CT of soft tissue injury and orbital fractures

Complex orbital rim and fractures of the internal orbit al skeleton (orbita l walls) are best analyzed by high-resolution axial CT. Optic canal fractur es are optimally visualized with thin 1-mm section high-resolution CT scann ing. Spiral CT may be used in the acutely injured patient because of its ra pid scan technique. This spiral technique provides smooth data sets for thr ee-dimensional reformations and may demonstrate foreign bodies in more than one plane. Another advantage of spiral CT is the capability of CT angiogra phy. MR imaging usually is not the initial modality for the assessment of o rbital trauma, but it is helpful in evaluating vascular injuries such as ca rotid-cavernous sinus fistulas or post-traumatic pseudoaneurysms. In genera l, CT with contrast injection is not necessary except when traumatic vascul ar anomalies, such as carotid cavernous, dural fistulas, or thrombosis of t he superior ophthalmic vein, are considered in the differential diagnosis.