  The relation of the pole and running heavy quark masses of order
$\mathcal{O}\left(\alpha_s^4\right)$ in perturbative quantum chromodynamics
(pQCD) can be obtained using the Principle of Maximum Conformality (PMC), a
formalism that provides a rigorous method for eliminating renormalization scale
and scheme ambiguities for observables in pQCD. Using PMC, an optimal
renormalization scale for the heavy quark mass ratio is determined, independent
of the renormalization scale and scheme up to order $\alpha_s^4$. Precise
values are then obtained for the PMC pole masses of the heavy quarks
$M_b^{\text{PMC}}=4.86^{+0.03}_{-0.02}$ GeV, $M_t^{\text{PMC}}=172.3\pm 0.6$
GeV, and the running mass $\overline{m}_t^{\text{PMC}}=162.6\pm 0.7$ GeV at the
PMC scale.
