Abstract:

Transient perivascular inflammation of the carotid artery （TIPIC） is a rare clinical entity characterized by neck pain， typically described as a dull ache， and is often unilateral with variable intensity. This pain can be localized to the lateral neck area and the carotid artery bifurcation. The mechanism of TIPIC is still unclear， possibly due to non-specific inflammation. Imaging examinations are pivotal for diagnosing TIPIC， mainly including the appearance of the vascular wall and the surrounding area. The former mainly refers to the manifestations that affect the blood vessel wall itself. The latter mainly refers to the local infiltration around blood vessels， manifested as irregular soft tissue replacing the adipose tissue around the blood vessels， and mostly occurs at the posterior or lateral part of the bifurcation of the carotid artery. Sonographically， TIPIC is characterized by an "onion-skin" pattern of abnormal hypoechoic soft tissue surrounding the vessels and hypoechoic plaques on the vascular intima. The vascular wall can be eccentrically thickened， but there is typically no significant luminal narrowing or only a mild reduction without hemodynamic impact. Contrast-enhanced imaging reveals the presence of microbubble perfusion enhancement in low echogenic soft tissue lesions. MRI shows a marked perivascular thickening. MRI with contrast shows the enhancement of the perivascular tissue. CT shows a thin， regular hypodense wall thickening， without significant stenosis. Fluorodeoxyglucose positron emission tomography depicts a significant focal uptake surrounding perivascular changes. TIPIC may resolve spontaneously， typically within two weeks. This article reviews the imaging diagnosis of TIPIC.

Key words: Transient perivascular inflammation of the carotid artery, Carotidynia, Ultrasound, Contrast enhancement ultrasound