A CT scan offers complete viewing of the retroperitonium, as opposed to an ultrasound exam where digestive stacking creates a barrier for ultrasound. Thus, a CT scan is the preferred investigation method for detecting adenopathies, evaluating adrenal glands and finding pathologies of the abdominal aorta, aneurysms and stenoses, and evaluating the origin of large abdominal blood vessels (coeliac artery, mesenteric arteries, renal arteries). MRI is the method of choice for diagnosing retroperitoneal fibrosis, due to its characteristic signal.

It should be noted that evaluation of the kidneys and the pancreas were discussed previously.