Safety and technical performance of bilateral decubitus CT myelography using standard versus increased intrathecal iodinated contrast volume.

Background and purpose: Lateral decubitus CT myelography (LDCTM) is one of the main studies for the detection of CSF-venous fistulas (CVF), but detection of CVFs is dependent on intrathecal contrast density. The purpose of this investigation was to assess tolerability and technical performance of increased intrathecal doses of myelographic contrast compared to standard doses.

Materials and methods: Retrospective series of 24 patients who underwent LDCTM following administration of either 10 or 20 ml of intrathecal iodinated contrast media (300 or 320mg/mL iodine content). Patients were scanned in the initial lateral decubitus position, then turned to the contralateral side and re-scanned in the same session. Safety and tolerability of the 20 ml dosage was assessed from clinical records. Technical performance of the studies was compared between groups by measuring attenuation values over the lateral thecal sac at standardized levels. Both the initial scan and the scan after turning to the contralateral side were assessed.

Results: No moderate or severe adverse event was recorded in either group. The 20-ml group showed higher attenuation values, which were statistically greater on the second side examined compared to the standard-dose group.

Conclusions: Increased volume of intrathecal contrast was well-tolerated and improved technical performance of LDCTM in this limited series. Further assessment of safety and impact on diagnostic yield using larger patient cohorts is warranted.

Abbreviations: LDCTM = lateral decubitus CT myelography; CVF = CSF-venous fistula; IOCM = iodinated contrast media.