Modified Alberta Stroke Program Early CT Score (ASPECTS) of Contrast Extravasation on Dual-Energy CT Predicts Haemorrhagic Transformation and Poor Outcome After Endovascular Thrombectomy.

PURPOSE: Haemorrhagic transformation (HT) is an unpredictable complication of acute ischaemic stroke with large vessel occlusion following endovascular thrombectomy (EVT), and imaging parameters that are correlated with haemorrhage are unknown. We developed a modified version of the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) by adding a periventricular region to assess cerebral contrast extravasation (CE) on dual-energy computed tomography (DECT) and assessed its predictive value for HT.

METHODS

In total, 101 patients who underwent DECT immediately after EVT were prospectively enrolled. CE was defined as incident hyperdensity on iodine overlay maps. We quantified the CT attenuation in Hounsfield units (HU) and iodine concentration within the CE regions. The modified ASPECTS divided the middle cerebral artery vascular territory into 11 regions and added one region (paraventricular) to the original score. CE was scored as 1 point for each region, and the cumulative score was determined. Follow-up imaging was performed within 7 days postoperatively to confirm the occurrence of HT. A receiver operating characteristic (ROC) curve was constructed to assess the predictive value of various DECT-measured parameters for HT.

RESULTS

Overall, 75/101 (74.3%) patients exhibited CE following EVT, and 47/101 (46.5%) patients exhibited HT. In the ROC curve analysis, the DECT parameter with the maximal area under the curve (AUC) for HT was the modified ASPECTS (AUC=0.87), indicating that patients with a modified ASPECTS >2 were more likely to develop HT (sensitivity: 83.0%, specificity: 83.3%). The maximum iodine concentration (AUC=0.76) and maximum CT attenuation (AUC=0.68) in the hyperdense region were also predictors of postoperative HT.

CONCLUSION

The modified ASPECTS is a practical and sensitive method for assessing postoperative HT risk in patients following EVT.