MRI Assessment of Sacroiliitis With High-Resolution Protocol

Area of Science:

• Radiology
• Rheumatology
• Orthopedics

Background:

• Sacroiliac (SI) joint subchondral resorption on high-resolution MRI may indicate early sacroiliitis.
• Current institutional practice uses specific MRI sequences for suspected spondyloarthritis (SpA) workup.

Purpose of the Study:

• To evaluate if SI joint subchondral resorption is a useful MRI feature for diagnosing sacroiliitis.
• To test the hypothesis that this imaging finding aids in SpA diagnosis.

Main Methods:

• Retrospective review of patients with suspected SpA undergoing SI joint MRI.
• Analysis of MRI features, including subchondral resorption, against clinical diagnosis.
• Bayesian latent class modeling to estimate sensitivity and specificity.

Main Results:

• SI joint subchondral resorption strongly correlated with a positive diagnosis in patients evaluated for axial SpA.
• This feature showed higher sensitivity than bone marrow edema, erosion, or ankylosis for sacroiliitis detection.
• High interobserver reliability was observed for identifying subchondral resorption.

Conclusions:

• Subchondral resorption on SI joint MRI is a sensitive indicator for SpA, potentially reflecting early disease.
• This imaging finding warrants further validation in diverse patient cohorts with suspected axial SpA.