Abstract: Polyvinyl-alcohol cryogel is commonly used for soft tissue phantom manufacture. The gel formation from an aqueous solution of polyvinyl-alcohol takes place during the freezing and thawing cycle. The aim of this work was to assess the degree of gel solidification, hence the material stiness, by means of quantitative ultrasound. We manufactured three phantoms which diered in the number of freezing/thawing cycles. First, tissue phantoms were examined with an elastography technique. Next, we measured the speed of sound and the attenuation coeÿcient. What is more, the inter structure variations in phantoms were assessed with the Nakagami imag-ing which quantifies the scattering properties of the backscattered ultrasound e cho. Obtained results confirmed the connection between the number of freezing/thawing cycles and the solid-ification p rocess. We defined th e boundary layer as a region wh ich has a dierent structure than the sample interior. Next, for each phantom this layer was extracted based on a Nakagami parameter map. We calculated that the thickness of the boundary layer was lower in samples which were subjected to a larger number of freezing/thawing cycles.