What is contrast media and when is it used?
Contrast media (CM) are used in imaging techniques to enhance the differences between body tissues on images. The ideal contrast medium should achieve very high concentration in the tissues without producing any adverse effects. Unfortunately, this has not been possible so far and all CM have adverse effects. The increasing use of CM is likely to give rise to a wide range of pitfalls, including compliance with and appropriateness of indications for the use of CM themselves, the choice of the ...
How are contrast media used to produce an image?
Contrast media are substances used to highlight areas of the body in radiographic contrast to their surrounding tissues. Contrast media enhance the optical density of the area under investigation so that the tissue/structure absorption differentials are sufficient to produce adequate contrast with adjacent structures, enabling imaging to take place.
What does contrast media mean?
The meaning of CONTRAST MEDIUM is a substance (as a solution of iodine or suspension of barium sulfate) comparatively opaque to X-rays that is introduced into the body (as by injection or swallowing) to contrast an internal part (as the gastrointestinal tract, kidneys, or blood vessels) with its surrounding tissue in radiographic visualization —called also contrast agent, contrast material.
What does contrast medium mean?
contrast medium, contrast material noun. a substance that is opaque to x-rays; when administered it allows a radiologist to examine the organ or tissue it fills.
What is contrast media and its type?
The two main types of iodine-based contrast media are ionic and nonionic. The development of ionic contrast media in the 1920s and 1930s allowed radiologists to visualize vessels and organs on various imaging studies.
What are examples of contrast media?
Saline (salt water) and gas (such as air) are also used as contrast materials in imaging exams. Microbubbles and microspheres have been administered for ultrasound imaging exams, particularly exams of the heart.
What is meant by contrast study?
Contrast radiography is a method of studying organs using X-rays and the administration of a special dye, called a contrast medium. This test allows the radiologist to evaluate structures that are not clearly evident on conventional X-ray exams.
How does contrast media work?
Contrast material works by temporarily changing the way the imaging machine interacts with the body. Some types of contrast slow down x-ray beams. Other types of contrast temporarily affect the magnetic properties of certain atoms inside your body.
What are the 4 types of contrast media?
There are three broad kinds of contrast available: IV, PO, and PR (rectal). IV contrast is either gadolinium for MRI or iodinated contrast for CT. PO contrast for all ER and inpatient CT scans is dilute iodinated contrast (same agent used for IV contrast in CT).
What are the five properties of contrast media?
Characteristics of Radiopaque Contrast Media In the selection of a radiopaque contrast agent, certain characteristics such as viscosity, toxicity, iodine content, miscibility, and persistence must be considered.
Why is contrast media used in radiology?
Contrast media (CM) are used in imaging techniques to enhance the differences between body tissues on images. The ideal contrast medium should achieve very high concentration in the tissues without producing any adverse effects.
What is the unit of contrast?
Because it's a ratio, there is no unit for contrast. Instead, contrast is normally expressed as 'X : 1,' with 'X' being how many times brighter white is than black.
Who discovered contrast media?
Torsten AlménTorsten Almén (1931-2016): the father of non-ionic iodine contrast media. Acta Radiol. 2016 Sep;57(9):1072-8. doi: 10.1177/0284185116648504.
Why do we use contrast?
Contrast distinguishes, or “contrasts,” between organs, tissues, bones, or blood vessels during your imaging exam. It doesn't change any of these things, but it changes how your X-ray, CT, or MRI scan sees them. Contrast is important because it helps radiologists distinguish between normal and abnormal conditions.
Why is contrast used in CT?
A special dye called contrast material is needed for some CT scans to help highlight the areas of your body being examined. The contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines or other structures. Contrast material might be given to you: By mouth.
What type of contrast is used in CT?
The most common contrast agents used with CT imaging are barium- and iodine-based. The specific agent and route of administration are based on clinical indications and patient factors.
What are the four types of contrast media administered in CT?
There are four types of contrast agent used in CT:The type that is given via intravenous (through a vein) injection.The type that is given orally.The type that is given rectally.A much less common type of contrast used in CT is inhaled as a gas and used for special lung and brain imaging.
What is positive contrast media?
POSITIVE CONTRAST MEDIA. Barium and iodine preparations are the commonest positive contrast media, appearing radiopaque due to their high atomic numbers (56 and 53 respectively). Barium is presented as barium sulphate and iodine as complex organic molecules.
What is positive and negative contrast media?
Positive contrast media has a higher attenuation density than the surrounding tissue. This means that the contrast looks more opaque than the surrounding tissue when seen on an x-ray. Negative contrast media has a lower attenuation density than the surrounding tissue.
What is contrast media quizlet?
diagnostic agents instilled into body orifices or injected into vascular system, joints, and ducts to enhance subject contrast in anatomic areas where low subject contrast (similar density to their surrounding structures) exists. Note: not a dye; it doesn't color anything! RadioLUCENT Contrast ⊖
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Why is radiographic CM used?
