Optical Spectral Transmission Imaging in Patients with Osteoarthritis: A Comparative Study with Joint Ultrasound and Clinical Markers

This study aimed to evaluate the diagnostic performance of optical spectral transmission (OST) in patients with hand osteoarthritis (OA) and to assess its associations with clinical findings, joint ultrasound (US) markers of active OA, and patient- and disease-related characteristics. In this exploratory pilot study, consecutive patients with OA and healthy controls underwent OST measurements using the HandScan ® device. Clinical examinations and inflammatory markers (C-reactive protein, erythrocyte sedimentation rate) were obtained. A subset of patients underwent standardized joint US [greyscale (GSUS)/power Doppler (PDUS)]. Correlations between OST and clinical, anthropometric and US parameters were examined, and receiver operating characteristics (ROC) assessed discriminative ability. Linear regression was used to evaluate confounding effects. A total of 2910 joints of 97 patients with OA were examined via OST and compared to 3300 joints of 100 control subjects. OST values were significantly higher in patients with OA than in controls (10.39 ± 1.82 vs. 7.51 ± 3.80; p < 0.001), and this difference remained significant after adjustment for potential confounders ( β = 1.698; 95% CI 0.149–3.247; p adj = 0.032). OST showed a weak but significant correlation with PDUS when distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints were analysed together ( ρ = 0.11, p = 0.014). At the DIP joint level, OST correlated weakly but significantly with both GSUS ( ρ = 0.19, p = 0.004) and PDUS ( ρ = 0.22, p = 0.001). Moderate correlations with hand size were observed in patients with OA ( ρ = 0.36, p < 0.001) and controls ( ρ = 0.40, p < 0.001). ROC analysis revealed a moderate discriminative ability [patients vs. controls: area under the curve (AUC) 0.718; 95% CI 0.645–0.792; p < 0.001]. OST correlated with US synovitis markers and demonstrated a moderate/significant capacity to distinguish patients with OA from controls. As a rapid, non-invasive and examiner-independent technique, OST may represent a useful adjunctive tool in the diagnostic assessment of hand OA.