Following head trauma, CT is usually performed if clinical conditions merit imaging. The major concern is always blood, in particular abnormalities amendable to outcome influencing surgical procedures. This particularly relates to extra-axial collections - extradural and subdural hematomas.

How does one know which is which? The answer is fruity! The shape is usually the key:

• extra-dural hematoma is lentiform like a lemon
• subdural hematoma is sickle shaped like a banana

Image with thanks to Dr I Waldron, Consultant Radiologist, Doncaster Royal Infirmary, UK.