Pottt's spine with bilateral psoas abscess - MRI

Sagittal T2 and T1 images of MRI lumbar spine in 20 year old male showing partial collapse of the L4 vertebral body with restropulsion of the posterior fragment causing thecal sac compression and mild compression on the traversing nerve roots. 

Axial T2 image at the level of L4 showing bilateral large psoas abscesses.

Coronal image well depict the craniocaudal extent of the abscess.

Lipoma of the Filum Terminale

T1 sagittal image of the lumbar spine showing multiple osteoporotic collapsed vertebral bodies with elongated linier  wavy hyperintense intraspinal structure from the level of L2 to S1 consistent with filum terminale lipoma.

Axial T1 weighted image showing filum terminale lipoma as small intraspinal hyperintense dot (arrow).

Discussion:

Fat in the filum terminale is not an infrequent occurence, seen in 4 – 6%, and is usually easily detected on MRI (especially T1 sequences). It is usually an incidental finding of no clinical concern.
In some individuals however it is associated with spinal dysraphism, thickening of the filum terminale (>3mm) and tethering of the spinal cord.
Classification: Four patterns: 

1) fatty filum with descended conus medullaris and symptoms.

2) fatty filum with descended conus medullaris and no symptoms.

3) fatty filum with normal conus medullaris position and symptoms.

4) fatty filum with normal conus medullaris position and no symptoms

Imaging findings:

CT scan: If the lesion is large, seen as hypodense focus (fat density HU -90 to -30) below the level of conus. If it is  small may not be visible.

MRI: is modality of choice.

• Hyperintense on T1 and T2 FSE
• Saturates on fat saturation sequences
• Demonstrates chemical shift artefact
• No enhancement.

References
1. E Brown et al “Prevalence of incidental intraspinal lipoma of the lumbosacral spine as determined by MRI.” Spine. 1994 Apr 1;19(7):833-6.
2. K Koeller et al “Neoplasms of the Spinal Cord and Filum Terminale: Radiologic-Pathologic Correlation” RadioGraphics 2000; 20: 1721-1749.

Tarlov Cyst

25 year old young male came with radicular pain to lower limb on right side referred for MRI LS spine. MRI T2 weighted para saggital image shows well defined rounded hyperintense lesion in the D12-L1 intervertebral foramen causing compression on the exiting nerve root on right side. CISS 3D axial image shows the lesion better (arrow).

Tarlov or perineurial cysts are pathological formations located in the space between the peri-and endoneurium of the spinal posterior nerve root sheath. Tarlov cysts are rare causes of low back pain. They are more common in females. Clinical presentation of Tarlov cysts is variable. The cysts may cause local and/or radicular pain. Depending on their location, size and relationship to the nerve roots, they may cause sensory disturbances or motor deficits to the point of bladder dysfunction.

Radiograph is usually normal, it may show bony erosion or widening of foramen on oblique views. Conventional myelography may show extradural indentation on the thecal sac however MRI is needed for confirmation of the lesion. CT scan can demonstrate cystic lesion isodense with CSF located at the foramina. Bony changes may also be present. MRI shows welldefined CSF intensity lesion in the prineural location predominantly in lumbar and sacral region. The lesions may be seen in the cauda equina and other nerve roots.