  The NA60 experiment has studied low-mass muon pair production in In-In
collisions at $158 {\rm AGeV}$ with unprecedented precision. With these results
there is hope that the in-medium modifications of the vector meson spectral
function can be constrained more thoroughly than before. We investigate in
particular what can be learned about collisional broadening by a hot and dense
medium and what constrains the experimental results put on in-medium mass shift
scenarios. The data show a clear indication of considerable in-medium
broadening effects but disfavor mass shift scenarios where the $\rho$-meson
mass scales with the square root of the chiral condensate. Scaling scenarios
which predict at finite density a dropping of the $\rho$-meson mass that is
stronger than that of the quark condensate are clearly ruled out since they are
also accompanied by a sharpening of the spectral function.
