Patent ID: 7529576

Claim:
A device for measuring blood flow in an organ using an injected indicator comprising: a radiation source for emitting near infrared radiation into tissue of the organ at a first location; a sensor for detecting a proportion of the emitted near infrared radiation that exits from the organ at a second location; and an evaluation unit that detects the proportion of the emitted near infrared radiation that exits from tissue of the organ as a single input signal, said evaluation unit being programmed to perform the following evaluation steps: (a) dividing up said single input signal into a pulsatile component and a non-pulsatile component; (b) determining an injected indicator concentration with reference to the organ tissue from said non-pulsatile component of said single input signal; (c) iteratively determining, from said non-pulsatile component, an inflow function i(t) that characterizes blood flow through the organ by incrementally varying a mean transit time mtt until a stop criterion is reached; (d) determining an injected indicator concentration with reference to blood volume in the organ from said pulsatile component of said single input signal and the iteratively determined inflow function i(t); (e) calculating a blood volume in the organ as a quotient of the injected indicator concentration with reference to the organ tissue and the injected indicator concentration with reference to the blood volume in the organ; and (f) calculating a blood flow in the organ as a quotient of the blood volume in the organ and the mean transit time mtt when the stop criterion has been reached.