Rookies Quiz 3

Scan reveals effaced (compressed) sulci and cisterns suggestive of cerebral edema. High attenuation areas are seen in the sylvian fissures suggestive of blood. No fracture is seen in the presented pictures.

Sub arachnoid hemorrhage with cerebral edema

Blood is immediately picked up on CT (HU values are above 50), as compared to any other modalities, including MR imaging. CT is thus the most common radiological examination technique in the emergency management of head injuries. The equipment is widely available and examination is quick, has high sensitivity for fresh bleeding and can reveal edema. It can also show raised intra-cranial tension in the form of compressed sulci and ventricles. It readily detects fractures and whether they are displaced or not. CT has indeed markedly improved the potential to treat and care for patients with head injuries.

MRI has certain limitations in head injuries- there may be difficulty in detecting fresh bleeding, and subarachnoid hemorrhage may go undetected, the time span taken is much longer compared to a CT scan examination, and also life-saving equipment cannot be used for the patient due to magnetic effect.

MR imaging is better in follow up scan for head injuries and also in detecting axonal injuries (shearing injuries) which occur in vehicular accidents due to sudden deceleration. This condition may go undetected on CT examination if no bleeding component is seen.