Lattice QCD simulations provide a promising way to disentangle different interpretations of hadronic resonances, which might be of particular relevance to understand the nature of the so-called particles. Recent studies have shown that in addition to the well-established naive quark model picture, the axial-vector meson can also be understood as a dynamically generated state built upon the interaction. In this work, we calculate the energy levels of the system in the channel in finite volume using the chiral unitary approach. We propose to calculate the loop function in the dimensional regularization scheme, which is equivalent to the hybrid approach adopted in previous studies. We also study the inverse problem of extracting the bound state information from synthetic lattice QCD data and comment on the difference between our approach and the Lüscher method.