Laser speckle contrast analysis in rheumatoid arthritis: a pilot study

Early diagnosis and treatment is paramount in rheumatoid arthritis (RA). Nowadays, there is a need for quick and non-invasive imaging modalities, for which laser speckle contrast analysis (LASCA), a technique that assesses the peripheral blood perfusion (PBP) on a microvascular level, seems to be a promising candidate. The goal of this pilot study was to examine whether the expected increased PBP in active synovitis in RA patients can be detected by LASCA. Thirty RA patients with active synovitis in a finger joint and 44 healthy controls (HC) underwent LASCA examination. The PBP measured over the finger joints was expressed in perfusion units (PU). For the final analysis, all 30 RA patients were matched by age and gender to 30 HC. For the primary analysis the mean difference in PU between joints with active synovitis compared to matched HC, adjusted for type of joint (MCP/PIP), finger, surface and side of hand and for the matching variables (age and gender), was calculated using a multilevel linear model. For the secondary analysis this mean difference in PU was calculated on a monoarticular level. The primary analysis showed an estimated mean difference of 8.79 PU (95%CI -7.79-25.37 PU; p=0.299). For the secondary analysis on a monoarticular level, none of the estimated mean differences differed significantly. In this pilot study examining the use of LASCA in RA, no significant difference in estimated mean PBP between joints with active synovitis in RA and joints without active synovitis in HC could be detected.