Photoacoustic-based sO2 estimation through excised bovine prostate tissue with interstitial light delivery.Photoacoustic (PA) imaging is capable of probing blood oxygen saturation (sO2), which has been shown to correlate with tissue hypoxia, a promising cancer biomarker. 
Photoacoustic
Study results for bovine blood samples at distances up to 20 mm from the irradiation source show that local fluence correction improved average sO2 estimation error from 16.8% to 3.2% and maintained an average precision of 2.3% when compared to matched CO-oximeter sO2 measurements. 
CO-oximeter