Everything about the contrast material types

17-07-2017

During certain MRI (Magnetic resonance imaging) and CT (Computed tomography) scans, the operator gives contrast agent to our patients. The method, and the amount of the given contrast material always depends on the type of the test.

What is the contrast agent used for?

Contrast dye is suitable for differentiating the normal and diseased conditions from each other.

What types of contrast material exist?

Intravenous injection

Method

The CT-MR operator injects the contrast media into a vein. The injection can happen at the beginning -, or during the exam.

Injected dose and speed

The injected amount and the speed can be determined in advance. It is the task of the CT-MR operator to specify it, considering the type of the test, the examined body part and the patient’s weight. It is important for our patients to give their body weight before CT and MR scans.

Timing of injection

It depends on the scanned part of the body and the type of the test. In case of CT, the injection of the contrast agent begins a few minutes after the exam starts. As for MRI, it takes place in the second half of the test. The operator informs the patient of the expected time of injection in advance.

What is the difference between intravenous contrast agents for CT and MRI?
- CT scan: Throughout the CT scan, the operator uses iodine contrast agent. After the injection, the patient can feel warmth, bitter taste, and an urge to urinate. Larger dose can be used (from 30 to 120 ml) depending on the patient’s weight and the type of the test.
- MRI scan: MRI contrast agent is gadolinium based. In this case the technician uses lower dose (5-15 ml)

It is important to emphasize if someone sensitive to the CT contrast agent, it doesn’t mean that the patient cannot receive the MRI contrast material.

Contrast agents taken by orally (liquid)

Before certain types of examinations (such as the abdominal exams) it is essential to swallow the contrast material as a liquid. These are small amounts of contrast agents dissolved in water. It’s side effect can be a slight diarrhea.