Usefulness of Non-Contrast Electron Density Imaging for the Identification of Brain Tissue Changes in Large Vessel Occlusion Acute Ischemic Stroke

Background: Electron density (ED) imaging has shown the ability to discriminate between different soft tissue components in preliminary studies. We hypothesized that ED might improve the identification of brain tissue abnormalities in patients with large vessel occlusion acute ischemic stroke (AIS). Methods: We retrospectively included a series of patients with large vessel occlusion AIS comprising the middle cerebral artery (MCA) territory. All patients underwent non-contrast brain computed tomography (CT) and CT angiography using a dual-layer spectral CT scanner. Using a multiparameter display including conventional CT images (Hounsfield units, HU), ED relative to water (%EDW), and effective atomic number (Zeff), we evaluated the brain tissue territory distal to the occlusion, and the contralateral hemisphere. Results: Twenty-eight patients were included, with a mean age of 75.7 ± 10.9 years. The brain tissue distal to the MCA occlusion showed significant differences compared with the contralateral hemisphere only using conventional CT (25.0 ± 2.7 HU vs. 29.2 ± 2.4 HU, p < 0.0001) and ED imaging (102.2 ± 0.3 %EDW vs. 102.6 ± 0.2 %EDW, p < 0.0001), whereas the Zeff (7.37 ± 0.1 vs. 7.37 ± 0.1, p = 0.36) showed similar values. ED imaging was associated with a significantly higher diagnostic confidence for the identification of abnormal findings, both for the evaluation of the hyperdense MCA (conventional CT 3.46 ± 1.3 vs. ED imaging 4.79 ± 0.4 vs. Zeff imaging 2.07 ± 1.0, p < 0.0001) as well as for the subtended brain parenchyma (conventional CT 3.30 ± 1.3 vs. ED imaging 4.30 ± 0.8 vs. Zeff 1.44 ± 0.6, p < 0.0001). Conclusions: In this study, ED imaging enabled a more confident identification of brain tissue changes related to large vessel occlusion AIS compared with conventional CT imaging.