Radiographic CM are used in imaging examinations to aid in the characterization, detection, and staging of disease. Although the CM currently in use have strong documented safety profiles, their use is not completely without risk.
What is CM in medical imaging?
Widespread use of medical imaging has led to a significant increase in the use of radiologic contrast media (CM). Half of the estimated 78 million computed tomography (CT) examinations and 37 million magnetic resonance imaging (MRI) examinations performed annually in the United States include the use of CM. Radiographic CM are used in imaging examinations to aid in the characterization, detection, and staging of disease. Although the CM currently in use have strong documented safety profiles, their use is not completely without risk. According to the World Health Organization, an adverse drug reaction is a harmful, unintentional, and often unavoidable response to normal therapeutic doses of a medicine. In general, most patients who receive a contrast agent have no adverse reactions (ARs), and when a reaction does occur it is usually mild and self-limiting. Therefore, establishing preventive measures against ARs from CM is essential for patient safety. Awareness of the various reactions that can occur and prompt management are critical in reducing the likelihood of an adverse outcome. Rapid evaluation and treatment of ARs requires adequate training, readily available equipment, and appropriate medications. This chapter discusses the important aspects of screening, recognizing, and managing the risks central to intravenously administered CM.
How is CM administered?
CM administration depends on the clinical indication, vascular access, and type of examination. The method of CM delivery (hand injection vs. power injection) also varies depending on the requested procedure. Stable intravenous (IV) access is always necessary, and recognizing the importance of proper technique is critical to avoid potentially serious complications. Careful preparation of the power injection apparatus is crucial to minimize the risk of complications ( Box 20.1 ). Power injection of IV CM should be through a flexible plastic cannula; metal needles must always be avoided. Vascular access guidelines for CM administration at our institution can be seen in Box 20.2 . Power injection of CM through some central venous catheters can be performed safely, provided that certain precautions are followed ( Box 20.3 ). Furthermore, obtaining the patient’s full cooperation throughout the injection process is important to avoid or promptly identify a complication should one occur. The injection should always be discontinued if the patient reports pain or sensation of swelling at the injection site. Although not an adverse reaction of CM, a clinically significant venous air embolism can occur when IV CM is administered by hand injection. Venous air embolisms are potentially fatal but extremely rare complications commonly seen in the intrathoracic veins, main pulmonary artery, and right ventricle, and they appear as air-fluid levels or air bubbles on contrast-enhanced CT. Unintentional injection of large amounts of air into the venous system may result in dyspnea, expiratory wheezing, chest pain, cough, tachycardia, pulmonary edema, and hypotension. Stroke leading to neurologic deficits may also occur due to decreased cardiac output or paradoxical air embolism. Administering 100% oxygen and placing the patient in the left lateral decubitus position is the mainstay of treatment. To further reduce the size of air bubbles and help restore circulation and oxygenation, hyperbaric oxygen can be given. Closed-chest cardiopulmonary resuscitation should be started immediately if cardiopulmonary arrest occurs.
Can contrast media cause a reaction?
Most patients who receive contrast media have no adverse reactions, and when a reaction does occur it is usually mild and self-limiting. Rarely, contrast media use may result in a moderate or severe reaction that can be life-threatening. Therefore, establishing preventive measures and increasing awareness of the various reactions are critical ...
Is contrast media safe?
The contrast media being used today have strong documented safety profiles, but their use is not without risk. Most patients who receive contrast media have no adverse reactions, and when a reaction does occur it is usually mild and self-limiting. Rarely, contrast media use may result in a moderate or severe reaction that can be life-threatening. Therefore, establishing preventive measures and increasing awareness of the various reactions are critical to reduce the likelihood of an adverse outcome. This chapter discusses the important aspects of screening, recognizing, and managing the risks that are central to intravenously administered contrast media.
Can you inject contrast media through a power injector?
Contrast media should not be administered by power injector through small-bore, peripheral (e.g., arm) access central venous catheters (unless permitted by the manufacturer’s specifications) because of the risk of catheter breakage. It cannot be assumed that all vascular catheters including a peripherally inserted central catheter can tolerate a mechanical injection. A number of manufacturers have produced power injector–compatible vascular catheters. The manufacturer’s specifications should be followed.
Why do we use contrast materials?
Contrast materials improves visibility of blood vessels, tissues and specific organs to help doctors diagnose medical conditions. Contrast materials enter your body in one of three ways for the test:
How does contrast material help a radiologist?
Contrast material enhances and improves the quality of these images. Contrast material can also improve the quality of some ultrasound and x-rays. In many cases, the use of contrast can help the radiologist distinguish normal from abnormal conditions. Contrast material works by temporarily changing the way the imaging machine interacts with ...
What is the most commonly used contrast material for MRI?
Gadolinium. Gadolinium is the key component in the most frequently used MRI contrast material. MRIs use powerful magnets that affect protons, which are parts of a proton that have a positive electrical charge.
What is the best contrast material for ultrasound?
