1. A method for segmentation of an object from a background in three-dimensional (3D) image data, comprising: initiating a plurality of seeds in the object in a two-dimensional (2D) representation of the 3D image, of which at least one seed defines the object; determining a distribution of intensity levels of pixels in the 2D representation of the 3D image relative to an intensity level of a seed; segmenting the object from the background in a 2D representation of the 3D image based on the distribution of intensity levels into a first 2D segmentation contour; establishing a 2D segmentation contour of the object in at least two additional 2D representations of the image, each 2D representation containing a seed in the object; and creating a 3D segmentation contour of the object by applying a random walker segmentation method to all pixels in the 3D image, using pixels inside the 2D segmentation contours as object pixels and pixels outside the 2D segmentation contours as background pixels.