System and method for performing laser doppler flowmetry

A system for performing a laser Doppler flowmetry measurement of a blood perfused tissue, the system comprising:

• a light source configured to emit coherent light to the blood perfused tissue;
• a photodetector configured to receive a portion of the coherent light scattered by the blood perfused tissue and generate a photodetector output signal in response to receiving said portion;
• and
• one or more processors configured to determine a selected frequency range (Fselected) for computing a laser Doppler flowmetry signal (LDF signal), wherein the determining the selected frequency range (Fselected) includes
• computing a spectrum (Si(f)) of the photodetector output signal for a series of time intervals (ti), thereby obtaining a series of spectra,
• computing, for a number of different frequencies (f), a measure of an amount of physiological information (Qf) in the spectra (Si(f)), and
• determining the selected frequency range (Fselected) as a range of frequencies (f) for which the measure of the amount of physiological information (Qf) fulfills a predetermined criterion,
• wherein the one or more processors are further configured to compute the LDF signal using the selected frequency range, and to output the LDF signal,
• wherein the measure of the amount of physiological information (Qf) comprises a dispersion d(f) of the spectra, as a function of frequency (f), and
• wherein the predetermined criterion includes a threshold criterion for the dispersion d(f), and the determining the selected frequency range (Fselected) includes
• comparing the dispersion d(f) to a threshold λ,
• determining a minimum frequency (fmin) of the selected frequency range (Fselected) as a first frequency where the threshold λ is crossed for a first time while the dispersion d(f) has a positive slope, such that the dispersion d(f) has a value that increases with increasing frequency across the first frequency while maintaining the positive slope across the first frequency, and
• determining a maximum frequency (fmax) of the selected frequency range (Fselected) as a second frequency where the threshold λ is crossed for a first time while the dispersion d(f) has a negative slope, such that the dispersion d(f) has a value that decreases with increasing frequency across the second frequency while maintaining the negative slope across the second frequency.