What CT features distinguish an epidural hematoma from a subdural hematoma?

• A. Epidural hematoma is crescent-shaped and can cross sutures.
• B. Epidural hematoma is biconvex and does not cross sutures.
• C. Subdural hematoma is crescent-shaped and cannot cross sutures.
• D. Subdural hematoma is ring-shaped.

Answer: (B)

The key idea is how the hematoma sits relative to the skull and dura, which shapes what you see on CT. An epidural hematoma forms between the skull and the dura and usually appears as a biconvex, lens-shaped collection. Its growth is limited by the sutures because the dura is tightly attached there, so it does not cross cranial sutures. A subdural hematoma, by contrast, lies between the dura and arachnoid and follows the surface of the brain, producing a crescent-shaped collection that can extend across sutures. Ring-shaped appearances aren’t typical for acute traumatic hematomas on CT, so they don’t fit as well.