LED based photoacoustic imaging of human inflammatory arthritis (Conference Presentation)

Presenting highly sensitive functional information in subsurface tissue with spatial resolution comparable to ultrasound imaging, the emerging photoacoustic (PA) imaging may shed new lights to early diagnosis and treatment monitoring of human inflammatory arthritis. This paper will introduce our recent development of LED-based PA imaging and its application to human inflammatory arthritis. Facilitated by the high pulse repetition rate of the LED arrays, extensive averaging of PA signal can be performed, which boosts the signal-to-noise ratio of the LED-based PA imaging system to levels comparable to laser-based PA imaging systems. In the experiments on arthritis patients and normal volunteers, each target finger joint is scanned using the LED-based PA imaging system which is integrated with a B-scan ultrasound (US) facilitating dual imaging modalities simultaneously. 2D PA and US of a sagittal section in the joint can be acquired in a real-time fashion with a frame rate up to 30 Hz; while a series of 2D images acquired along the cross sections of the joint can be reconstructed into a 3D image for analyzing the volumetric biomarkers of joint inflammation. In this initial study on human subjects, we have confirmed the feasibility of LED-based PA imaging in detecting and characterizing arthritic joints by evaluating the hemodynamic changes associated with soft-tissue inflammation. PA imaging findings are compared to the results from Doppler US acquired using a commercial US unit. This study demonstrates that the LED-based PA imaging can be developed into a point-of-care diagnostic tool for rheumatology and radiology clinics.