1. A method involving angiographic examination of a patient using a computed tomography scanner with at least one recording system mounted on a gantry so as to be rotatable about a z-axis, the method comprising: acquiring projection data from at least one angular position of the gantry for at least two different energies of X-ray radiation; and combining the acquired projection data corresponding to a respective one of the at least one angular position to form a resulting projection image, in which at least one substance, which is selectively displayable, is imaged with a relatively high image contrast compared to the respective individual projection data.