  The collision-induced shift and broadening of selected dipole transition
lines of pionic helium in gaseous helium at low temperatures up to $T=12$ K and
pressure up to a few bar are calculated within variable phase function
approach. We predict blue shift of the resonance frequencies of the
$(n,l)=(16,15) \rightarrow (16,14) $ and $(16,15) \rightarrow (17,14)$
unfavored transitions and red shift for the favored transition $(17,16)
\rightarrow (16,15)$. The result may be helpful in reducing the systematic
error in proposed future experiments for determination of the negatively
charged pion mass from laser spectroscopy of metastable pionic helium atoms.
