Radiological predictors of hemorrhagic transformation after acute ischemic stroke: An evidence-based analysis

Abstract

Hemorrhagic transformation (HT) is one of the most common adverse events related to acute ischemic stroke (AIS) that affects the treatment plan and clinical outcome. Identification of a sensitive radiological marker may influence the controversial thrombolytic decision in the setting of AIS and may at a minimum indicate more intensive monitoring or further prophylactic interventions. In this article we summarize possible radiological biomarkers and the role of different radiological modalities including computed tomography (CT), magnetic resonance imaging, angiography, and ultrasound in predicting HT. Different radiological indices of early ischemic changes, large ischemic lesion volume, severe blood flow restriction, blood-brain barrier disruption, poor collaterals and high blood flow velocities have been reported to be associated with higher risk of HT. The current levels of evidence of the available studies highlight the role of the different CT perfusion parameters in predicting HT. Further large standardized studies are recommended to compare the sensitivity and specificity of the different radiological markers combined and delineate the most reliable predictor.

Value of high-density sign on CT images after mechanical thrombectomy for large vessel occlusion in predicting hemorrhage and unfavorable outcome

“…10,18,19,21,35 A recent study has demonstrated that early subtle CT findings strongly predict hemorrhagic transformation, but it has not included areas of hyperdensity as a predictor. 5 Another recent study proposed a metallic hyperdense sign on CT performed immediately after thrombectomy, defined as a focal area superior to 1.0 cm in diameter with maximum CT density superior to 90 HU identified within the non-petechial intracerebral hyperdense lesion in the basal ganglia, which could predict the occurrence of parenchymal hemorrhage at 24 h. 27 However, a smaller cohort publication has questioned the use of density thresholds that would not allow a reliable differentiation between hemorrhage and contrast staining on immediate post-interventional CT. 11 In our cohort, we use the high-density sign without an HU threshold; however, logistic regression showed that increasing CT density significantly increases the odds of hemorrhage. Nevertheless, applying a density threshold of 90 HU did not reach high specificity and sensitivity (specificity of 77.0% and sensitivity of 42%).…”

“…There are, however, diagnostic difficulties to accurately predict which patient will suffer from devastating consequences. 4–7…”

Early Venous Filling Following Thrombectomy: Association With Hemorrhagic Transformation and Functional Outcome

“…As such, there is scarce evidence about the post-recanalization imaging biomarkers available on digital subtraction angiography (DSA). Prominent brain vascularity in the form of capillary blush, arteriovenous shunting and early venous filling (EVF) have been noted immediately after EVT ( 9 ). EVF, defined as the contrast opacification of any cerebral vein before the late arterial phase on post-reperfusion DSA, has previously been shown to be associated with an increased risk of subsequent infarction ( 10 – 12 ), a higher rate of reperfusion hemorrhage (RPH) and worse clinical outcomes ( 10 , 13 ).…”

“…However, in LVO, EVT decision currently relies on perfusion characteristics only when symptom onset exceeds 6 h. There, a favorable mismatch allows to extend the therapeutic window to as far as 24 h post-symptom onset (8). Similarly, perfusion imaging helps to assess the risk of bleeding following EVT, with an increased risk of hemorrhagic transformation in cases with a large ischemic core volume, severe blood flow restriction, blood-brain barrier disruption and poor collateral status (9). However, within 6 h of symptoms onset in LVO, perfusion imaging is not warranted, preventing its use as prognostic tool for clinical outcome or complications in most of cases.…”

Acute reperfusion therapies for acute ischemic stroke patients with unknown time of symptom onset or in extended time windows: an individualized approach

“… 88 In the Endovascular Treatment for Ischemic Stroke (ETIS) registry, increasing age and ASPECTS, smoking, general anesthesia, angiographic poor collaterals and embolization in a new territory independently predicted parenchymal hemorrhage. 89 There have been several reports of neuroimaging markers predicting symptomatic hemorrhagic transformation after recanalization therapies: 90 leucoaraiosis, 91 , 92 high T max (>14 s), 93 low ADC (<550), 94 permeability measures, 95 low cerebral blood volume (CBV). 96 , 97 A patient treated with EVT 11 h after symptom onset with very low CBV on baseline perfusion imaging that developed sICH 10 h after successful recanalization is presented in Figure 4 .…”