Defining the CT Angiography 'Spot Sign' in Primary Intracerebral Hemorrhage

Purpose: The computed tomogram angiography (CTA) 'spot sign' describes foci of intralesional enhancement associated with hematoma expansion in primary intracerebral hemorrhage patients. A consistent radiological definition is required for two proposed recombinant Factor VIIa trials planning patient dichotomization according to 'spot sign' presence or absence. We propose radiological criteria for diagnosis of the CTA 'spot sign' and describe different morphological patterns. Material and Methods: A prospective cohort of 36 consecutive patients presenting with primary intracerebral hemorrhage (ICH) were enrolled in a multicenter collaborative study, and have been included for the present analysis. Three reviewers analyzed the CTA studies in a blinded protocol. Analysis of specific ICH and 'spot sign' features was performed including prevalence, number, size, location, morphology and Hounsfield unit density. Results: Twelve of thirty-six patients (33%) demonstrated a total of 19 enhancing foci consistent with the CTA 'spot sign'. Mean maximal axial 'spot sign' dimension was 3.7 +/- 2.2 mm and mean density was 216 +/- 57.7 HU. No significant differences in age or blood pressure (p=0.7), glucose (p=0.9), INR/PTT (p=0.3 and 0.4) or hematoma location (p=0.3) were demonstrated between patients with or without the 'spot sign'. Consensus definition and classification criteria for the CTA 'spot sign' are proposed. Conclusion: The 'spot sign' is defined as spot-like and/or serpiginous foci of enhancement, within the margin of a parenchymal hematoma without connection to outside vessels. The 'spot sign' is greater than 1.5 mm in maximal dimension and has a Hounsfield unit density at least double that of background hematoma density.