Fig. 1

Sketch of the image processing workflow. The workflow of the NuFD consists of the acquisition of the image series in free breathing (step 1), the image registration using ANTs (step 2) and a manual segmentation (step 3). The lung signal is low- and high-pass filtered to separate the ventilation (V) and perfusion signals (Q) (step 4), respectively. Resampling based on a short-term Fourier transform is performed on both signal components individually in order to transform uniformly sampled signals with varying frequency to non-uniformly sampled signals with constant frequency (step 5). Calculating the NuFFT pixel-wise for both ventilation and perfusion (step 6) and extracting the signal amplitude of the corresponding peak allows to generate V- and Q-weighted maps of the segmented lung that are then overlayed on the original image (step 7)