Abstract
BackgroundValid detection of arthritis is essential in differential diagnosis of joint pain. Indocyanin green (ICG)-enhanced fluorescence optical imaging (FOI) is a new imaging method that visualizes inflammation in wrist and finger joints. Objectives of this study were to compare FOI with ultrasonography (US, by gray-scale (GS) and power Doppler (PD)) and clinical examination (CE) and to estimate the predictive power of FOI for discrimination between inflammatory and non-inflammatory juvenile joint diseases.MethodsFOI and GSUS/PDUS were performed in both hands of 76 patients with joint pain (53 with juvenile idiopathic arthritis (JIA), 23 with non-inflammatory joint diseases). Inflammation was graded by a semiquantitative score (grades 0–3) for each imaging method. Joints were defined clinically active if swollen or tender with limited range of motion. Sensitivity and specificity of FOI in three phases dependent on ICG enhancement (P1–P3) were analyzed with CE and GSUS/PDUS as reference.ResultsFor JIA patients, FOI had an overall sensitivity of 67.3%/72.0% and a specificity of 65.0%/58.8% with GSUS/PDUS as reference; specificity was highest in P3 (GSUS 94.3%/PDUS 91.7%). FOI was more sensitive for detecting clinically active joints than GSUS/PDUS (75.2% vs 57.3%/32.5%). In patients with non-inflammatory joint diseases both FOI and US showed positive (i.e., pathological) findings (25% and 14% of joints). The predictive value for discrimination between inflammatory and non-inflammatory joint diseases was 0.79 for FOI and 0.80/0.85 for GSUS/PDUS.ConclusionsDependent on the phase evaluated, FOI had moderate to good agreement with CE and US. Both imaging methods revealed limitations and should be interpreted cautiously. FOI may provide an additional diagnostic method in pediatric rheumatology.Trial registrationDeutsches Register Klinischer Studien DRKS00012572. Registered 31 July 2017.
Highlights
Valid detection of arthritis is essential in differential diagnosis of joint pain
We found no relevant differences in the distribution of fluorescence optical imaging activity score (FOIAS) scores between patients aged < 13 years and patients aged ≥ 13 years
The predictive value for discrimination between active inflammatory and non-inflammatory conditions was calculated. We found it to be comparably high for both GSUS/PDUS and fluorescence optical imaging (FOI) (0.80/0.85 and 0.79) with slight advantages for US, showing that they are valid methods for differential diagnosis in children and adolescents with unclear joint pain
Summary
Valid detection of arthritis is essential in differential diagnosis of joint pain. Indocyanin green (ICG)-enhanced fluorescence optical imaging (FOI) is a new imaging method that visualizes inflammation in wrist and finger joints. Objectives of this study were to compare FOI with ultrasonography (US, by gray-scale (GS) and power Doppler (PD)) and clinical examination (CE) and to estimate the predictive power of FOI for discrimination between inflammatory and non-inflammatory juvenile joint diseases. Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory rheumatic disease in childhood and requires early and adequate antiinflammatory treatment [4, 5] as it may lead to permanent joint damage and functional disability [6,7,8]. Ultrasonography (US) in gray-scale (GS) and in power Doppler mode (PD) are established imaging tools for both the detection of synovitis and estimation of current arthritis activity; both techniques have been shown to be more sensitive than CE [11,12,13]. Because of further disadvantages such as high costs, long duration of examination, and the possible need for sedation in younger children, it is not routinely performed in the pediatric rheumatology outpatient clinic
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