When does CT myelography add value beyond MRI for lumbar degenerative disease?

Area of Science:

• Neurosurgery
• Radiology
• Spine Surgery

Background:

• Lumbar spinal stenosis diagnosis requires identifying all symptomatic levels.
• CT myelography shows higher sensitivity (94.4%) for stenosis than MRI (75.9%).
• The utility of invasive CT myelography in specific patient subgroups remains unclear.

Purpose of the Study:

• To identify patient subgroups with lumbar stenosis who may benefit from CT myelography after an initial MRI scan.
• To determine if CT myelography provides additional diagnostic information in specific patient populations.

Main Methods:

• Retrospective chart review of patients (>45 years) with lumbar degenerative disease.
• Analysis of MRI and CT myelography scans within 6 months, assessing stenosis severity (mild, moderate, severe) at each lumbar level.
• Fisher exact test used to compare the change in stenosis severity between MRI and CT myelography.

Main Results:

• CT myelography identified more additional stenotic levels in patients with multilevel stenosis (58%) compared to single-level stenosis (40%, p=.018).
• In patients with no moderate-to-severe stenosis on MRI (n=62), CT myelography identified only 5% additional stenotic levels (p=.836).
• CT myelography was significantly more beneficial for patients with multilevel stenosis.

Conclusions:

• CT myelography is most valuable for patients with multilevel lumbar spinal stenosis.
• Its utility is limited in patients with no or single-level stenosis identified on initial MRI.
• This finding helps guide judicious use of invasive CT myelography.