Glatt H J, Custer P L, Barrett L, Sartor K
Department of Ophthalmology, Washington University School of Medicine, St. Louis, Missouri.
Ophthalmic Plast Reconstr Surg. 1990;6(2):108-14. doi: 10.1097/00002341-199006000-00005.
Wooden foreign bodies in the orbit are not detectable by standard roentgenography. Reports in the literature on the ability of computed tomography (CT) to detect orbital wooden foreign bodies have varied. To evaluate whether magnetic resonance imaging (MRI) would offer any advantage over CT in detecting wood in the orbit. MRI and CT were performed on an in vitro model of wooden foreign bodies in the orbit. Woods of different types and sizes were studied in vegetable fat backgrounds chosen to simulate orbital fat. On CT, most types of wood were hypodense to fat. Appropriate window settings were critical in the detection of wood by CT: in this model, a window width of 1000 Hounsfield units was optimal. On MRI, all types of wood were hypointense to fat. Small pieces of wood were surrounded by an MRI truncation artifact consisting of hyperintense spots. T1-weighted images demonstrated wood better than T2-weighted images and required less scanning time than either proton density or T2-weighted images, MRI was superior to CT in detecting the smallest pieces of wood. The role of MRI in the detection of orbital wooden foreign bodies in clinical practice remains to be determined.
眼眶内的木质异物无法通过标准的X线摄影检测到。文献中关于计算机断层扫描（CT）检测眼眶木质异物能力的报道各不相同。为了评估磁共振成像（MRI）在检测眼眶内木质异物方面是否比CT具有任何优势，对眼眶内木质异物的体外模型进行了MRI和CT检查。在选择模拟眼眶脂肪的植物脂肪背景下，研究了不同类型和大小的木材。在CT上，大多数类型的木材相对于脂肪呈低密度。合适的窗宽设置对于CT检测木材至关重要：在该模型中，1000亨氏单位的窗宽是最佳的。在MRI上，所有类型的木材相对于脂肪呈低信号。小块木材被由高信号斑点组成的MRI截断伪影所包围。T1加权图像比T2加权图像能更好地显示木材，并且比质子密度加权或T2加权图像所需的扫描时间更少，MRI在检测最小的木材碎片方面优于CT。MRI在临床实践中检测眼眶木质异物的作用仍有待确定。
