Evaluation of enthesitis in patients with juvenile idiopathic arthritis by power color and spectral Doppler ultrasonography

Abstract

Objective: Ultrasonography in patients with juvenile idiopathic arthritis (JIA) could potentially be useful for evaluation of enthesitis. The aim of this study was to evaluate enthesitis in patients with JIA quantitatively by power color and spectral Doppler ultrasonography by determining color fraction (CF) and resistive index (RI).

Methods: A cross-sectional single-center study was performed in 15 (61 entheseal sites) patients with JIA with clinical enthesitis. A total of 9 age and sex matched healthy controls (53 entheseal sites) were also examined and compared. Entheseal sites (quadriceps tendon, patellar tendon, tendo-Achilles, medial and lateral epicondyles of humerus) were examined on USG B mode for tendon thickening, hypo- and hyper-echogenicity, enthesophytes, and cortical erosions/irregularities by power Doppler ultrasound for the presence of Doppler signal and by power color Doppler and spectral Doppler ultrasonography to derive CF and RI respectively.

Results: The mean thickness of entheseal site in patients and controls were 3.55±0.82 mm and 2.8±0.37 mm, respectively (p<0.001). The power Doppler signal was present in 93.4% of patients (p<0.001). The pooled data of all entheseal sites revealed a significantly higher CF in patients (0.08±0.03) than in controls (0.006±0.008) (p<0.001). The mean RI in patients (0.61±0.09) was significantly lower than that in controls (0.92±0.12) (p<0.001). The cut-off of RI (0.7) and CF (0.029) determined by receiver operating curve analysis revealed a diagnostic accuracy of 94.7% and 96.5%, respectively.

Conclusion: Evaluation of enthesitis by determining CF and RI via power color Doppler and spectral Doppler is possible in JIA patients.

Figure 1. a, b

Receiver operating characteristic (ROC) curve for all the enthesis pooled together to obtain a perfect separation between 2 groups (normal vs diseased). Resistive Index - area under the ROC curve (AUC) 0.963 (95% CI: 0.926–1.00) (a). Color fraction - area under the ROC curve (AUC) 0.949 (95% CI: 0.900–0.993) (b).