Calcification of chronic subdural haematoma is called "armoured brain" when it 
covers most of the cortical surface. We report high-field magnetic resonance 
images of the armoured brain, and discuss the relationship between operative 
findings, computer assisted tomographic (CT) findings and the change in 
relaxation time on magnetic resonance images. In our case, low, iso, and high 
density layers were detected on computer assisted tomography. The change in 
relaxation time of a liquefied haematoma showed good agreement with 
chronological change in intracerebral haematoma, and the material was easily 
detected on magnetic resonance images. But with a grainy and mud-like haematoma, 
the change in relaxation time did not coincide with the state of the 
intracerebral haematoma. It is generally said that in the detection of a 
calcified mass, computer assisted tomography is superior to magnetic resonance 
images and this was also true in the present case. While there are a few reports 
on computer assisted tomographic findings for the armoured brain, this is 
probably the first report on high-field (1.5T) magnetic resonance imaging of the 
armoured brain.