A Functional Study of Human Inflammatory Arthritis Using Photoacoustic Imaging

Abstract

By using our dual-modality system enabling simultaneous real-time ultrasound (US) and photoacoustic (PA) imaging of human peripheral joints, we explored the potential contribution of PA imaging modality to rheumatology clinic. By performing PA imaging at a single laser wavelength, the spatially distributed hemoglobin content reflecting the hyperemia in synovial tissue in metacarpophalangeal (MCP) joints of 16 patients were imaged, and compared to the results from 16 healthy controls. In addition, by performing PA imaging at two laser wavelengths, the spatially distributed hemoglobin oxygenation reflecting the hypoxia in inflammatory joints of 10 patients were imaged, and compared to the results from 10 healthy controls. The statistical analyses of the PA imaging results demonstrated significant differences (p < 0.001) in quantified hemoglobin content and oxygenation between the unequivocally arthritic joints and the normal joints. Increased hyperemia and increased hypoxia, two important physiological biomarkers of synovitis reflecting the increased metabolic demand and the relatively inadequate oxygen delivery in affected synovium, can both be objectively and non-invasively evaluated by PA imaging. The proposed dual-modality system has the potential of providing additional diagnostic information over the traditional US imaging approaches and introducing novel imaging biomarkers for diagnosis and treatment evaluation of inflammatory arthritis.

Reflection artifact identification in photoacoustic imaging using multi-wavelength excitation

“…Therefore, PAI provides optical absorption contrast and has the ability to image deeper than purely optical imaging techniques at ultrasonic resolution. Exploiting these properties, current research is focusing on investigating its clinical applications such as imaging of breast cancer [2,3], rheumatoid arthritis [4,5], and atherosclerosis [6]. Additionally, multispectral PAI strengthens the advantages of this technique for screening and monitoring human diseases, for instance by examining the oxygen saturation of hemoglobin (sO 2 ) in the lesion [3] or characterizing different tissues [6].…”

Light Emitting Diodes based Photoacoustic Imaging and Potential Clinical Applications

“…These relatively smaller joints are usually among the first to be affected by inflammatory arthritis. The early research findings from animal models and human subjects suggest that PA imaging holds promise for rheumatology clinic, and can provide a low-cost and non-invasive tool for early diagnosis and treatment monitoring of inflammatory arthritis 35 – 39 . In this research, we explored the feasibility of detecting soft tissue inflammation in human peripheral joints by using the LED-based PA system, and its capability in differentiating arthritic joints from normal joints by evaluating the enhanced microvascular flow in the synovial tissue.…”

Recent Development of Technology and Application of Photoacoustic Molecular Imaging Toward Clinical Translation

“…Figure 2E shows their quantification study on the finger joints of 7 healthy volunteers and 10 rheumatoid arthritis patients. It appeared that inflamed (8,9). With a photoacoustic-ultrasound dual-imaging system, they could evaluate the increased hemoglobin content, exposing hyperemia, in arthritic joints over normal joints.…”