PMC9085244_01
(A-C) Maximum intensity projection, MRI and PET-MR fusion images at the level of L3-L4, separately. (D-F) Maximum intensity projection, MRI and PET-MR fusion images at the level of L5-S1, separately. Fat-suppression T1-weighted sequences in the axial plane without contrast showing increased and homogeneous intensity within the epidural space [arrowheads in panels (B,E)], indicative of extensive scar formation. The fusion images [arrowheads in panels (C,F)] reveal mild FDG uptake in the epidural scar with SUVmax of 2.0. The epidural fibrosis encircles the right L4 root [arrow in panel (C)] and right S1 root [arrow in panel (F)]. The FDG uptake of the right L4 root is similar to that of the adjacent epidural scar, while the right S1 root shows intense FDG uptake with SUVmax of 4.2.
fmed-09-860545-g001.jpg
PMC9085244_01_fmed-09-860545-g001.jpg
F1
The tentative diagnosis was entrapment neuropathy secondary to epidural fibrosis (Figure 1).
CT-guided transforaminal injection at the level of L5-S1. Axial CT for the extent of contrast spread. (A) Visualization of the needle in the epidural space (arrowheads) and the dye (thick arrow) blocked by the scar. (B) Contrast filling around the right S1 root (thick arrow) at the ventral epidural space.
fmed-09-860545-g002.jpg
PMC9085244_01_fmed-09-860545-g002.jpg
F2
We arranged CT-guided transforaminal injection of a lidocaine and contrast dye mixed injectate for the pre-operative diagnosis of right s1 root entrapment by an epidural scar (Figure 2).