Photoacoustic imaging of the spatial distribution of oxygen saturation in an ischemia-reperfusion model in humans.

Photoacoustic imaging (PAI) is a novel hybrid imaging technique that combines the advantages of optical and ultrasound imaging to produce hyperspectral images of the tissue. The feasibility of measuring oxygen saturation (sO2) with PAI has been demonstrated pre-clinically, but has limited use in humans under conditions of ischemia and reperfusion. As an important step towards making PAI clinically available, we present a study in which PAI was used to estimate the spatial distribution of sO2 in vivo during and after occlusion of the finger of eight healthy volunteers. The results were compared with a commercial oxygen saturation monitor based on diffuse reflectance spectroscopy. We here describe the capability of PAI to provide spatially resolved picture of the evolution of sO2 during ischemia following vascular occlusion of a finger, demonstrating the clinical viability of PAI as a non-invasive diagnostic tool for diseases indicated by impaired microvascularization.