Interventional radiology is an area of clinical subspecialty which uses various radiology techniques (such as fluoroscopy, ultrasound, computed tomography, and MRI procedures) to guide procedures such as a biopsy, inserting catheters, place wires, draining fluids, dilating or stenting narrowed ducts or vessels to diagnose or treat different conditions.

See also CT Guided Biopsy, Angioplasty, Coronary Angiogram and Interventional Ultrasound.

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.

(Radioactive Seed Implantation Therapy) Brachytherapy is a type of radiation therapy in which a sealed source (encapsulated radionuclide) is placed inside the patient as close as possible to the area being treated. The brachytherapy source delivers usually gamma or beta radiation at a distance up to a few centimeters either by surface, intracavitary or interstitial application.

See also Low Dose Rate, Cryotherapy, RF Thermal Ablation and Prostate Ultrasound.

(CA) Contrast agents are used to change the imaging characteristics, resulting in additional information about anatomy, morphology or physiology of the human body. Radiocontrast agents (also called photon-based imaging agents) are used to improve the visibility of internal body structures in x-ray and CT procedures. Contrast agents are also used to increase the contrast between different tissues in MRI (magnetic resonance imaging) and ultrasound imaging. The ideal imaging agent provides enhanced contrast with little biological interaction.
First investigations with radiopaque materials are done shortly after the discovery of x-rays. These positive contrast agents attenuate x-rays more than body soft tissues due to their high atomic weight. Iodine and barium have been identified as suitable materials with high radiodensity and are used until today in x-ray and CT contrast agents. Iodine-based contrast agents are water-soluble and the solutions are used nearly anywhere in the body. Iodinated contrast materials are most administered intravenous, but can also be introduced intraarterial, intrathecal, oral, rectal, intravesical, or installed in body cavities. Barium sulfate is only used for opacification of the gastrointestinal tract. Negative contrast agents attenuate x-rays less than body soft tissues, for example gas.

Iodinated contrast media are differentiated in;

Intravascular iodinated contrast agents are required for a large number of x-ray and CT studies to enhance vessels and organs dependent on the blood supply. Injectable contrast agents are diluted in the bloodstream and rapidly distributed throughout the extracellular fluid. The main route of excretion is through the kidneys, related to the poor binding of the agent to serum albumin. The liver (gall bladder) and small intestine provide alternate routes of elimination particularly in patients with severe renal impairment. The use of special biliary contrast agents is suitable for gallbladder CT and cholecystograms because they are concentrated by the liver to be detectable in the hepatic bile.
The introduction of fast multi-detector row CT technology, has led to the development of optimized contrast injection techniques. The amount of contrast enhancement depends on the contrast agent characteristics, such as iodine concentration, osmolality, viscosity, and the injection protocol, such as iodine flux and iodine dose. Adverse reactions are rare and have decreased with the introduction of nonionic contrast agents.
See also Contrast Enhanced Computed Tomography, Abdomen CT, Contrast Media Injector, Single-Head CT Power Injector, Multi-Head Contrast Media Injector, Syringeless CT Power Injector, CT Power Injector.

A coronary angiogram (or cardiac catheterization) is the radiographic visualization of the coronary arteries after the introduction of a contrast agent. A coronary angiography can be performed for both diagnostic and interventional (treatment) purposes.
A catheter, inserted into a major blood vessel has to be maneuvered up to the coronary arteries to inject a blood compatible iodinated contrast material (dye). The x-ray visible catheter allows injecting a small amount of contrast agent selectively in the coronary arteries or the heart chambers. Continuous images are recorded (movies or cineangiogram) in multiple views from different angles are in order to ascertain the precise location and severity of coronary artery blockages. Digitized images are also saved on computer and replayed onto a video screen as needed.
A coronary angiogram is more invasive and requires more patient recovery time than coronary CT angiography. In the past, the gold standard for detecting atherosclerotic plaque was a coronary angiography and intravascular ultrasound. Today, the American Heart Association considers CT scanning to be one of the most effective, non-invasive methods for the detection of calcification in the coronary arteries.

See also Interventional Radiology.