Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography, projectional radiography, and fluoroscopy. Radiocontrast agents are typically iodine, or more rarely barium sulfate. The contrast agents absorb external X-rays, resulting in decreased exposure on the X-ray detector. This is different from radiopharmaceuticals used in nuclear medicine which emit radiation.
Iodinated contrast is a form of water-soluble, intravenous radiocontrast agent containing iodine, which enhances the visibility of vascular structures and organs during radiographic procedures. Some pathologies, such as cancer, have particularly improved visibility with iodinated contrast.
Iotrolan is an iodine-containing radiocontrast agent, a substance used to improve the visibility of body structures on images obtained by X-ray techniques.
An arthrogram is a series of images of a joint after injection of a contrast medium, usually done by fluoroscopy or MRI. The injection is normally done under a local anesthetic such as Novocain or lidocaine. The radiologist or radiographer performs the study using fluoroscopy or x-ray to guide the placement of the needle into the joint and then injects around 10 ml of contrast based on age. There is some burning pain from the anesthetic and a painful bubbling feeling in the joint after the contrast is injected. This only lasts 20 – 30 hours until the Contrast is absorbed. During this time, while it is allowed, it is painful to use the limb for around 10 hours. After that the radiologist can more clearly see what is going on under your skin and can get results out within 24 to 48 hours.
Diatrizoate, also known as amidotrizoate, Gastrografin, is a contrast agent used during X-ray imaging. This includes visualizing veins, the urinary system, spleen, and joints, as well as computer tomography. It is given by mouth, injection into a vein, injection into the bladder, through a nasogastric tube, or rectally.
Myelography is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. Historically the procedure involved the injection of a radiocontrast agent into the cervical or lumbar spine, followed by several X-ray projections. Today, myelography has largely been replaced by the use of MRI scans, although the technique is still sometimes used under certain circumstances – though now usually in conjunction with CT rather than X-ray projections.
Sialography is the radiographic examination of the salivary glands. It usually involves the injection of a small amount of contrast medium into the salivary duct of a single gland, followed by routine X-ray projections.
Pyelogram is a form of imaging of the renal pelvis and ureter.
Iohexol, sold under the trade name Omnipaque among others, is a contrast agent used for X-ray imaging. This includes when visualizing arteries, veins, ventricles of the brain, the urinary system, and joints, as well as during computed tomography. It is given by mouth, injection into a vein, or into a body cavity.
Lymphography is a medical imaging technique in which a radiocontrast agent is injected, and then an X-ray picture is taken to visualise structures of the lymphatic system, including lymph nodes, lymph ducts, lymphatic tissues, lymph capillaries and lymph vessels. Lymphangiography is the same procedure, used only to visualize the lymph vessels. The x-ray film or image of the lymphatic vessels and lymph nodes is called a lymphogram or a lymphangiogram.
Iopamidol (INN), sold under the brand name Isovue among others, is a nonionic, low-osmolar iodinated contrast agent, developed by Bracco Diagnostics.
Metrizamide is a non-ionic iodine-based radiocontrast agent. It is also a density gradient medium for the centrifugation of biological particles.
Iopentol is a pharmaceutical drug that was used as a radiocontrast agent for X-ray imaging in Europe.
Iobitridol is a pharmaceutical drug used as an iodine-based radiocontrast agent in X-ray imaging. It is injected into blood vessels, joints, or body cavities such as the uterus, and filtered out by the kidneys. Its most common adverse effect is nausea. Severe allergic reactions are rare.
Metrizoic acid is a pharmaceutical drug that was used as an iodinated contrast medium for X-ray imaging. Its uses included angiography and urography, but it has been discontinued, at least in the US.
Acetrizoic acid is a pharmaceutical drug that was used as an iodinated contrast medium for X-ray imaging. It was applied in form of its salt, sodium acetrizoate, but is no longer in clinical use.
Iotroxic acid, used in the form of meglumine iotroxate, is a molecule used as a contrast medium during X-rays. It is specifically used during tests looking at the gallbladder and biliary tract. It is given by slow injection into a vein.
Organoiodine chemistry is the study of the synthesis and properties of organoiodine compounds, or organoiodides, organic compounds that contain one or more carbon–iodine bonds. They occur widely in organic chemistry, but are relatively rare in nature. The thyroxine hormones are organoiodine compounds that are required for health and the reason for government-mandated iodization of salt.
Contrast CT, or contrast enhanced computed tomography (CECT), is X-ray computed tomography (CT) using radiocontrast. Radiocontrasts for X-ray CT are generally iodine-based types. This is useful to highlight structures such as blood vessels that otherwise would be difficult to delineate from their surroundings. Using contrast material can also help to obtain functional information about tissues. Often, images are taken both with and without radiocontrast. CT images are called precontrast or native-phase images before any radiocontrast has been administered, and postcontrast after radiocontrast administration.
Carbon dioxide angiography is a diagnostic radiographic technique in which a carbon dioxide (CO2) based contrast medium is used - unlike traditional angiography where the contrast medium normally used is iodine based – to see and study the body vessels. Since CO2 is a non-radio-opaque contrast medium, angiographic procedures need to be performed in digital subtraction angiography (DSA).
