Method for non-invasive monitoring of fluorescent tracer agent with diffuse reflection corrections

A method of assessment of renal function by monitoring a time-varying fluorescence signal emitted from a fluorescent agent from within a diffuse reflecting medium with time-varying optical properties, the method comprising:

• using a renal monitoring system comprising at least one light source, at least one light detector, at least one optical filter, and at least one controller to provide a measurement data set comprising a plurality of measurement entries, each measurement data entry comprising at least two measurements obtained at one data acquisition time from a patient before and after administration of the fluorescent agent, the at least two measurements selected from:
• a DRex signal detected at a second region adjacent to the diffuse reflecting medium by an unfiltered light detector during illumination of the diffuse reflecting medium by excitatory-wavelength light from a first region adjacent to the diffuse reflecting medium;
• an Flr signal detected at a third region adjacent to the diffuse reflecting medium by a filtered light detector during illumination of the diffuse reflecting medium by excitatory-wavelength light from the first region;
• and
• a DRem signal detected at the second region by the unfiltered light detector during illumination of the diffuse reflecting medium by emission-wavelength light from the first region;
• identifying a post-agent administration portion of the measurement data set;
• and
• transforming each Flr signal of each measurement data entry within the post-agent administration portion of the measurement data set to an IF signal representing a detected fluorescence intensity emitted solely by the fluorescent agent from within the diffuse reflecting medium, wherein transforming comprises combining the at least two measurements according to a transformation relation comprising a mathematical equation converting Flr to IF,
• wherein the at least two measurements are selected from a DRem,filtered signal detected at the third region by the filtered light detector during illumination of the diffuse reflecting medium by emission-wavelength light from the first region, and
• wherein rate of the decrease in intensity of the detected fluorescence is representative of clearance of the fluorescent agent by the kidneys.