Ex-PRESS glaucoma filter: an MRI compatible metallic orbital foreign body imaged at 1.5 and 3T.
OBJECTIVE
To report on the MRI compatibility of the Ex-PRESS glaucoma filtration device, a tiny metallic implant placed into the anterior chamber of the eye that is much smaller than traditional glaucoma shunts, and to educate the radiology community regarding its appearance.


METHODS
Seven patients with Ex-PRESS glaucoma filtration devices were identified that had undergone MRI at San Francisco General Hospital/University of California San Francisco Medical Center by searching and cross-referencing the radiology reporting system and the electronic medical record. MRI images were reviewed for artefact interfering with interpretation. Ophthalmology examinations were reviewed for evidence of complications.


RESULTS
Eighteen individual MRI examinations were performed during 12 unique MRI events on these 7 patients. 13/18 individual MRI examinations and 7/12 MRI events were performed at 3 T with the others performed at 1.5 T. Mean time from Ex-PRESS implantation to MRI was 17.5 months. Mean time from MRI to first ophthalmology examination was 1.1 months and from MRI to latest ophthalmology examination was 6.6 months. Susceptibility artefact did not interfere with image interpretation and no complications related to MRI were encountered.


CONCLUSIONS
The Ex-PRESS glaucoma filtration device appears to be safe for MRI at 1.5 and 3 T and does not produce significant susceptibility artefact to affect diagnostic interpretation adversely.
Department of Radiology and Biomedical Imaging, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA. Electronic address: Marc.mabray@ucsf.edu.
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Mabray
Department of Radiology and Biomedical Imaging, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA. Electronic address: Alina.uzelac@ucsf.edu.
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Department of Radiology and Biomedical Imaging, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA. Electronic address: Jason.talbott@ucsf.edu.
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Talbott
Department of Ophthalmology, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA. Electronic address: LinS@vision.ucsf.edu.
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Lin
Department of Radiology and Biomedical Imaging, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA; Department of Neurology, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA; Department of Neurosurgery, University of California, San Francisco and San Francisco General Hospital, San Francisco, CA, USA. Electronic address: Alisa.Gean@ucsf.edu.
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D000368:Aged; D000369:Aged, 80 and over; D004869:Equipment Safety; D005260:Female; D005547:Foreign Bodies; D020327:Glaucoma Drainage Implants; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008670:Metals; D008875:Middle Aged; D011446:Prospective Studies
D008670:Metals