MRI assessment of bone marrow in children with juvenile idiopathic arthritis: intra- and inter-observer variability

Area of Science:

• Pediatric Rheumatology
• Radiology
• Medical Imaging

Background:

• Bone marrow oedema (BMO) is a key indicator of disease activity in adult rheumatoid arthritis using MRI.
• Current MRI-based scoring systems lack specific criteria for juvenile idiopathic arthritis (JIA).

Purpose of the Study:

• To evaluate the multi-center reproducibility of an MRI-based bone marrow oedema (BMO) scoring system in pediatric patients with JIA.
• To establish a reliable method for assessing disease activity in JIA using MRI.

Main Methods:

• Seventy-six wrist MRIs from children with JIA were independently reviewed twice by two experienced pediatric radiologists.
• Bone marrow oedema (BMO) was defined by specific signal characteristics on T2- and T1-weighted images.
• BMO extent was scored on a 0-3 scale for 14 wrist bones.

Main Results:

• Intra-observer agreement for the BMO scoring system was moderate to excellent (kappa: 0.49-1.0).
• Inter-observer agreement showed a range of 0.41-0.79.
• Intraclass correlation coefficients indicated excellent intra-observer and satisfactory inter-observer reliability.

Conclusions:

• The developed MRI BMO scoring system demonstrates reliability for grading bone marrow abnormalities in JIA.
• The observed variability, especially between readers, highlights the necessity for comprehensive standardization of the scoring system.