Pannus / Retroodontoid pseudotumor


Retro-odontoid pseudotumors or pannus are deposits – mostly in the area behind the dens – resulting from instability. It is an indirect sign of instability.

There are different biochemical structures which form a pannus:

– Micro- hemorrhages
– ossification
– Deposits of calcium pyrophosphate dihydrate (crowned dens syndrome)

Depending on how the pannus is built it is shown at different sequences in the MRI.