FIG 2. Axial dynamic CT myelogram at the level of the T7–T8 interspace in the left lateral decubitus (A), right lateral decubitus (B), supine (C), and prone (D) positions demonstrates accumulation of extra-arachnoid contrast material along the ventral right aspect of the thecal sac, which increases in attenuation in the right lateral decubitus positioning (open arrows). The final prone images, which were obtained 30 minutes after injection of contrast, demonstrate dilution of contrast material in the previously unopacified epidural fluid collection and outlines the underlying T7 disk protrusion (black arrow)