1. A method for operating a medical imaging apparatus adapted to receive a patient therein, comprising the steps of: in a freely selectively acquired 3D reference image dataset of a patient, electronically designating a reference data slice; using a medical imaging apparatus, acquiring a 3D image dataset of an examination volume of a patient in the medical imaging device; automatically electronically bringing said 3D image dataset into registration with said 3D reference image dataset; and automatically electronically identifying a slice in said 3D image dataset, for which data are to be acquired in said medical imaging apparatus, corresponding to said reference data slice in the 3D reference image dataset that has been brought into registration with said 3D image dataset.