NYMC Faculty Publications

The Delayed Spectral Sign in Post-Transfer CT Imaging: An Imaging Marker of Stroke Severity and Hemorrhagic Risk

DOI

10.1007/s00234-025-03718-7

Journal Title

Neuroradiology

First Page

2349

Last Page

2356

Document Type

Article

Publication Date

9-1-2025

Department

Radiology

Second Department

Neurosurgery

Third Department

Neurology

Keywords

Intracranial hemorrhage, Large vessel occlusion, Residual contrast, Spectral CT, Stroke

Disciplines

Medicine and Health Sciences

Abstract

Purpose: Acute stroke transfer patients often undergo repeat computed tomography (CT) imaging upon arrival at a thrombectomy-capable center. Often, there is residual intravenous (IV) “contrast staining” of acute infarcts on the initial post-transfer CT head exam, which we have detected utilizing dual-layer CT spectral virtual non-contrast images. We term this the delayed spectral sign (DSS). We sought to measure the incidence of the DSS on initial post-transfer CT head exams and evaluate for any associated clinical outcomes. Methods: We performed a retrospective study of acute stroke transfer patients with residual IV contrast on initial post-transfer CT spectral scanner head exams. Two neuroradiologists independently reviewed CT head exams and virtual non-contrast images to measure the incidence of the DSS. Data was analyzed to evaluate significant differences between DSS and non-DSS groups. Results: 67 acute stroke transfer patients met inclusion criteria, of whom 8 (11.9%) demonstrated the DSS. Patients with the DSS were more likely to have a large vessel occlusion (100% vs. 64.4%, P = 0.049) and an M1 middle cerebral artery (MCA) occlusion (OR 4.9, P = 0.046). DSS patients had a greater prevalence of intracranial hemorrhage on follow-up CT or magnetic resonance imaging (MRI) exams (OR 9.259, P = 0.008). DSS patients had a higher average National Institute of Health Stroke Scale (NIHSS) upon discharge (22.25 ± 18.3), although this was not statistically significant (P = 0.079). In multivariate regression analyses, DSS was positively associated with intracranial hemorrhage on inpatient follow-up CT or MRI (OR 9.683, P = 0.012). Conclusion: The delayed spectral sign is associated with greater incidences of large vessel occlusions and intracranial hemorrhage on follow-up head imaging.

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