Contrast Techniques of GI Tract, Biliary Tract, Genito Urinary Tract In Radio Diagnosis

Xray and other imaging contrast studies visualize the entire gastrointestinal tract from pharynx to rectum and are most useful for detecting mass lesions and structural abnormalities (eg, tumors, strictures). Singlecontrast studies fill the lumen with radiopaque material, outlining the structure. Better, more detailed images are obtained from doublecontrast studies, in which a small amount of highdensity barium coats the mucosal surface and gas distends the organ and enhances contrast. The gas is injected by the operator in doublecontrast barium enema, whereas in other studies, intrinsic gastrointestinal tract gas is adequate. In all cases, patients turn themselves to properly distribute the gas and barium. Fluoroscopy can monitor the progress of the contrast material. Visualization of the gastrointestinal tract with ultrasound may be difficult because intraluminal air produces an echogenic shadow, which prevents the sound beam from penetrating structures posteriorly. The scattering and reflection