# Expansion of a transition amplitude

Consider that $$|\Psi \rangle$$ is a scattering state and we have the matrix element $$\langle \Psi | \hat{V} | \Psi \rangle$$, where $$\hat{V}$$ is a perturbation. Is t possible expand it using the $$S$$-matrix? I read in an article that it's possible, but I can't understand how it's done. I suspect that it's related to the Dyson series.