Magnetic Resonance Imaging and Computed Tomographic Scanning of Fresh (Green) Wood Foreign Bodies in Dog Orbits

Abstract

Wooden foreign bodies in the orbit can extend into the intracranial cavity without diagnostic clues from the small eyelid entrance wound, from neurologic examination, and from imaging studies such as ultrasound, plain x-rays, or computed tomography (CT) scans. In cadaver magnetic resonance imaging (MRI) studies, dry wood in the orbit can be seen as a negative or hypointense image in contrast to orbital fat. We studied fresh, green wood in dogs to determine the reliability of CT and MRI scans to image hydrated wood. Wood was placed into each orbit of two dogs. After 24 h the wood was removed from one orbit, but not the other. The dogs were then scanned with CT and MRI. Radiologists were asked to determine if any wood had been left in either or both orbits. The fresh wooden foreign bodies could not be detected despite an intensive effort. MRI does not appear to reliably demonstrate fresh wood in the orbit. MRI can show dry wooden foreign bodies that have not become hydrated, but has not yet been reliable in the clinical situation to rule out the presence of wood in the orbit.