CT of soft tissue injury and orbital fractures.

Complex orbital rim and fractures of the internal orbital skeleton (orbital walls) are best analyzed by high-resolution axial CT. Optic canal fractures are optimally visualized with thin 1-mm section high-resolution CT scanning. Spiral CT may be used in the acutely injured patient because of its rapid scan technique. This spiral technique provides smooth data sets for three-dimensional reformations and may demonstrate foreign bodies in more than one plane. Another advantage of spiral CT is the capability of CT angiography. MR imaging usually is not the initial modality for the assessment of orbital trauma, but it is helpful in evaluating vascular injuries such as carotid-cavernous sinus fistulas or post-traumatic pseudoaneurysms. In general, CT with contrast injection is not necessary except when traumatic vascular anomalies, such as carotid cavernous, dural fistulas, or thrombosis of the superior ophthalmic vein, are considered in the differential diagnosis.