Described herein is an optical coherence tomograph (OCT) angiography technique based on the decorrelation of OCT signal amplitude to provide flow information. The full OCT spectrum can be split into several narrower spectral bands, resulting in the OCT resolution cell in each band being isotropic and less susceptible to axial motion nose. Inter-B-scan decorrelation can be determined using the individual spectral bands separately and then averaged. Recombining the decorrelation images from the spectral bands yields angiograms that use the full information in the entire OCT spectral range. Such images provide significant improvement of signal-to-noise ratio (SNR) for both flow detection and connectivity of microvascular networks compared to other techniques. Further, creation of isotropic resolution cells can be useful for quantifying flow having equal sensitivity to axial and transverse flow.