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Magnetic resonance imaging in preseptal ferromagnetic foreign bodies
Tu-An Ma1, Khizar Rana1, Jessica Y Tong1
1Department of Ophthalmology and Visual Sciences, University of Adelaide, Adelaide, South Australia.
Objective:
To review the literature on safety of magnetic resonance imaging (MRI) in patients with preseptal ferromagnetic foreign bodies.
Methods:
We describe 3 cases of MRI in patients with preseptal ferromagnetic foreign bodies (FFBs) from our institution.
Results:
The FFBs were all preseptal, adjacent to the medial canthus (n = 2) and lateral canthus (n = 1). None of the patients had any ocular complications post-MRI. The literature review identified an additional 7 cases with intraocular and preseptal FFBs that underwent MRI. The FFBs ranged in size from 1.0 mm to 3.5 mm. The FFBs were intraocular (n = 6), or preseptal (n = 1). The MRI field strength ranged from 0.35 T to 1.5 T. Five (83.3%) of the patients with intraocular FFBs had ocular complications, which included hyphema (n = 2), cataract (n = 3), vitreous haemorrhage (n = 1), and corneal scar (n = 1). The patient with preseptal FFB did not have post-MRI complications.
Conclusions:
There is some evidence to suggest that patients with preseptal FFBs may be less likely to experience complications post-MRI compared to intraocular FFBs. Various factors affect the safety of MRIs, including FFB location, size, proximity to visually-significant structures, and MRI field strength.
Insights
Magnetic resonance imaging (MRI) appears safe for patients with preseptal ferromagnetic foreign bodies (FFBs). Studies suggest preseptal FFBs carry a lower risk of ocular complications compared to intraocular FFBs during MRI scans.
Area of Science:
- Ophthalmology
- Radiology
- Medical Imaging
Background:
- Ferromagnetic foreign bodies (FFBs) in the eye pose a risk during magnetic resonance imaging (MRI).
- Preseptal FFBs are located outside the eyeball, while intraocular FFBs are within the eye.
Purpose of the Study:
- To evaluate the safety of MRI in patients with preseptal ferromagnetic foreign bodies.
- To compare complication rates between preseptal and intraocular FFBs undergoing MRI.
Main Methods:
- Review of literature on MRI safety in patients with preseptal FFBs.
- Case series of 3 patients with preseptal FFBs undergoing MRI.
- Analysis of reported ocular complications in relation to FFB location, size, and MRI field strength.
Main Results:
- No ocular complications were observed in the 3 patients with preseptal FFBs.
- Literature review identified 7 additional cases (6 intraocular, 1 preseptal FFBs).
- Intraocular FFBs were associated with significant ocular complications (83.3%), including hyphema, cataract, and vitreous hemorrhage, unlike preseptal FFBs.
Conclusions:
- Preseptal ferromagnetic foreign bodies may be associated with a lower risk of ocular complications during MRI compared to intraocular FFBs.
- Factors influencing MRI safety include FFB location, size, proximity to ocular structures, and MRI field strength.
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