Fluorescence optical imaging with indocyanine green distinguished psoriatic arthritis from erosive hand osteoarthritis in a study of 101 patients.

Patients with erosive hand osteoarthritis (EHOA) had stronger joint enhancement in finger joints, while psoriatic arthritis (PsA) was more often associated with a unique imaging pattern.

The study included 54 patients with PsA and 47 with EHOA. The mean age was 42 years in the PsA group and 64 years in the EHOA group. Women made up 94% of the EHOA group and 69% of the PsA group. At the time of examination, nearly half of PsA patients were receiving disease-modifying antirheumatic drugs.

All patients underwent Fluorescence optical imaging (FOI) of 16 joints in each hand. Investigators applied a standardized scoring system across multiple imaging phases and assessed four morphologic patterns. In total, more than 3,200 joints were evaluated. Patients with EHOA had stronger enhancement in proximal and distal interphalangeal joints compared with those with PsA. The mean score for proximal interphalangeal joints was 39 in EHOA and 20 in PsA. For distal interphalangeal joints, the mean was 16 in EHOA and 8 in PsA.

The Werner sign, a triangular enhancement extending from the nail bed into the distal interphalangeal joint, was observed in 56% of PsA cases and 21% of EHOA cases. This was the only morphologic feature that reliably differentiated the two conditions. Other patterns did not differ between groups. FOI-based reader diagnosis matched clinical diagnosis in 78% of cases. Inter-reader reliability was substantial for joint signal enhancement in proximal and distal interphalangeal joints, while recognition of morphologic patterns had lower agreement.

The study's retrospective design limited control of confounding factors such as treatment status and disease duration. The EHOA group was older and had greater disease activity, which may have contributed to stronger imaging signals. Nearly half of the PsA group was receiving systemic therapy, which could have also reduced FOI enhancement. Missing information on psoriatic nail involvement further limited interpretation of certain imaging patterns.

FOI with standardized scoring demonstrated measurable differences between PsA and EHOA. Stronger enhancement in proximal and distal interphalangeal joints was associated with EHOA, while the Werner sign was more frequent in PsA. Although some diagnostic overlap remained, the study showed that FOI can be applied reliably for joint signal evaluation and may support differential diagnosis between these conditions.

Full disclosures can be found in the published study.

Source: Frontiers in Medicine