  We present simulated images of Supernova 1993J at 8.4 GHz using Very Long
Baseline Interferometry (VLBI) techniques. A spherically symmetric source model
is convolved with realistic uv-plane distributions, together with standard
imaging procedures, to assess the extent of instrumental effects on the
recovered brightness distribution. In order to facilitate direct comparisons
between the simulations and published VLBI images of SN1993J, the observed
uv-coverage is determined from actual VLBI observations made in the years
following its discovery.
  The underlying source model only exhibits radial variation in its density
profile, with no azimuthal dependence and, even though this model is
morphologically simple, the simulated VLBI observations qualitatively reproduce
many of the azimuthal features of the reported VLBI observations, such as
appearance and evolution of complex azimuthal structure and apparent rotation
of the shell. We demonstrate that such features are inexorably coupled to the
uv-plane sampling.
  The brightness contrast between the peaks and the surrounding shell material
are not as prominent in the simulations (which of course assume no antenna- or
baseline-based amplitude or phase errors, meaning no self-calibration
procedures will have incorporated any such features in models). It is
conclusive that incomplete uv-plane sampling has a drastic effect on the final
images for observations of this nature. Difference imaging reveals residual
emission up to the 8 sigma level. Extreme care should be taken when using
interferometric observations to directly infer the structure of objects such as
supernovae.
