CT Scan Brain Normal Vs Hemorrhagic Stroke Images | Swirl, Black Hole, Blend, Spot & Island Signs

CT Scan Brain Normal Vs Hemorrhagic Stroke Images | Swirl, Black Hole, Blend, Spot & Island Signs

*Cases
Hyperdense Area - 0:00
Swirl Sign - 1:31
Black Hole Sign - 5:38
Blend Sign - 7:04
Satellite Sign - 8:13
Spot Sign - 9:23
Island Sign - 10:55

- Hyperdense Area: The most characteristic feature of an acute hemorrhagic stroke on a non-contrast CT scan is a hyperdense (bright) area within the brain parenchyma. This is due to the high attenuation of acute blood compared to brain tissue.

- Surrounding Edema: As the hemorrhage evolves, surrounding low-density edema may develop, usually becoming more evident a few days after the onset. This edema can further contribute to the mass effect.

Swirl Sign: Characterized by areas of mixed density within a hemorrhagic lesion. It shows a combination of hyperdense (bright) and hypodense (darker) areas within the hemorrhage, giving the appearance of a swirling pattern of blood at different stages of clotting. The swirl sign is often associated with a larger volume of hemorrhage, potential for hemorrhage expansion, and increased intracranial pressure due to the mass effect of the accumulating blood. Patients with this sign on their initial CT scan may have a higher risk of deterioration and poor outcomes compared to those without the sign.

Mass Effect: Distortion, compression, or obliteration of the brain's ventricles and sulci near the site of the hemorrhage. This effect results from the volume of blood accumulating within the brain parenchyma, which increases intracranial pressure and compresses adjacent brain tissue.

Black Hole Sign: Relatively hypodense (darker) area within the hyperdense (bright) hemorrhagic lesion, often round or oval in shape. This dark area is surrounded by the brighter areas of acute hemorrhage, resembling a "black hole." Black hole sign and hemorrhage must have a difference of at least 28 Hounsfield Unit.

Blend Sign: Mixed density hematoma consisting of a hyperdense area adjacent to a hypodense area. Well-defined border/interface between the hyperdense and hypodense areas. These two regions must have a difference of at least 18 HU.

Satellite Sign: Small hyperdense area that is separate from the main hematoma. Should be less than 10mm in diameter. Distance between main hematoma and satellite sign should not be greater than 20mm. Must not be present in subarachnoid space or ventricles.

Spot Sign: One or more spots of contrast enhancement within an area of acute intracerebral hemorrhage on CTA scans. These spots are seen during the arterial phase of contrast administration, indicating active bleeding within the hematoma.
- Attenuation greater than twice that of the hemorrhage
- Radiodensity = 120HU

Island Sign: 3 or more small hematomas separate from the primary hematoma.

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