====== Arachnoiditis ossificans ======

A rare condition (only ≈ 43 case reports as of 1998
((Lucchesi AC, White WL, Heiserman JE, et al. Review
of Arachnoiditis Ossificans with a Case Report. BNI
Quarterly. 1998; 14:4–9))) involving calcification of the arachnoid membrane. In the T-spine, may occur as ossified plaques or in a cylindrical form surrounding the spinal cord. May be difficult to detect on MRI and myelography. 

Plain
unenhanced CT may be optimal for diagnosis