Head CT will provide the diagnosis of ICH in the ED. Noncontrast head CT can be performed rapidly, and, in many centers, without the patient needing to leave the ED. Although magnetic resonance imaging (MRI) is more sensitive in detecting acute ischemia, it has capability similar to CT in detecting ICH.72 Examples of head CTs scans demonstrating ICH are shown in Figure 1 through Figure 5. Both blood and bone appear hyperdense on CT. However, their appearance can be distinguished by utilizing Hounsfield units (HUs). The HU scale is a method to measure radiodensity by comparing the image to the radiodensity of distilled water at a standardized pressure and temperature. Bone is > 400 HUs, whereas blood is 30 to 45 HUs.73
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