Marked increase in fat in the epidural space (Green arrows) with the thecal sac compressed into a characteristic trefoil shape (Pink arrow).
The trefoil appearance of the thecal is a very characteristic appearance in the lumbar spine with epidural lipomatosis.
However this appearance is not seen in the thoracic spine where there will just be excess epidural fat.
In the cervical spine epidural lipomatosis is not seen.