DETECTION OF ORBITAL FOREIGN-BODIES BY CT - ARE PLAIN RADIOGRAPHS USEFUL

Purpose: To prove the visualisation of orbital foreign bodies by CT. M aterials and methods: In vitro we examined defined small objects of va rious materials (metal, wood, glass, stone) which are common as orbita l foreign bodies. Density and minimum detectable size were studied. Th e findings of 27 patients with suspected orbital foreign bodies were c ompared with the results of plain radiographs, Comberg radiographs, so nography, and surgery. Results: For iron, the minimum detectable size was 0.02 mm(3). A differentiation of various materials by CT was not a lways possible, especially in small objects. There were wide differenc es in density of wood (-600 HU to +130 HU) according to hardness and w ater content. The CT scans correctly showed number and location of for eign bodies. Other methods were inferior in detection of foreign bodie s. Conclusion: In diagnosis of foreign body injuries of the orbit, CT is the imaging method of choice.