MRI thresholds for discrimination between normal and mild temporomandibular joint involvement in juvenile idiopathic arthritis

Abstract

BackgroundCurrently there is no consensus agreement on the degree of enhancement in normal temporomandibular joints (TMJ) in children, which makes it difficult for clinicians to distinguish between the presence/absence of mild synovitis. Quantitative measurements of synovial and condylar enhancement may be useful additions to current qualitative methods on early MRI diagnosis and follow up of TMJ involvement in JIA. The purpose of the study is to establish thresholds/tendencies for quantitative measures that enable distinction between mild TMJ involvement and normal TMJ appearance based on the degree of synovial and bone marrow enhancement in JIA patients.MethodsTMJ MRI examinations in 67 children with JIA and in 24 non-rheumatologic children who underwent MRI for neurologic/orbit indications were retrospectively assessed. As a priori determined TMJs of JIA patients were categorized into three groups by experienced staff radiologists based on the degree of synovial and condylar enhancement: no active disease (rheumatologic control), mild and moderate/severe findings. The signal intensity (SI) of the synovial tissue around each condyle and of the bone marrow was measured to calculate the enhancement ratio (ER) and relative SI change. The ER was calculated using signal to noise ratios, while relative SI change was calculated using signal intensities alone. Quantitative measurements of synovial and condylar enhancement of TMJs with mild or moderate/severe findings were compared with the rheumatologic and non-rheumatologic controls.ResultsMean ER values were significantly different between the TMJs without active disease and those with mild and moderate/severe synovial enhancement, with highest values in the moderate/severe group (P < 0.0001). Similar findings were seen for condylar enhancement with P < 0.005. Relative SI change was unable to differentiate TMJs with mild synovitis from the two controls (P > 0.10). 27/60 (45 %) TMJs without active disease had osteochondral changes. 8/40 (20 %) TMJs in the mild group did not demonstrate any synovial thickening.ConclusionsQuantitative signal to noise ratios of TMJ synovial and condylar enhancement generate thresholds/tendencies, which offer additional information to differentiate mild synovitis from normal TMJs in JIA patients. Osteochondral changes and synovial thickening may not be reliable indicators of active TMJ involvement and should be differentiated from synovial enhancement.

Normal magnetic resonance appearances of the temporomandibular joints in children and young adults aged 2–18 years

“…Our results are also supported by two other recent publications; in 46 children without TMJ disease von Kalle and colleagues [21]showed 73% (23, 123) mean increase in signal intensity in synovial tissue while Ma and co-workers [22] showed 66% (40, 92) mean increase in 24 children without rheumatologic disease.…”

“…The precision of assessing contrast enhancement of the TMJs in healthy children has been addressed in a few studies [21,22]. In a study of 100 contrast We found that the condylar inclination in the sagittal/oblique plane increased by age, and that 60% of children under the age of ten had straight condyles while the majority of those aged 17-18 years had marked anterior inclination.…”

“…Moreover, recent studies have addressed the ability of MRI to diagnose active TMJ disease in children with JIA, as findings suggestive of inflammation have been reported in healthy children without JIA [14,17,20,21]. Some of the studies evaluate contrast enhancement [14,[21][22][23] and others bone marrow edema-like changes [14,17,20]. In their study on 46 children who had a total of 100 contrast MRIs of the brain, von Kalle and co-workers also discussed the complexity of contrast enhancement, underpinning the importance of correct measurements and timing of the post-contrast images.…”

Optimization of Quantitative Dynamic Postgadolinium MRI Technique Using Normalized Ratios for the Evaluation of Temporomandibular Joint Synovitis in Patients with Juvenile Idiopathic Arthritis

“…4 While many prior MR imaging approaches have relied on subjective interpretation of synovial enhancement more recently, attempts have been made to assess the utility of quantitative analysis of TMJ synovial enhancements. [5][6][7][8] Peacock et al 6 defined a ratio of the TMJ synovial postgadolinium signal inten-sity normalized to the longus capitis muscle in control patients and found a 95% specificity threshold of 1.55. Resnick et al 8 found that the 1.55 threshold had a 91% sensitivity and 96% specificity for detecting synovitis in symptomatic JIA TMJs.…”

Quantifying Temporomandibular Joint Synovitis in Children With Juvenile Idiopathic Arthritis

“…However, measurement of synovial thickness in a small joint with 2 compartments and overlap of the disc and surrounding soft tissues is technically challenging, and the chronicity of disease implied by the presence of thickened synovium is unclear. Ma et al found that 20% of TMJs that had mild synovitis did not demonstrate hypertrophy of the synovium, and determined that synovial thickening was not a reliable marker for disease .…”