Biliscopin® Infusion, an iodinated contrast medium for intravenous cholecystography is secreted actively by the hepatocytes. The biliary excretion rate of a biliary contrast medium is determined by the binding to plasma proteins and liver receptor proteins, and by its transport maximum for the liver. Because of its high hepatocellular transport rate, Biliscopin® Infusion leads rapidly to high grade contrast density in the intra-hepatic and extra-hepatic biliary ducts as well as in the gallbladder.
Computed tomography with biliary contrast agents provides maximum quality preoperative imaging of the biliary tract.

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.

Bone densitometry measures the strength and density of bones. Changes in trabecular bone mineral density (BMD) is an early indicator of change in metabolic function. Bone densitometry measures the amount of calcium in regions of the bones. A bone densitometer is used to determine the risk of developing osteoporosis and can also be used to estimate a patient's risk of fracture.
Bone densitometry methods involve:
Dual energy x-rays (DEXA) or CT scans (Osteo CT or QCT) compare the numerical density of the bone (calculated from the image), with empirical data bases of bone density. DEXA is widely available and has an accuracy between those of QCT and ultrasound.

CAT/CT guided biopsies and other minimally invasive interventions are well established medical procedures. Since the beginning of computed tomography, conventional CAT/CT imaging studies has been used to guide an interventional procedure such as a tissue biopsy of a suspected tumor or metastases.
Advanced interventional CT scanners provide fluoroscopic techniques allowing additionally the guidance of minimally invasive surgery or micro-therapy. Fluoro CT allows the continuous monitoring of the needle trajectory or inserted surgical instrument. A wide gantry opening, external tilting laser for needle guidance and special software ease the intervention.
CT images are also used to plan radiotherapy cancer treatment and determine how the disease is responding to the treatment.

(Computed tomography number) The CT number is a selectable scan factor based on the Hounsfield scale. Each elemental region of the CT image (pixel) is expressed in terms of Hounsfield units (HU) corresponding to the x-ray attenuation (or tissue density).
CT numbers are displayed as gray-scale pixels on the viewing monitor. White represents pixels with higher CT numbers (bone). Varying shades of gray are assigned to intermediate CT numbers e.g., soft tissues, fluid and fat. Black represents regions with lower CT numbers like lungs and air-filled organs.