The "dense artery sign"--major cerebral artery thromboembolism demonstrated by computed tomography.

A 4 years review of high resolution thin slice (3-5 mm) computed tomography performed within 24 h after cerebral infarction revealed increased density in a major cerebral artery segment in 28 patients. Arteries affected were the vertebral and basilar artery in 6 and 8 patients, the sphenoid course of the middle cerebral artery in 13 cases and the extracranial internal carotid artery in 1 patient. In 35.7% of cases the so called "dense artery sign" provided earliest evidence of the ensuing infarction documented by CT controls in most patients. Angiography carried out in 8 patients, density calculations in the course of the affected vessel and resolution of the increased density on subsequent CT examinations suggest thrombembolism as the most likely etiology. In the clinical setting of acute stroke increased artery density encompassing the entire vessel diameter may serve as an early indicator of major cerebral artery occlusion and prompt angiographic investigation of a lesion potentially amenable to lysis.