Medicine faces many challenges, among which that of the growing number of old and often frail patients needs to be particularly addressed. In our hospital, that serves one of the oldest population on earth (about 10 % of the inhabitants of Genoa are over 80 years old) problems related to diagnosing and treating pathologies in this type of patients are part of our daily practice. Many old patients enter our hospital for gastrointestinal symptoms possibly related to colorectal cancer, often via the emergency room.In these patients (in which it is frequently difficult to obtain a good clinical history), there is the need to make a diagnosis, preferably noninvasively, to plan appropriate treatment.In colorectal cancer, computed tomography (CT) offers different modalities that allow to diagnose and stage correctly the disease. The most commonly used are two that require good bowel preparation:• CT colonography requires distention of the colon with gas (room air or, preferably, carbon dioxide), usually without iodinated contrast media intravenously but often with orally administered iodinated contrast media (and/or barium) before the examination to properly ''tag'' residual feces and liquids in the colon [1,2]. It is possible to add intravenous contrast media to CT colonography before the examination in patients with high pretest likelihood of positive findings (colon cancer or significant extra-colic findings) [3]. Intravenous contrast media can also be added when required during the CT colonography itself after the first (usually supine) acquisition; but this requires the presence the immediate evaluation of the radiologist during the CT examination, which can be difficult in a real clinical setting (because of the high workflow in the CT suite) and since often colorectal cancer is depicted only after extensive review of the CT images. In CT colonography performed after tagging, intravenous contrast media may, in our experience, make more difficult the assessment/depiction of enhancing bowel wall lesions located in segments with superimposable hyperdensity of the adjacent bowel content. In our opinion, CT colonography should be mainly reserved for old outpatients in good condition, in whom significant colon pathology must be ruled out and there is a low pretest likelihood of significant findings. Hospitalized old and frail patients may have problems in completing the full CT colonography preparation and even in undergoing the CT scan itself with the two required positions of the patient (supine and prone).• Water enema CT is performed after distension of the colon with water and, always, with intravenous iodinated contrast media [4]. This technique can be modified to obtain distention of the small bowel with oral administration of a negative contrast medium such as a polyethylene glycol electrolyte solution [5]. Water enema CT is mainly used in our hospital in those old and frail patients with a high pretest likelihood of colon cancer, based on clinical suspicion. The use of iodinated contrast media intravenously al...