Colonography, Computed Tomographic: A non-invasive imaging method that uses computed tomographic data combined with specialized imaging software to examine the colon.Colonic Polyps: Discrete tissue masses that protrude into the lumen of the COLON. These POLYPS are connected to the wall of the colon either by a stalk, pedunculus, or by a broad base.Colonoscopy: Endoscopic examination, therapy or surgery of the luminal surface of the colon.Diatrizoate Meglumine: A versatile contrast medium used for DIAGNOSTIC X-RAY RADIOLOGY.Laxatives: Agents that produce a soft formed stool, and relax and loosen the bowels, typically used over a protracted period, to relieve CONSTIPATION.Enema: A solution or compound that is introduced into the RECTUM with the purpose of cleansing the COLON or for diagnostic procedures.Cathartics: Agents that are used to stimulate evacuation of the bowels.Radiographic Image Interpretation, Computer-Assisted: Computer systems or networks designed to provide radiographic interpretive information.Colorectal Neoplasms: Tumors or cancer of the COLON or the RECTUM or both. Risk factors for colorectal cancer include chronic ULCERATIVE COLITIS; FAMILIAL POLYPOSIS COLI; exposure to ASBESTOS; and irradiation of the CERVIX UTERI.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Insufflation: The act of blowing a powder, vapor, or gas into any body cavity for experimental, diagnostic, or therapeutic purposes.Iothalamate Meglumine: A radiopaque medium used for urography, angiography, venography, and myelography. It is highly viscous and binds to plasma proteins.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Barium Sulfate: A compound used as an x-ray contrast medium that occurs in nature as the mineral barite. It is also used in various manufacturing applications and mixed into heavy concrete to serve as a radiation shield.Radiographic Image Enhancement: Improvement in the quality of an x-ray image by use of an intensifying screen, tube, or filter and by optimum exposure techniques. Digital processing methods are often employed.Contrast Media: Substances used to allow enhanced visualization of tissues.Imaging, Three-Dimensional: The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.Tomography Scanners, X-Ray Computed: X-ray image-detecting devices that make a focused image of body structures lying in a predetermined plane from which more complex images are computed.Mass Screening: Organized periodic procedures performed on large groups of people for the purpose of detecting disease.Colonic Diseases: Pathological processes in the COLON region of the large intestine (INTESTINE, LARGE).Tomography: Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Colon: The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.Radiology: A specialty concerned with the use of x-ray and other forms of radiant energy in the diagnosis and treatment of disease.Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.False Positive Reactions: Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)Tomography, Optical: Projection of near-IR light (INFRARED RAYS), in the 700-1000 nm region, across an object in parallel beams to an array of sensitive photodetectors. This is repeated at various angles and a mathematical reconstruction provides three dimensional MEDICAL IMAGING of tissues. Based on the relative transparency of tissues to this spectra, it has been used to monitor local oxygenation, brain and joints.Pattern Recognition, Automated: In INFORMATION RETRIEVAL, machine-sensing or identification of visible patterns (shapes, forms, and configurations). (Harrod's Librarians' Glossary, 7th ed)Prone Position: The posture of an individual lying face down.Iohexol: An effective non-ionic, water-soluble contrast agent which is used in myelography, arthrography, nephroangiography, arteriography, and other radiographic procedures. Its low systemic toxicity is the combined result of low chemotoxicity and low osmolality.Early Detection of Cancer: Methods to identify and characterize cancer in the early stages of disease and predict tumor behavior.Incidental Findings: Unanticipated information discovered in the course of testing or medical care. Used in discussions of information that may have social or psychological consequences, such as when it is learned that a child's biological father is someone other than the putative father, or that a person tested for one disease or disorder has, or is at risk for, something else.Occult Blood: Chemical, spectroscopic, or microscopic detection of extremely small amounts of blood.Polyps: Discrete abnormal tissue masses that protrude into the lumen of the DIGESTIVE TRACT or the RESPIRATORY TRACT. Polyps can be spheroidal, hemispheroidal, or irregular mound-shaped structures attached to the MUCOUS MEMBRANE of the lumen wall either by a stalk, pedunculus, or by a broad base.Feasibility Studies: Studies to determine the advantages or disadvantages, practicability, or capability of accomplishing a projected plan, study, or project.Diagnosis, Computer-Assisted: Application of computer programs designed to assist the physician in solving a diagnostic problem.WisconsinAdenomatous Polyps: Benign neoplasms derived from glandular epithelium. (From Stedman, 25th ed)Patient Preference: Individual's expression of desirability or value of one course of action, outcome, or selection in contrast to others.Cost-Benefit Analysis: A method of comparing the cost of a program with its expected benefits in dollars (or other currency). The benefit-to-cost ratio is a measure of total return expected per unit of money spent. This analysis generally excludes consideration of factors that are not measured ultimately in economic terms. Cost effectiveness compares alternative ways to achieve a specific set of results.Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Tomography, Emission-Computed: Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.Cone-Beam Computed Tomography: Computed tomography modalities which use a cone or pyramid-shaped beam of radiation.Infarction: Formation of an infarct, which is NECROSIS in tissue due to local ISCHEMIA resulting from obstruction of BLOOD CIRCULATION, most commonly by a THROMBUS or EMBOLUS.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Sigmoidoscopy: Endoscopic examination, therapy or surgery of the sigmoid flexure.Observer Variation: The failure by the observer to measure or identify a phenomenon accurately, which results in an error. Sources for this may be due to the observer's missing an abnormality, or to faulty technique resulting in incorrect test measurement, or to misinterpretation of the data. Two varieties are inter-observer variation (the amount observers vary from one another when reporting on the same material) and intra-observer variation (the amount one observer varies between observations when reporting more than once on the same material).Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.