We observed the passive diffusion of water out of a scaffold by proton MRI imaging and using D 2 O as contrast agent. Analysing the distribution of pixel intensities inside the container used, we observed that both the hydrogel (Fig. ) and the cryogel (Fig. ) showed a particle exchange with the surrounding media following Fick's laws of passive diffusion. First, the proton signal intensity arose only from the scaffold, making a small region of the ROI to have high pixel intensities (i.e. water-soaked scaffold). Hence, signals close to the machine's background noise dominated the image. The first kernel density estimates of Fig. and Fig. show this phenomenon for both scaffolds. The highest probability region is located around the background noise value, with the distribution having a long right tail, representing the few scaffold ROI pixels with high intensity. As time progressed, the passive diffusion observed in both cases distributed uniformly the protonated water molecules across the entire container. Consequently, the kernel density estimates evolved towards Gaussian distributions, this time centred at the mean pixel intensity instead of in the background ones.