What does a non-contrast head CT primarily rule out?

A non-contrast head CT is particularly valuable in the evaluation of patients with neurological symptoms because it is highly sensitive for detecting acute intracranial hemorrhages. This imaging modality allows for the quick identification of bleeding in the brain such as subdural hematomas, epidural hematomas, and intracerebral hemorrhages. In emergency situations, where rapid assessment and intervention may be necessary, ruling out hemorrhage is critical, as the management may differ significantly based on the presence or absence of such conditions.

While non-contrast head CT can identify some types of tumors, infections, and bone fractures, it may not be as definitive for these conditions compared to its efficacy in detecting hemorrhages. Tumors often require additional imaging studies (such as MRI) for better characterization, and infections (like abscesses) may not be as easily distinguished without contrast. Bone fractures, particularly of the skull, can sometimes be better visualized with dedicated skeletal imaging or contrast. Thus, the primary role of a non-contrast head CT is to rule out hemorrhagic events, making it an essential tool in acute neurological assessments.