear prostheses in a 0.6 Tesla magnet and again found that the prostheses were unaffected by the magnetic field. However, these authors also tested cochlear implants (3M cochlear implants of House design and Vienna design)
and found that they exhibited tremendous torque and deflection. They concluded that MRI was safe in patients with any of the tested middle ear prostheses but contraindicated in patients with cochlear implants. REFERENCES 1. Applebaum, E.L.; Valvassori, G.E. Effects of magnetic resonance imaging fields on stapedectomy prostheses. Arch. Otoluryngol. 111:820-821; 1985. 2. Mattucci, K.R. et al. The effect of nuclear magnetic resonance imaging on metallic middle ear prostheses. Otolaryngol. Head Neck Surg. 94:441; 1986.