High-resolution functional photoacoustic monitoring of vascular dynamics in human fingers

Abstract

Functional imaging of microvascular dynamics in extremities delivers intuitive information for early detection, diagnosis, and prognosis of vascular diseases. High-resolution and high-speed photoacoustic microscopy (PAM) visualizes and measures multiparametric information of microvessel networks in vivo such as morphology, flow, oxygen saturation, and metabolic rate. Here, we demonstrate high-resolution photoacoustic monitoring of vascular dynamics in human fingers. We photoacoustically monitored the position displacement of blood vessels associated with arterial pulsation in human fingers. Then, during and after arterial occlusion, we photoacoustically quantified oxygen consumption and blood perfusion in the fingertips. The results demonstrate that high-resolution functional PAM could be a vital tool in peripheral vascular examination for measuring heart rate, oxygen consumption, and/or blood perfusion.

Monitoring peripheral hemodynamic response to changes in blood pressure via photoacoustic imaging

“…Hence, this work suggests that PA imaging can be used to monitor peripheral tissue perfusion, a risk factor for wound formation and impaired healing [53] , [54] . Others have also shown the use of PA imaging to visualize tissue perfusion but most studies use high-powered lasers which are expensive, bulky, and pose an exposure risk above the maximum permissible exposure limit [28] , [55] , [56] .…”

“…In pre-clinical settings, PA is used to measure disease biomarkers [20] , oxidative stress [21] , [22] , blood oxygen saturation [23] , and image chronic wounds [24] , [25] . Clinically PA is used for diagnosing and monitoring breast cancer progression [26] , [27] , vascular dynamics in human fingers [28] , inflammatory bowel disease [29] , and many more diseased states [30] , [31] , [32] , [33] . Recently, we demonstrated the ability of PA imaging to monitor angiogenesis and predict wound healing [34] .…”

High-Speed Optical Resolution Photoacoustic Microscopy With a MEMS Scanner: Novel and Simple Distortion Correction Method

“…Although a few studies previously visualized the structure by employing conventional mechanical scanning OR-PAM [51], its slow imaging speed made it di cult for biological interpretation. On the other hand, MEMS-OR-PAM provides fast imaging speed, but many studies were challenging to separately visualize the circulatory structure of human nger capillaries while they could clearly visualize the capillaries of nude mice [25,40,52]. It is because the human skin has strong optical scatterers such as melanin, which makes the lateral resolution degrade to blur the circulatory structure slightly, and thus, the additional image distortion leads to di culty in visualizing such blurred structures separately.…”

“…On the other hand, the latest generation of fast OR-PAM employed a waterproof MEMS scanning mirror [31,32,33,34,35,36,37,38,39,40]. In the fast PAM system, the coaxially and confocally adjusted laser irradiation beam and the ultrasound reception beam were scanned together by the MEMS mirror placed into the water.…”

Monitoring peripheral hemodynamic response to changes in blood pressure via photoacoustic imaging

“…[19] In pre-clinical settings, PA is used to measure disease biomarkers, [20] oxidative stress, [21,22] blood oxygen saturation, [23] and image chronic wounds. [24,25] Clinically PA is used for diagnosing and monitoring breast cancer progression, [26,27] vascular dynamics in human fingers, [28] inflammatory bowel disease, [29] and many more diseased states. [30][31][32][33] Recently, we demonstrated the ability of PA imaging to monitor angiogenesis and predict wound healing.…”