Ocular hazard of metallic fragments during MR imaging at 0.06 T

Area of Science:

• Ophthalmology
• Medical Imaging
• Biophysics

Background:

• Magnetic resonance (MR) imaging utilizes strong magnetic fields.
• Potential risks of ferromagnetic materials in MR environments are a concern.
• Low-field MR imaging (0.06 T) requires specific safety assessments.

Purpose of the Study:

• To evaluate the ocular hazard of ferromagnetic fragments during low-field MR imaging (0.06 T).
• To determine the threshold magnetic field strength for fragment motion in ocular tissues.

Main Methods:

• In vitro experiments using vitreous humor from cow eyes.
• In vivo animal studies involving rabbit eyes.
• Measurement of motion (rotation, translation) for ferromagnetic fragments (0.25-2.2 mm) at varying magnetic field strengths.

Main Results:

• Ferromagnetic fragments exhibited both rotational and translational motion.
• Fragments too small to be detected by plain radiography showed limited movement.
• Observed motion was insufficient to constitute a significant ocular hazard at 0.06 T.

Conclusions:

• Low-field MR imaging at 0.06 T appears to be safe regarding ferromagnetic ocular fragments.
• The risk of ocular injury from small ferromagnetic fragments is low in this specific MR environment.
• Further research may be warranted for higher field strengths or different fragment types.