High-resolution CT (HRCT) of the chest is typically performed without intravenous contrast because it focuses on detailed lung parenchyma and interstitial patterns. Contrast is not routinely required but may be added selectively when assessing vascular structures, mediastinal pathology, suspected malignancy, or when combined with other CT protocols. Your clinician will decide based on the clinical question, kidney function, and allergy history.

A CT abdomen with contrast is ordered to better visualize abdominal organs, blood vessels, and lesions. Contrast highlights tissue differences, improving detection and characterization of tumors, infections, inflammation, abscesses, bowel disease, vascular issues, and trauma. It helps define lesion borders and blood flow. Risks include allergic reaction and kidney effects, so doctors check allergy history and kidney function before giving contrast.

You can usually wear comfortable, loose clothing without metal (zippers, snaps, underwire) for an abdominal CT, but many facilities will ask you to change into a hospital gown if your clothes or jewelry could interfere. Remove belts, piercings and underwire bras; you’ll also need to follow any specific instructions about contrast or IV access given by the radiology team.

An abdominal CT with contrast visualizes the liver, spleen, pancreas, gallbladder and bile ducts, kidneys and adrenal glands, stomach, small and large bowel, and the abdominal aorta with branches. It also shows mesentery, lymph nodes, peritoneal and retroperitoneal spaces, pelvic organs (bladder, uterus, ovaries/prostate) and vascular structures, helping detect tumors, inflammation, infection, bleeding and vascular problems.

HRCT exposes you to ionizing radiation, slightly increasing lifetime cancer risk—risk rises with repeated scans. If iodinated contrast is used, there’s a small chance of allergic reactions and kidney injury, especially with preexisting renal disease. False-positive or incidental findings can prompt extra tests and anxiety. HRCT is usually avoided in pregnancy unless essential.

CT with iodinated contrast is generally safe for most people. Risks include rare allergic reactions and contrast-related kidney injury, especially with pre-existing kidney disease or diabetes. Inform your care team about allergies, medications (e.g., metformin), or pregnancy; your kidney function may be checked and you may be advised to hydrate. Severe complications are uncommon; benefits usually outweigh risks when clinically indicated.