Abstract W P45: Differentiation of Contrast Extravasation From Intracranial Hemorrhage on Non-Contrast CT After Endovascular Treatment in Patients With Acute Ischemic Stroke

Abstract

Background: Distinction of intracranial hemorrhage (ICH) from contrast extravasation after endovascular treatment is crucial for guiding subsequent management in patients with ischemic stroke. We evaluated the imaging characteristics that can help differentiate these two entities on post-endovascular treatment non-contrast CT (NCCT). Methods: Clinical and neuroimaging data for all patients with acute ischemic stroke who underwent endovascular treatment at two medical centers over a 6-year period were reviewed. The first post- endovascular treatment NCCT was evaluated for presence of parenchymal hyperdense lesion(s). In patients with parenchymal hyperdensity, the lesion was selected with free hand region-of-interest on the axial slice with the highest visual contrast against parenchymal background (i.e. the lesion appears brighter). ICH was defined as a hyperdensity persisting >48 hours on serial follow up CTs or confirmed by MRI study. Results: A total of 135 patients (mean age ± SD, 66.4 ± 15.6 years) were included. The median delay between angiography and the first follow up NCCT was 1.9 hours (interquartile range, 1.3 - 2.9). Of the 135 patients, 74 (55%) patients had hyperdense lesion(s) on NCCT; of whom, 20 met the definition of ICH, and 54 were contrast extravasation, which resolved on follow up CTs. A receiver operating characteristic analysis showed that the average attenuation can differentiate ICH from contrast extravasation with an area under the curve of 0.78 (p=0.01). An average attenuation of <50 Hounsfield Units (HU) was 100% specific for contrast extravasation versus ICH - which was seen in 24/54 (44%) patients with contrast extravasation. Notably, 8/61 (13%) patients with no hyperdense lesion on first follow up CT developed late-onset ICH. Conclusion: In our series, an average attenuation of <50 HU on the axial slice with highest contrast was 100% specific for differentiating contrast extravasation from ICH among patients with hyperdensity on first post-angiography NCCT.