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

Photoacoustic imaging (PAI) was performed to evaluate oxygen saturation ( s O 2 ) of blood-mimicking phantoms, femoral arteries in beagles, and radial arteries in humans at various s O 2 plateaus. The accuracy (root mean square error, RMSE) of PAI s O 2 compared with reference s O 2 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 s O 2 and reference s O 2 . 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 s O 2 evaluation at different depths in healthy volunteers, the RMSE accuracy of PAI s O 2 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 s O 2 . These results demonstrate the potential clinical value of PAI in evaluating blood s O 2 . Consequently, protocols for verifying the feasibility of medical devices based on PAI may be established.