Calibration and validation scheme for in vivo spectroscopic imaging of tissue oxygenation

The determination of the level of oxygenation in optically accessible tissues using multispectral or hyperspectral imaging (HSI) of oxy- and deoxyhemoglobin has special appeal in clinical work due to its noninvasiveness, ease of use, and capability of providing molecular and anatomical information at near video rates during surgery. In this paper we refer to an example of the use of HSI in monitoring oxygenation of kidneys during partial nephrectomy. In a study using porcine models, it was found that artery-only clamping left the kidney better oxygenated, as opposed to simultaneously clamping the artery and the vein. A subsequent study correlates gradations in blood flow by partial clamping during the surgical procedure with postoperative renal function via assessment of creatinine level. We discuss the various contributions to the uncertainty of the oxygen saturation measured by this remote-sensing imaging technique in medical application.