Non-Hermitian PT-symmetric and Hermitian Hamiltonians' correspondence: Isospectrality and mass signature

A transformation of the form x to iy; x,y in R, or an equivalent similarity transformation with a metric operator $\eta$ are shown to transform non-Hermitian PT-symmetric Hamiltonians into Hermitian partner Hamiltonians in Hilbert space. Isospectrality and mass signature are discussed.