Fig. 1
From: Spectrum of MRI features of ganglion and synovial cysts
a-c. Lumbar facet synovial cyst in an 82-year-old woman presenting with subacute left lumbar radiculopathy and neurogenic claudication. Sagittal T2-weighted MRI (a) shows a slightly hyperintense cystic lesion posteriorly to the L3/L4 disc (arrow), as well as grade 1 degenerative spondylolisthesis at L4/L5. The axial view (b) clearly demonstrates the extradural location of the lesion (dashed arrow) arising from the left L3/L4 degenerated facet joint, which presents synovial effusion (asterisk). Note in both axial and coronal (c) views the displacement of the thecal sac and the left L4 nerve root (arrows) toward the right, due to compression by the cyst (dashed arrows). The partial T2-hypointensity, more evident in image c, might correspond to high-protein content or previous internal bleeding