Validation of photoacoustic/ultrasound dual imaging in evaluating blood oxygen saturation

Abstract

Photoacoustic imaging (PAI) was performed to evaluate oxygen saturation (sO2) of blood-mimicking phantoms, femoral arteries in beagles, and radial arteries in humans at various sO2 plateaus. The accuracy (root mean square error, RMSE) of PAI sO2 compared with reference sO2 was calculated. In blood-mimicking phantoms, PAI achieved an accuracy of 1.49% and a mean absolute error (MAE) of 1.09% within 25 mm depth, and good linearity (R = 0.968; p < 0.001) was obtained between PAI sO2 and reference sO2. In canine femoral arteries, PAI achieved an accuracy of 2.16% and an MAE of 1.58% within 8 mm depth (R = 0.965; p < 0.001). In human radial arteries, PAI achieved an accuracy of 3.97% and an MAE of 3.28% in depth from 4 to 14 mm (R = 0.892; p < 0.001). For PAI sO2 evaluation at different depths in healthy volunteers, the RMSE accuracy of PAI sO2 increased from 2.66% to 24.96% with depth increasing from 4 to 14 mm. Through the multiscale method, we confirmed the feasibility of the hand-held photoacoustic/ultrasound (PA/US) in evaluating sO2. These results demonstrate the potential clinical value of PAI in evaluating blood sO2. Consequently, protocols for verifying the feasibility of medical devices based on PAI may be established.