Neuroimaging predictors of hemorrhagic transformation of ischemic stroke

Hemorrhagic transformation (HT) is a serious complication that worsens outcomes and increases mortality in patients with ischemic stroke (IS). HT can occur both spontaneously and after reperfusion therapy. Severe ischemic injury in IS is not sufficient in itself to cause HT; one of the key elements in its development is reperfusion. Delayed reperfusion in the area of severe ischemic injury mainly increases the likelihood of HT due to disruptions in the blood-brain barrier (BBB), which, in turn, play a key role in the formation of HT in the acute period of IS. Currently, perfusion CT and MRI are the most widely used imaging methods for assessing the patient's condition and predicting clinical outcome. To assess the degree of ischemic injury, there are various neuroimaging indicators that reflect the level of ischemic damage in IS and can be used as predictors of HT. To date, the most reliable tools for assessing the risk of HT include very low cerebral blood volume (VLCBV), time to reach maximum concentration of contrast agent (Tmax), permeability surface-area product (PS), lesion volume in diffusion-weighted images (DWI), and poor collateral circulation.