Saline (salt water) and air also make good contrast materials in imaging exams. Ultrasound imaging, especially ultrasound imaging of the heart, may use microbubbles and microspheres that help organs and tissues appear brighter on ultrasound.
What organs do you need contrast injections for?
Clinicians order the intravenous injection of iodine-based contrast to enhance x-ray and CT images of internal organs, such as the heart and lungs, gastrointestinal tract, arteries and veins, the brain, breast tissue and soft tissues of the body, such as muscles and fat.
What are the shadows in x-rays?
In this way, the x-ray beams form "shadows" that represent the tissues and organs on the images. Iodine-based and barium-sulfate contrast materials limit or block the x-rays' ability to pass through the tissue.
How does contrast material enter the body?
Contrast materials enter your body in one of three ways for the test: By mouth. Rectally, by enema. Injected into a blood vessel. Following the imaging exam, your body either absorbs the contrast material or eliminates it through urine or stool. The contrast is not permanent, so it does not discolor your organs forever.
How do contrast materials help?
Contrast materials help distinguish or "contrast" selected areas of the body from surrounding tissue. By improving the visibility of specific organs, blood vessels or tissues, contrast materials help physicians diagnose medical conditions. Contrast materials enter the body in one of three ways. They can be:
Why do doctors use contrast materials?
Contrast materials, also known as contrast agents and contrast media are used to improve the diagnostic value of those imaging exams.
What is the most common contrast material used in MR imaging?
Gadolinium is the key component of the contrast material most often used in magnetic resonance (MR) exams. When this substance is present in the body, it alters the magnetic properties of nearby water molecules, which enhances the quality of MR images. Saline (salt water) and gas (such as air) are also used as contrast materials in imaging exams.
What is used as contrast in ultrasound?
Saline (salt water) and gas (such as air) are also used as contrast materials in imaging exams. Microbubbles and microspheres have been administered for ultrasound imaging exams, particularly exams of the heart. top of page.
How long does it take for bowel movements to go white after a barium sulfate contrast?
Barium-sulfate contrast materials are expelled from the body with feces. You can expect bowel movements to be white for a few days.
Why use contrast enhanced ultrasound?
Contrast-enhanced ultrasound with microbubbles is a convenient, relative ly inexpensive way to improve visualization of blood flow that does not use radiation. It is a useful option for patients with kidney failure or allergies to MRI and/or computed tomography (CT) contrast material.
How long after contrast can you breastfeed?
Manufacturers of intravenous contrast indicate mother s should not breast-feed their babies for 24 to 48 hours after contrast medium is given. However, both the American College of Radiology (ACR) and the European Society of Urogenital Radiology note that the available data suggest that it is safe to continue breast-feeding after receiving intravenous contrast. The Manual on Contrast Media from the ACR states:
What is iodine contrast?
Iodinated contrast media are contrast agents that contain iodine atoms used for x-ray-based imaging modalities such as computed tomography (CT). They can also used in fluoroscopy, angiography and venography, and even occasionally, plain radiography. Although the intravenous route of administration is most common, they are also administered by many other routes, including gastrointestinal (oral, rectal), cystourethral, vaginal, intraosseous, etc.
Why is iodine used as a contrast agent?
As iodine has a high atomic number, 53, compared to most tissues in the body, the administration of iodinated material produces image contrast due to differential photoelectric absorption. Iodine has a particular advantage as a contrast agent because the k-shell binding energy (k-edge) is 33.2 keV, similar to the average energy ...
What is material decomposition in CT?
Material decomposition techniques allows the creation of virtual images in which iodine is preferentially increased in intensity (iodine map) or removed altogether (virtual non-contrast), which can hold additional diagnostic value.
What are the two types of interactions between photons and matter?
The ability to distinguish between tissues of different x-ray attenuation (image contrast) depends upon two types of interactions between photons and matter: Compton scattering and photoelectric absorption. Both these interactions depend upon physical density, but the latter also depends upon atomic number of the matter.
Can iodinated contrast be administered intraosseous?
In the context of the critically ill patient where intraven ous access is not possible, iodinated contrast can be administered via an intraosseous injection. Pressure rates must be high due to the intramedullary pressure within the bone. According to the ACR Committee on Drugs and Contrast Media, there are no reported complications of intraosseous injections at 5 mL/s 6. The humerus is the most commonly accepted site of injection 7,8.
What does "contrast" mean?
Definition of contrast. : to set off in contrast : compare or appraise in respect to differences Contrast European and American manners. Contrast the two major characters of the novel. —often used with to or with contrasting the painter with her contemporaries.
What does contrast mean in a sentence?
1 : to be different especially in a way that is very obvious Her black dress and the white background contrast sharply.
What does "collate" mean in "compare"?
compare, contrast, collate mean to set side by side in order to show differences and likenesses. compare implies an aim of showing relative values or excellences by bringing out characteristic qualities whether similar or divergent. compared the convention facilities of the two cities contrast implies an emphasis on differences. contrasted the computerized system with the old filing cards collate implies minute and critical inspection in order to note points of agreement or divergence. data from districts around the country will be collated
