Blood flow measurement with spectrometer-based Fourier domain optical coherence tomography (FD OCT) is limited by the motion-induced signal fading and the resulting reduction of flow sensitivity. In this study, a combination of the established Doppler OCT and the numerically simulated signal damping due to obliquely moved scatterers is used to estimate the systolic blood flow velocities in the in vivo mouse model at which the standard Doppler OCT does not work any longer.