Factors influencing hyperintense vessel sign on FLAIR sequence in cerebral infarction: current study status

Hyperintense vessel sign (HVS) is defined as focal, serpentine, or tubular hyperintensity relative to gray matter in the subarachnoid space or extending into the parenchyma on fluid-attenuated inversion recovery images (FLAIR). HVS could be used for diagnosis of vascular stenosis or occlusion, prediction of ischemic penumbra, and evaluation of clinical outcome. HVS is time-dependent sign, often occurring in early stage of acute cerebral infarction. The degree or location of the artery stenosis can slowdown cerebral artery flow velocity in various degrees. When flow velocity decreases into a certain range, the HVS becomes prominent. The level of collateral circulation and other clinical related factors can affect collateral flow velocity, and the slow retrograde flow is also another important factor affecting HVS. MRI scanning parameters can affect the presentation of HVS on FLAIR. (authors)