1. An imaging method for identifying abnormal tissue in a lung, comprising: recording slice images of the lung by means of X-ray radiation to produce a slice image of the lung, where the slice image of the lung includes at least one elongate blood vessel and at least one abnormal tissue; determining diameters of the at least one blood vessel and of the at least one abnormal tissue in the slice images by calculating a starting point corresponding to a first end of the at least one blood vessel, commencing from the starting point a wave front of constant speed, and measuring distances at the wave front between opposing walls of the blood vessel and the at least one abnormal tissue, wherein the measured distances provide direct approximations of the diameters, wherein the wave front propagates from the first end of the at least one blood vessel along a longitudinal axis of the at least one blood vessel to a second end of the at least one blood vessel, wherein the wave front is halted at boundaries of the at least one blood vessel; evaluating the diameters of the at least one blood vessel and of the at least one abnormal tissue at the different locations; differentiating the at least one blood vessel and the at least one abnormal tissue based on the evaluated diameters; segmenting the at least one abnormal tissue; and displaying the segmented abnormal tissue on an output device.