The curtain sign (or draped curtain sign) in neuroimaging refers to the appearance of a vertebral body mass that extends to the anterior epidural space.
The posterior longitudinal ligament is strongly attached to the posterior vertebral body cortex in the midline and is more loosely attached laterally.
If a vertebral body lesion (e.g. vertebral metastasis, vertebral hemangioma) extends posteriorly to the anterior epidural space, it displaces the posterior longitudinal ligament. However this is limited by that strong medial fixation, giving a bilobular intracanalar aspect in the axial images, which is commonly called curtain sign (or draped curtain sign).
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