Could You please give me a link to a source where I can get (for free) a data set of contrasted CT images of an abdominal aortic aneurism in DICOM (or which?) format manually segmented by a specialist? Even a normal abdominal aorta will fit.
You may need to expand your search to abdominal CTs that have the aorta segmented out. My quick search didn't reveal any aortic aneurysm data sets. For example, this abstract discusses a few data sets that may be useful to you. https://zenodo.org/record/1169361#.YXVkiBwpA6Q