2012 Radiology Exam - Spec Proced/NM Case 1

Signalment: 9-year old MC Pug

History: 12 month history of progressive hind limb ataxia.

Imaging Studies: 3 lateral views and 3 VD views of a thoracolumbar myelogram were provided to the candidate.


  • Lateral views: Attenuation of both contrast columns over vertebral body T12. Bulbous widening of dorsal contrast column dorsal to caudal T12 – T13 vertebral bodies. (Mild dorsal deviation of ventral contrast column over several intervertebral disc spaces).
  • Ventrodorsal views: Bulbous widening (“teardrop shape”) of left contrast column over caudal half of T12 vertebra; attenuation of contrast columns cranially. Spinal cord compressed and displaced to the right.


  • Subarachnoid cyst/diverticulum at T12 (left-sided and dorsal) resulting in spinal cord compression; (incidental multifocal disc bulges).

Case Management

  • Surgery to decompress spinal cord (Candidates did not lose points if additional imaging such as CT was recommended prior to surgery, but ultimate recommendation should have been surgery).


  • Inability to determine location of lesion (intramedullary vs. intradural-extramedullary vs. extradural).
  • Inability to recognize that lesion represents dilation of subarachnoid space rather than an intradural-extramedullary mass.
  • Failure to recommend surgical decompression due to compressive nature of the lesion.