Facet arthropathy evaluation: CT or MRI?

Area of Science:

• Radiology
• Spine Imaging
• Osteoarthritis

Background:

• Lumbar facet arthropathy (FA) evaluation is critical for diagnosing back pain.
• The presence of lumbar disc prosthesis can complicate imaging assessment.
• Reliability of CT and MRI in assessing FA requires further investigation.

Purpose of the Study:

• To assess the interobserver reliability of CT and MRI for evaluating lumbar facet arthropathy.
• To compare reliability in patients with and without lumbar disc prosthesis.
• To estimate reliability for individual CT and MRI findings of facet arthropathy.

Main Methods:

• 114 chronic back pain patients (with/without lumbar disc prosthesis) underwent metal-artifact reducing CT and MRI.
• Three radiologists independently rated facet joint space narrowing, osteophyte/hypertrophy, erosions, subchondral cysts, and total grade FA.
• Interobserver agreement was assessed using kappa statistics, including prevalence- and bias-adjusted kappa.

Main Results:

• Moderate interobserver agreement for total grade FA with CT (kappa 0.47-0.48), poor to fair with MRI (kappa 0.20-0.32).
• Agreement was higher for CT than MRI for osteophyte/hypertrophy and total grade FA.
• Disc prosthesis presence did not significantly influence agreement; agreement was poorer for osteophyte/hypertrophy grading.

Conclusions:

• Interobserver agreement for lumbar facet arthropathy is moderate with CT and better than with MRI.
• Lumbar disc prosthesis does not affect agreement reliability.
• Improved grading of facet arthropathy necessitates more consistent evaluation of osteophytes/hypertrophy.