In order to investigate the relationship between nanovoids and two-dimensional scattering patterns (2DSPs) in elongated polymer nanocomposites (PNCs) filled with spherical nanoparticles (NPs), coarse-grained molecular dynamics simulations were performed with polydisperse NPs for Poisson's ratios of nu = 0.46 < 0.5. The polydispersity of NP diameter impacts on creation and early growth of nanovoids. Study of the growth of nanovoids under the attractive NP-polymer interactions showed that large NPs have a role of starting points of the growth. The 2DSP I(q(x),q(yz)) is also calculated as the circular average of scattering intensity I(q), which is obtained by three-dimensional Fourier transformation of the density field weighted by contrasts of the NPs and polymers. It was confirmed that polydispersity of NPs causes disappearance of a ring pattern that was seen for uniform NPs. For the case with attractive NP-polymer interactions, the magnitudes of the central peaks of the 2DSPs was confirmed to become larger for larger elongation ratios. On the other hand, for the case with repulsive NP-polymer interactions, the central peak of the 2DSPs is much weaker than that for the case with attractive NP-polymer interaction, because of the occurrence of interfacial fractures and fine dispersal of nanovoids at the interface between NPs and polymers. In addition, creation and annihilation of a nanovoid during stretching process were observed for the cases with repulsive NP-polymer interactions. For the case with attractive NP-polymer interactions, a kink behavior on a plot of scattering invariant versus the elongation ratio was observed. From this behavior, it was confirmed that the detection of nanovoids through 2DSPs is effective for attractive NP-polymer interaction.