The Mass Distribution in Low Surface Brightness Galaxies
  The distribution of the stellar and gaseous components in low surface brightness galaxies has been determined directly from optical and HI imaging. The distribution of what might be the dominant mass component, the dark matter, which is inferred from rotation curves, is far harder to determine. Although the rotation curves themselves can be determined fairly accurately from HI synthesis observations, and in particular from H$\alpha$ spectroscopy, the uncertainty in the mass modeling leaves room for a wide range of possible dark matter distributions, ranging from maximum stellar disks with shallow dark halos to cuspy dark halos with little mass in stars. 
Rob Swaters