OP0354 Radiographic erosions are associated with fluorescence optical imagingenhancement in hand osteoarthritis
Authors: Ø. Maugesten, S. Ohrndorf, S.V. Hestetun, T.K. Kvien, T. Uhlig, I.K. Haugen
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Erosive hand osteoarthritis (OA) is a phenotype characterised by more inflammation and erosions of the subchondral bone. Fluorescence optical imaging (FOI) is a novel imaging technique demonstrating altered microcirculation in wrist and finger joints as a sign of inflammation. No previous hand OA study has explored the validity of FOI against radiography. <h3>Objectives</h3> The aim of the current study was to explore the association between radiographic findings and FOI enhancement in the distal (DIP) and proximal interphalangeal (PIP) joints. <h3>Methods</h3> The NOR-HAND study is an observational hand OA study, in which 251 patients (88% female, median age 61 (interquartile range 56–66) years, 35% erosive hand OA) underwent FOI and x-rays of both hands. The FOI-scan was performed after the administration of an intravenous fluorescence dye (indocyanine green, ICG) and 360 images (1/second) were produced in 6 min. Based on the inflow and washing out of the dye the pictures were divided into 3 phases. Finally, the prima vista mode (PVM) represented a composite picture of the first 240 images of the examination. For each phase, fluorescence enhancement in the joints was graded from 0–3 based on signal intensity. Radiographic severity of the joints was evaluated with the Verbruggen Veys (VV) anatomical phase scoring system, which is based on the assumption that OA in finger joints will progress through different phases. To study whether more advanced radiographic phases were associated with FOI enhancement in the same joint, we applied logistic regression analyses with generalised estimating equations adjusting for age, sex, BMI and absence/presence of erosive hand OA, defined at patient level as having at least one DIP and PIP joint(s) in the erosive or remodelled phase. <h3>Results</h3> FOI demonstrated no and uncommon enhancement of the metacarpophalangeal and thumb base joints, respectively, thus we analysed DIP and PIP joints only. FOI enhancement was most commonly seen in phase 2 and PVM, also in the non-affected joints (table 1). The frequency of enhancement was lower for phase 3 and in particular for phase 1. Joints in the erosive phase had statistically significantly higher odds of FOI enhancement in phase 1, 2 and PVM as compared to the non-affected joints (table 1). Having erosive hand OA in other DIP and PIP joints was also associated with FOI enhancement (p&lt;0.05 in all phases except in phase 1), and our stratified analyses confirmed that FOI enhancement in the non-erosive phases was more common in the erosive vs the non-erosive hand OA patients. <h3>Conclusions</h3> Joints in the erosive phase have more frequent FOI enhancement than non-affected joints. Furthermore, FOI enhancement in non-erosive phases is more common in patients with erosive vs non-erosive hand OA, suggesting that erosive hand OA is a more inflammatory phenotype. FOI enhancement in phase 2, 3 and PVM was common in joints without radiographic pathology, whereas enhancement in phase 1 was uncommon in joints with severe pathology. Thus, there is a need to consider other FOI scoring methods for the assessment of FOI enhancement in hand OA. <h3>Disclosure of Interest</h3> None declared