pedicles provide a clue to the presence of a space-occupying lesion. CT scans, especially bone windows, may show enlarged neural foraminae or sacral spinal canal. Soft tissue windows may show a mass with the same density as the CSF. The mass does not enhance with contrast. MRI studies easily detect the cysts and clearly show their size and location. The sagittal cuts will show a pea-sized or larger mass that is isointense with the CSF and is located at the end of the thecal sac in the sacral region. The cysts are usually hyperintense in T2-weighted images and remain so following fat suppression. Unlike metastatic disease or primary nerve root tumors, perineural cysts do not enhance with contrast (Figures 7-3A, 7-3B, and 7-3C).
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