Patient-Friendly Real-Time Optical Tomographic Imaging System (LOTIS) for Lupus Arthritis

Systemic lupus erythematosus (SLE) frequently presents joint pain and stiffness, yet clinicians lack an objective, rapid method to quantify joint inflammation at the point of care. We introduce the Lupus Optical Tomography Imaging System (LOTIS), a wearable near-infrared (NIR) device that performs real-time three-dimensional tomographic imaging of hemodynamic changes in finger joints. LOTIS was developed to address key limitations of our earlier Flexible Optical Imaging System (FOIS), including mechanical fragility, high noise levels, single-joint acquisition, and slow reconstruction times. The new system integrates modular, mechanically robust optical patches with on-sensor digitization and a computationally efficient, non-iterative multispectral reconstruction algorithm to produce frame-by-frame maps of hemoglobin concentration. In a preliminary study using a standardized venous-occlusion protocol, LOTIS differentiated SLE-affected joints from those of healthy controls. Diseased joints exhibited blunted and spatially diffuse hemodynamic responses, whereas healthy joints showed localized and robust changes. These results demonstrate that LOTIS provides an operator-independent, patient-friendly method for quantifying joint-specific hemodynamic changes in real time, offering strong potential as a clinical tool for objective assessment and longitudinal monitoring of lupus arthritis.