LED based photoacoustic imaging with enhanced sensitivity for human inflammatory arthritis (Conference Presentation)

Our previous research has demonstrated that photoacoustic (PA) imaging is capable of evaluating the pathological condition in human peripheral joints affected by inflammatory arthritis. In this work, we tested the performance of a PA imaging system based on the LED light source and its performance for arthritis imaging. The LED-based PA imaging system not only has less cost but also has smaller footprint and, hence, is more portable and convenient for use in rheumatology clinic. 2D B-scan PA and US images of each metacarpophalangeal (MCP) joint were acquired along the sagittal sections. Along the same sections, US Doppler images were also acquired. Images from 12 joints with clinically active arthritis (i.e., positive on Doppler US), 5 joints with subclinically active arthritis (i.e., negative on Doppler US), and 12 joints of normal volunteers were compared. The blood volume in each joint reflecting hyperemia was quantified by counting the density of the color pixels in each pseudo-color PA image. T-tests were conducted to evaluate whether PA imaging can differentiate the three groups. The results from this study suggest that LED-based PA imaging is capable of detecting hyperemia as an important biomarker of joint inflammation. In addition, PA imaging could differentiate the subclinically active arthritis group and the normal group while Doppler US could not, suggesting that PA imaging has higher sensitivity to mildly hyperemia when compared to Doppler US. The imaging technique presented may contribute to rheumatology clinic by providing a new tool for early diagnosis and treatment evaluation of joint inflammation.