Assessing disease activity in inflammatory arthritis using optical spectral transmission : a systematic review compared to joint ultrasound, MRI, and clinical activity markers

Abstract

Background Early and accurate detection of inflammatory activity is essential in inflammatory arthropathies, as timely treatment can prevent irreversible joint damage. Optical spectral transmission (OST), implemented in the HandScan device, is a novel, non-invasive imaging method that uses red and near-infrared light to detect perfusion changes associated with angiogenesis and hypervascularity in inflamed joints. This review summarizes current evidence on OST, assessing its diagnostic performance and clinical utility relative to musculoskeletal ultrasound, magnetic resonance imaging, and conventional clinical activity indices.

Methods This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant studies were identified through systematic searches of the Web of Science and PubMed databases, with the last search conducted on October 7, 2025, according to predefined inclusion criteria. Publications from 2012 to 2025 were considered eligible. Studies enrolling patients with rheumatic diseases were included, and data were extracted on study population characteristics, methodologies, and main findings.

Results Out of 77 studies screened, 22 met the inclusion criteria. Cross-sectional studies showed significant correlations between OST and ultrasound findings, with areas under the curve (AUC) reaching as high as 0.85. This correlation was particularly strong in the metacarpophalangeal and proximal interphalangeal joints. Additionally, OST correlated with MRI-detected synovitis and tenosynovitis but not with bone marrow edema. Moderate associations were observed between OST and clinical indicators such as DAS28, swollen joint counts, and C-reactive protein levels. Longitudinal analyses revealed significant associations between changes in OST values and changes in clinical activity indices, specifically ΔDAS28, and ΔSJC. However, it was found that absolute OST scores alone were inadequate for distinguishing between different levels of disease activity. Factors such as sex, body mass index, and structural joint damage were identified as confounding variables that influenced the measurements.

Conclusion OST is a promising, rapid, and operator-independent technique for quantifying joint inflammation in rheumatoid arthritis. Although further evaluation of its stand-alone diagnostic accuracy is needed, its integration with clinical assessment and imaging may enhance the objectivity and efficiency of disease monitoring. Standardized measurement protocols and patient-adjusted thresholds will be essential for broader clinical implementation.