[en] Analysis is performed of differential cross sections of elastic scattering of pions on different nuclei at energies between 130 and 290 MeV. To this end the pion-nucleus microscopic optical potential (OP) was applied. Such an OP was constructed using the Glauber theory and defined by the target nucleus density distribution of bare nucleons and by the elementary πN-amplitude of scattering. The pion-nucleus cross sections are calculated by numerically solving the corresponding relativistic wave equation. The three parameters of the πN scattering amplitude, the total cross section, the ratio of real to imaginary part of the forward πN-amplitude, and the slope parameter, were fit to the data on the respective pion-nucleus cross sections. Thus, comparing the sets of ''free'' parameters to those obtained from pion-nucleus scattering data, the in-medium effect on the πN scattering amplitude is discussed