Imaging of the temporomandibular joint in juvenile idiopathic arthritis: How does quantitative compare to semi-quantitative MRI scoring?

Publication date: Available online 11 December 2018

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Grace MY. Ma, Carly E. Calabrese, Timothy Donohue, Zachary S. Peacock, Paul Caruso, Leonard B. Kaban, Cory M. Resnick

Abstract

Purpose

Contrast-enhanced MRI is commonly used to evaluate temporomandibular joint (TMJ) disease in patients with juvenile idiopathic arthritis (JIA). However, MRI assessment is limited by qualitative reporting, presence of enhancement in normal joints, and lack of standardized protocols. The purpose of this study is to compare a quantitative MRI analysis, enhancement ratio (ER), to a new semi-quantitative system developed by OMERACT (Outcome Measures in Rheumatology and Clinical Trials).

Materials and Methods

Retrospective cross-sectional study including children with JIA who had TMJ MRIs with gadolinium at Boston Children's Hospital. Predictor variables included: demographic (sex, age at MRI), and disease related findings (JIA subtype and arthritis medication at time of MRI). Outcome variables were OMERACT scores and ER (ratio of TMJ synovium and longus capitis muscle pixel intensities). ER was compared to OMERACT total (T), inflammatory (I), and damage (D) scores using Pearson's correlation analysis and multivariable linear regression. Statistic significance was evaluated with Student's t-test and analysis of variance with significance set at p<0.05. Inter- and intra-examiner reliability were evaluated using intraclass correlation coefficients.

Results

Sample included 50 subjects (84% female) with mean age 12.7±3.9 years and 124 MRIs. Mean ER=2.5±0.9 (normal <1.55). Mean OMERACT T was 4.9±3.3. Controlling for age, sex, JIA subtype, and medications, for every 1 unit increase in ER, OMERACT increased by: 3.11 for T (p<0.001), 1.01 for I (p<0.001), and 0.86 for D (p<0.001). Intra- and inter-rater consistency was better for ER (ICC=0.83 and 0.96) than OMERACT (ICC=0.77 and 0.35).

Conclusion

Quantitative evaluation of TMJ synovial enhancement (ER) is easier to score and has superior intra-and inter-rater agreement, but only assesses inflammation, while semi-quantitative assessment of TMJ (OMERACT) adds data about chronic changes. A combination of these systems may provide the most accurate assessment of JIA status.

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