Magnetic susceptibility artifact in orbital magnetic resonance imaging.

Case report of a 16-year-old boy presenting with total hyphema due to blunt trauma to the left eye. During a subsequent cinematic MRI scan to identify salvageable lateral rectus muscle, the attachment of the left lateral rectus was obscured by a 20-mm diameter signal void. A subsequent CT scan for a suspected metallic foreign body revealed the muscle attachment after all. The theoretical explanations for this finding are discussed.