Noncontrast Computed Tomography Markers of Intracerebral Hemorrhage Expansion
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Spontaneous intracerebral hemorrhage (ICH) is a common and ominous consequence of cerebral small vessel disease. It is now known to be a dynamic disease, with up to one third of patients experiencing continued bleeding after initial presentation.1 This growth, also termed hematoma expansion is an independent predictor of early neurological deterioration and worse long-term outcome and represents an appealing therapeutic target.2 Early identification of patients at high risk of ICH expansion is, therefore, crucial to target therapies to those likeliest to expand.3 The presence of active contrast extravasation within the hematoma, also known as the spot sign, is a validated imaging marker of hematoma expansion.4 However, this sign has a limited sensitivity for expansion.5,6 Furthermore, the identification of the spot sign requires computed tomography angiography (CTA), with potential drawbacks including additional radiation delivery. Several noncontrast CT (NCCT) biomarkers have been studied since the early 1980s and have recently gained attention as promising predictors of ICH expansion.7–11
Unlike CTA, NCCT is almost universally performed to diagnose ICH in the emergency department. NCCT biomarkers have the potential to become an inexpensive and readily available tool to stratify the risk of hematoma growth in clinical practice and for clinical trials. In this review, we summarize the current evidence on spontaneous ICH expansion prediction using NCCT and aim at paving the way toward a standardization of NCCT biomarker nomenclature.
Hemorrhage Formation, Expansion, and Its NCCT Appearance
Initial Hemorrhage Formation
The imaging appearance of an acute ICH varies by many biological factors, including the patient’s hematocrit and the intrahemorrhage protein concentration.12 It is constantly though characterized by the presence of a spontaneously hyperattenuating area within the brain parenchyma, explained by the relative higher attenuation of fresh blood by comparison to the surrounding brain tissue.12,13 The higher attenuation of recent blood has …