Contrast material In Imaging Procedure

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CONTRAST MATERIAL USED IN MEDICAL IMAGING:Frequently Asked Questions

Q: What is iodinated contrast material?

A. Iodinated contrast material or “x-ray dye” is used in many diagnostic medical imaging examinations, such as computed tomography (CT), excretory urography (IVP), angiography, myelography, hysterosalpingography, arthrography, cystography, sialography, and other miscellaneous procedures. In the case of MRI, many patients receive an injection of MRI contrast (Gadolinium), which is completely different than iodinated contrast and which has almost no risk. Iodinated contrast is administered by intravenous injection through a small IV placed in an arm vein. The contrast circulates in the bloodstream and is eliminated by the kidneys. Occasionally you may feel a warm sensation or feel nauseated for a few seconds. This is a normal reaction.

Q: What type of iodinated contrast does Radiology Medical Group use in their patients?

A: For several years RMG has been using the absolutely safest contrast available, called nonionic low osmolar contrast. This contrast is more costly than conventional ionic high osmolar contrast, but has fewer side effects.

Q: Are there adverse side effects from iodinated contrast material or x-ray dye?

A: Yes, but they are rare. Millions of intravascular X-ray dye injections for medical imaging examinations are given safely each year in North America. RMG currently uses the safest possible x-ray dye (called non-ionic contrast), but adverse reactions may occur. Mild reactions such as nausea, vomiting and skin hives occur in 1% to 3% of patients. Severe adverse reactions are very rare, occurring in 1 of 6250 examinations using nonionic contrast material. Fatal reactions may occur in 1 of 100,000 patients.

Q: Is there risk to MRI contrast (Gadolinium)?

A: Gadolinium MRI contrast media has been approved for use since the late 1980’s and has been extremely well tolerated by the patients all over the world. Severe anaphylactoid reactions to this agent are extremely rare and occur with a much lower frequency than is observed with iodinated contrast material.

Q: What is the risk of oral and other gastrointestinal contrast agents?

A: The oral contrast agents administered at RMG for CT scans of the abdomen and pelvis contain barium, which is iodine-free and has no adverse side effects. Barium is also the preferred gastrointestinal contrast for upper GI series and barium enemas. Occasionally, in certain medical conditions, iodine-based contrast agents are preferred for upper and lower GI exams, but use of iodine-based contrast material in these parts of the body has even less risks than the already low risk of intravenous contrast injection.

Q: Is iodinated contrast used in other medical imaging exams?

A: Yes. There are some medical imaging exams utilizing “x-ray dye” in which the contrast is not injected intravenously, but rather is injected into the spinal canal (myelogram), bladder (cystogram), uterus (hysterosalpingogram), or joint space (arthrogram). Use of contrast material in these parts of the body has even less risks than the already low risk of intravenous contrast injection.

Q: How do I know if I am at increased risk for a contrast reaction?

A: Certain patients are at higher risk for experiencing a reaction. You must notify our staff if you have a history of iodine allergy, previous reaction to x-ray dye, a history of severe or multiple allergies, asthma, heart disease, diabetes, kidney disease, multiple myeloma, sickle cell anemia or pheochromocytoma. Upon arriving at the imaging center, you will be asked to complete a patient screening form regarding possible risks for intravenous injection of contrast material.

Q. What can I do if I have a history of iodine allergy or previous reaction to contrast material?

A: Discuss this with your personal physician who may need to consult with a RMG radiologist to determine which examination is best for you. If you require a CT scan, that exam may not necessarily require intravenous contrast. In addition, if you are not a candidate for intravenous contrast use, there may be alternative tests such as ultrasound or MRI (Magnetic Resonance Imaging).

Q: If I still require an exam with iodinated contrast, what can be done to minimize a reaction?

A: If you have a history of a previous severe reaction including wheezing, difficulty breathing, or anaphylactic shock, then your examination should be performed in a hospital outpatient radiology department, and your physician will need to speak with one of our radiologists to plan your examination. If you have a history of a mild previous reaction (such as hives or skin rash), you will receive medication (corticosteroid and antihistamine) prior to the contrast procedure and receive the safest possible contrast—low osmolar nonionic contrast. This premedication regimen is simple and has no side effects. Although it has been shown to reduce the likelihood of a severe reaction, no such regimen has completely eliminated repeat reactions. For further details of the premedication protocol, click here.

Q: If I have a history of previous mild iodine or contrast reaction and I need a miscellaneous procedure such as a hysterosalpingogram, myelogram, or arthrogram, do I still require premedication?

A: Yes. Even though the use of iodinated contrast in these parts of the body does not require an intravenous injection and has even less risk than an intravenous injection, premedication before your exam is recommended.

Q: If I am taking Metformin (Glucophage) for diabetes, can I receive contrast material?

A: Yes, but only if certain precautions are taken and if there are no other contraindications to iodinated contrast material, such as abnormal renal function or history of previous contrast reaction. Metformin (Glucophage) is an oral antihyperglycemic agent used to treat patients with non-insulin-dependent diabetes. There is an uncommon but serious adverse effect of lactic acidosis, possibly leading to death, in patients who do not discontinue their Metformin medication following injection of contrast material. Metformin (Glucophage) must be discontinued before or at the time of the contrast injection, and withheld for 48 hours after the injection. If you have any questions regarding this medication interruption or the management of your diabetes during this time period, please contact your personal physician.

Reference: Manual on Contrast Media, 4th Edition, American College of Radiology, October 1998.

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