(CT or CAT scan) Computed tomography is a diagnostic imaging technique, previously also known as computerized axial tomography (CAT), computer-assisted tomography (CAT), computerized tomographic imaging, and reconstructive tomography (RT).
A CT scan is based on the measurement of the amount of energy that a tissue absorbs as a beam of radiation passes through it from a source to a detector. As the patient table moves through the CT scanner, the CT tube rotates within the circular opening and the set of x-ray detectors rotate in synchrony. The narrow, fan-shaped x-ray beam has widths ranging from 1 to 20 mm. The large number of accurate measurements with precisely controlled geometry is transformed by mathematical procedures to image data. Corresponding to CT slices of a certain thickness, a series of two-dimensional cross-sectional images is created.
A CT is acquired in the axial plane, while coronal and sagittal images can be rendered by computer reconstruction. Although a conventional radiography provides higher resolution for bone x-rays, CT can generate much more detailed images of the soft tissues. Contrast agents are often used for enhanced delineation of anatomy and allow additional 3D reconstructions of arteries and veins.
CT scans use a relatively high amount of ionizing radiation compared to conventional x-ray imaging procedures. Due to widespread use of CT imaging in medicine, the exposure to radiation from CT scans is an important issue. To put this into perspective, the FDA considers the risk of absorbed x-rays from CT scans to be very small. Even so, the FDA recommends avoiding unnecessary exposure to radiation during diagnostic imaging procedures, especially for children.
CT is also used in other than medical fields, such as nondestructive testing of materials including rock, bone, ceramic, metal and soft tissue.

See also Contrast Enhanced Computed Tomography.

(CTE) Computed tomography enterography is an imaging procedure to evaluate diseases affecting the mucosa and bowel wall of the small intestine. CTE uses oral contrast agents to improve bowel wall visualization. Several studies established that small bowel distention using negative oral contrast agent increases diagnostic performance of some abdomen CT studies.
The multi-detector row CT (MDCT) improves temporal and spatial resolution and 3D imaging processes offer a full examination of the small bowel with surrounding structures, depicting the small bowel inflammation associated with Crohn's disease by displaying mural hyperenhancement, stratification, and thickening.
CT enterography versus capsule endoscopy provides a non invasive study with comparable sensitivity, high specificity and overall accuracy.

See also Colonoscopy and Virtual Colonoscopy.

Conray® is a contrast agent intended for intravascular administration as a diagnostic radiopaque medium. Conray® is rapidly transported through the circulatory system to the kidneys and is excreted unchanged in the urine by glomerular filtration.
See also Ionic Contrast Agents, Contrast Media Injector, Dual-Head CT Power Injector, CT Power Injector.

See Dye, Contrast Agents.

The contrast enhancement refers to increasing the visibility of low contrast structures due to increased density of vessels and tissue containing contrast agents.