Method for providing image data of a hollow organ, comprising - generating spectrally resolved computed tomography data of an examination area comprising a hollow organ, wherein the hollow organ is an organ of the digestive system comprising a lumen filled with a first contrast agent, said first contrast agent having been applied orally, wherein a second contrast agent is accumulated after the application of the first contrast agent in a blood vessel system, a wall of the hollow organ and a parenchymal organ, the blood vessel system supplying the wall of the hollow organ and the parenchymal organ, the second contrast agent having a different absorption spectrum than the first contrast agent, - calculating first image data indicative of a presence of the first contrast agent and second image data indicative of a presence of the second contrast agent by applying a material separation algorithm onto the spectrally resolved computed tomography data, - providing the image data of the hollow organ comprising the first image data and the second image data, - generating a representation of a border of the contrast agent filling of the lumen based on the first image data, - generating a representation of the wall of the hollow organ based on the representation of the border of the contrast agent filling of the lumen and the second image data, - wherein the lumen of the hollow organ comprises at least one portion (A, S) external to the contrast agent filling of the lumen and adjacent to the wall of the hollow organ, - wherein a representation of the at least one portion (A, S) of the lumen is generated based on the representation of the border of the contrast agent filling of the lumen and the representation of the wall of the hollow organ. - generating spectrally resolved computed tomography data of an examination area comprising a hollow organ, wherein the hollow organ is an organ of the digestive system comprising a lumen filled with a first contrast agent, said first contrast agent having been applied orally, wherein a second contrast agent is accumulated after the application of the first contrast agent in a blood vessel system, a wall of the hollow organ and a parenchymal organ, the blood vessel system supplying the wall of the hollow organ and the parenchymal organ, the second contrast agent having a different absorption spectrum than the first contrast agent, - calculating first image data indicative of a presence of the first contrast agent and second image data indicative of a presence of the second contrast agent by applying a material separation algorithm onto the spectrally resolved computed tomography data, - providing the image data of the hollow organ comprising the first image data and the second image data, - generating a representation of a border of the contrast agent filling of the lumen based on the first image data, - generating a representation of the wall of the hollow organ based on the representation of the border of the contrast agent filling of the lumen and the second image data, - wherein the lumen of the hollow organ comprises at least one portion (A, S) external to the contrast agent filling of the lumen and adjacent to the wall of the hollow organ, - wherein a representation of the at least one portion (A, S) of the lumen is generated based on the representation of the border of the contrast agent filling of the lumen and the representation of the wall of the hollow organ.