The molecular structure of some iodinated contrast agents makes them suitable for the computer-tomographic examination of the biliary tract. Organic iodine compounds increase the attenuation of x-rays and the contrast between body tissues containing iodine and those tissues that do not contain iodine. The degree of opacification is directly proportional to the concentration and volume of the iodinated contrast agent (the total amount of iodine).
Biliary contrast agents can be taken orally, for example calcium iopodate, or intravenous meglumine iotroxate. The contrast media are excreted by the liver and concentrate in the gallbladder after passing the intrahepatic biliary tree and cystic duct.
Oral biliary contrast agents usually opacify the gallbladder after a few hours. If the gallbladder is removed, an intravenous cholegraphic agent is required and gallbladder CT can start 60 minutes after the beginning of contrast medium infusion.
The main limitation of the use of biliary contrast agents is the high rate of allergic reactions and of renal or hepatic toxicity. Caused by the potential for systemic toxicity with intravenous cholangiography, ultrasonography should be the preferred method for evaluation of the gallbladder and the bile ducts.

[Binary Numeral System] Numerical system based on two different states, usually represented by the two symbols 0 and 1. Information storage and processing in modern computers is based on this system. Here the smallest unit is a bit.

See Bit, Byte.

A biopsy is a procedure in which tissue samples are collected. This can be done with a needle, which is inserted into the abnormal area.
An example is the needle breast biopsy. Needle biopsies are usually guided by different imaging techniques like ultrasound, computed tomography, or magnetic resonance imaging. Stereotactic-assisted breast biopsies use computer maps to guide the needle. The location of the breast lump is provided from digital mammograms taken from two angles.
The cells can be removed and examined under a microscope to determine whether the abnormality is cancerous.

See also CT Guided Biopsy.

Each pixel in a digital image has a bit range, which informs the computer which color (or shade of gray) the pixel will display.

The primary login terminal on the host computer used to start software.