Contrast dye is a product that can be used in some imaging tests , for example MRI, computed tomography (CAT) or X-ray. There are several chemicals products that can be used as contrast. The choice depends on the imaging technique and on what will be studied evaluated by the doctor. The purpose of contrast dye administration is to highlight organs and tissues that would not appear so clearly in the same imaging test carried out without contrast. Thus, contrast increases the diagnostic acuity of an imaging test; In many cases, contrast administration is essential to make a differential diagnosis, that is, to distinguish between two or more possible situations. Contrast administration Contrast dye may be administered before an exam and/or during an exam. The routes of administration used are: Intravenous; Oral; Rectal. In the same exam, it may be necessary to administer the contrast for more than one of these routes. The decision on the time and route of administration for the contrast depends on the imaging technique and the area of the body that will be analyzed. Contrast dye safety Contrasts products are safe and, as a rule, well tolerated. This means that most people will have contrast-enhanced imaging tests without having any problems. However, some people may be allergic to contrast and have an allergic reaction, which may have varying severity. Severe allergic reactions to a contrast dye are rare and generally occur shortly after the administration, within a period when people are still in the exam room, and clinical teams are prepared for any necessary intervention. Although they are also rare, in mild allergic reactions the most common symptoms include heat sensation, itchy skin, nausea or vomiting, symptoms that almost always resolve without intervention. It's important to know Being allergic to a contrast dye does not mean that you are allergic to all other contrast dyes. It is not true that people allergic to shellfish cannot have contrast-enhanced imaging tests. Current scientific evidence does not demonstrate a relationship between shellfish allergy and the allergic reaction to iodinated contrast. In any person, the risks and benefits of contrast use in an imaging test are assessed by the clinical team, which considers: The patient clinical situation; Personal history and possible limitations, such as previous allergic reactions. Do not forget to read carefully the information provided before being submitted to a medical test. If you have any doubts, clarify them with the clinical team that will carry out the exam. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
