CA2963450A1 — Quantification of absolute blood flow in tissue using fluorescence-mediated photoplethysmography

USPTO Abstract

25 ABSTRACT A method, an apparatus, and a kit including the apparatus and a fluorescence agent are provided for measuring a time-varying change in an amount of blood in a tissue volume, and include exciting a fluorescence agent in the blood, acquiring a time-varying light in-5 tensity signal during a pulsatile flow of the blood through the tissue volume, the pulsatile flow having a systolic and a diastolic phase resembling a conventional photoplethysmo- gram, and processing the acquired signal by applying a modified Beer-Lambert law to ob- tain a measurement of the time-varying change in the amount of blood in the tissue vol- ume. The instantaneous molar concentration of the fluorescence agent is determined by 10 utilizing a concentration-mediated change in a fluorescence emission spectrum of the fluo- rescence agent. There is further provided a fluorescence agent for use in the method.