Lumbar juxtafacet cyst MRI
MRI: variable findings (may be due to differing composition of cyst fluid: serous vs. proteinaceous 1). Unenhanced signal characteristics of non-hemorrhagic JFC may be similar to CSF. Hemorrhagic JFC is hyperintense. MRI usually misses bony erosion.
This entity cannot be reliably distinguished from ganglion cyst on standard MRI. However, communication with the joint space after intra-articular injection with contrast reliably differentiates the two.
Gas within the cyst is pathognomonic for a synovial cyst
Facet joint cysts may contain complex fluid as a result of internal debris or haemorrhage
Neural based cysts can usually be differentiated by imaging as these cysts show intimate relation with the adjacent nerve, rather than with the adjacent joint space
Calcification within cyst wall appears low signal intensity on both T1 and T2 weighted images whereas haemorrhagic cysts display increase intensity compared to CSF likely due to T1 shortening from methaemoglobin.
The cysts do not always possess the signal characteristics of a simple cyst, so contrast administration may be needed in some cases. It is important to remember that they are a cause of peripherally enhancing masses in the extrathecal space anywhere along the spinal canal.