Imaging of human peripheral blood vessels during cuff occlusion with a compact LED-based photoacoustic and ultrasound system

摘要

Non-invasive imaging plays an important role in diagnosing and monitoring peripheral artery disease (PAD). Dopplerultrasound imaging can be used for measuring blood flow in this context. However, this technique frequently provideslow contrast for flow in small vessels. Photoacoustic imaging can allow for the visualization of blood in small vessels,with direct contrast from optical absorption of hemoglobin. In this work, we investigate the potential applications of acompact LED-based photoacoustic (850 nm) and ultrasound imaging system for visualizing human peripheral bloodvessels during cuff occlusion. Each measurement comprised three stages. First, a baseline measurement of a digitalartery of a human finger from a volunteer without a diagnosis of PAD was performed for several seconds. Second,arterial blood flow was stopped using an occlusion cuff, with a rapid increase of pressure up to 220 mm Hg. Third, theocclusion cuff was released rapidly. Raw photoacoustic and ultrasound image data (frame rate: 70 Hz) were recorded forthe entire duration of the measurement (20 s). The average photoacoustic image amplitude over an image region thatenclosed the digital artery was calculated. With this value, pulsations of image amplitudes from the arteries was clearlyvisualized. The average photoacoustic image amplitude decreased during the increase in cuff pressure and it wasfollowed by a rapid recovery during cuff release. With real-time non-invasive measurements of peripheral blood vesseldynamics in vivo, the compact LED-based system could be valuable for point-of-care imaging to guide treatment ofPAD.