Computed tomography of the orbit

In less than a decade computed tomography (CT scanning) had a profound impact on diagnostic radiology. Radiology of the orbit is no exception. As early as 1973, reports published in the radiological literature indicated that this new noninvasive imaging method was a highly effective way of demonstrating intraorbital mass lesions. As CT scanners became widely available, computed tomography became a significant adjunct to ophthalmological diagnosis. Today the main indications for CT scanning of the orbit are (1) suspected mass lesions, most frequently presenting as exophthalmos, (2) orbital trauma, including foreign bodies, (3) some congenital anomalies, and (4) suspicion of extension into the orbit of extraorbital disease processes. Along with ultrasonography, another new noninvasive imaging technique, CT has replaced a number of more invasive and often less effective diagnostic methods, such as orbital pneumography, venography, and arteriography as major imaging techniques in orbital pathology. The paper discusses current practices in the technique of CT scanning of the orbit including the important aspect of radiation dosimetry and the clinical applications, using a number of cases to illustrate its use.