The impact of CT scanning and ultrasonography on orbital diagnosis.

New methods of soft tissue imaging have revolutionised the investigation of the orbit. The impact of CT scanning and ultrasonography is considered in relationship to established techniques including angiography. The importance of plain X-ray examination and conventional tomography is stressed for the exclusion of non-orbital causes of exophthalmos. In the orbit CT scanning is the best method of establishing the presence of a mass lesion; ultrasonography is useful principally for the investigation of optic nerve problems. Venography is still required in most patients to diagnose and establish the extent of a venous malformation in the orbit; it also has an important part to play in the diagnosis of inflammatory processes. Carotid angiography is now only required in patients with highly vascular orbital tumours, or with suspected arteriovenous anomalies. Plain X-ray examination, CT scanning and venography are regarded as the dominant investigations with conventional tomography, ultrasound, and arteriography playing a subsidiary role.