Abstract
ObjectiveFluorescence optical imaging (FOI) demonstrates enhanced microcirculation in finger joints as a sign of inflammation. We wanted to assess the validity and diagnostic performance of FOI measuring synovitis in persons with hand OA, comparing it with magnetic resonance imaging (MRI)- and ultrasound-detected synovitis.MethodsTwo hundred and twenty-one participants with hand OA underwent FOI and ultrasound (gray-scale synovitis and power Doppler activity) of the bilateral hands and contrast-enhanced MRI examination of the dominant hand. Fifteen joints in each hand were scored on semi-quantitative scales (grade 0–3) for all modalities. Four FOI images were evaluated: one composite image (Prima Vista Mode (PVM)) and three images representing phases of fluorescent dye distribution. Spearman’s correlation coefficients were calculated between sum scores of FOI, MRI, and ultrasound. Sensitivity, specificity, and area under the curve (AUC) were calculated for FOI using MRI or ultrasound as reference.ResultsFOI did not demonstrate enhancement in the thumb base, and the joint was excluded from further analyses. FOI sum scores showed poor to fair correlations with MRI (rho 0.01–0.24) and GS synovitis sum scores (rho 0.12–0.25). None of the FOI images demonstrated both good sensitivity and specificity, and the AUC ranged from 0.50–0.61 and 0.51–0.63 with MRI and GS synovitis as reference, respectively. FOI demonstrated similar diagnostic performance with PD activity and GS synovitis as reference.ConclusionFOI enhancement correlated poorly with synovitis assessed by more established imaging modalities, questioning the value of FOI for the evaluation of synovitis in hand OA.
Highlights
Hand OA is a whole joint disease, affecting the cartilage, subchondral bone, synovium, and tendons [1]; the importance of inflammation in the hand OA pathogenesis remains debated
The TB region is assessed as a whole for Fluorescence optical imaging (FOI), as the 1st carpometacarpal joint (CMC-1) and STT joint cannot be distinguished scores, we found a significant trend for higher proportion of joints with FOI enhancement in joints with severe Kellgren Lawrence (KL) and Verbruggen Veys (VV) grades (Online supplementary figure 1)
Results from subgroup analysis Correlation analyses were repeated for participants with erosive hand OA without consistent improvements in the correlations between FOI, magnetic resonance imaging (MRI), and GS synovitis
Summary
Hand OA is a whole joint disease, affecting the cartilage, subchondral bone, synovium, and tendons [1]; the importance of inflammation in the hand OA pathogenesis remains debated. Ultrasound and magnetic resonance imaging (MRI) examinations have demonstrated a significant inflammatory burden in these patients, and synovitis is associated with pain [2] and radiographic progression on joint level [3, 4]. Whereas previous studies were not able to show clear clinically relevant effects [5], Kroon et al recently showed significant effects of prednisolone on pain in persons with inflammatory hand OA, further supporting the role of inflammation in the pathogenesis of pain [6]. Valid and cost-efficient evaluation of inflammation will be important in future hand OA trials using synovitis as an inclusion criteria and/or outcome measure. Ultrasound and MRI are established modalities for assessing synovitis; they are limited by operator dependency and availability, contraindications, and higher cost, respectively. The method is without radiation, a scan of both hands takes only 6 min, and the device can be operated by trained health professionals
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