Straight artery sign in extracranial carotid artery dissection.

ABSTRACT

BACKGROUND AND PURPOSE: Magnetic resonance imaging (MRI) has become generally accepted as a non-invasive method to provide the definitive diagnosis of cervicocerebral vessel dissection. The finding of an intramural hematoma on axial MR images is the characteristic sign of the disease. However, there has been no previous report of the characteristic magnetic resonance angiographic (MRA) findings. METHOD: The authors retrospectively reviewed MRI and MRA findings of patients with spontaneous extracranial carotid dissection. The most striking finding on MRA was the straightness of the affected artery when compared to the non-affected side of the same patient. For quantitative measurement, "Carotid Straightness Index (CSI)" was developed to measure the straightness of the arteries and compared the indices of both extracranial internal carotid arteries in the same patient. RESULTS: The patients' age range was from 21-55 years (mean 38 years). There were 6 males and 3 females. All patients had the classical "Straight artery sign" on the MRA. The carotid straightness index was significantly higher in the affected artery when compared to the normal side of the same patient. CONCLUSION: The straight artery sign and the carotid straightness index can be very useful for early detection of the extracranial carotid dissection. It can be found in early stage disease or in less severe forms of carotid dissection where significant narrowing is not demonstrated.