Spectral analysis of laser-Doppler perfusion signal measured during thermal test

Abstract

The method of spectral analysis of laser-Doppler perfusion signal measured during thermal test is proposed. During three 20 min phases with 40, 5, and 40°C of thermal test laser-Doppler perfusion signal was recorded. For each signal phase frequency spectra were calculated using the FFT method. Quantitative parameter Spectral Factor for results evaluation was proposed. In total 94 patients were measured: 69 with Raynaud’s phenomenon and 25 normal subjects. Additionaly in 18 Raynaud’s patients the influence of Nifedipine was studied. Results suggest that proposed parameter is able to differentiate between Raynaud’s patients and normal subjects and that is useful for evaluation of Nifedipine effectivenes. However, further studies are needed to improve the method to differentiate between primary and secondary Raynaud’s patients.