MRI

Magnetic resonance imaging (MRI) is a powerful imaging technology that can create detailed images in three dimensions from inside the human body. It is often used to detect, diagnose, and monitor diseases. The MRI scanner uses cutting-edge technology to stimulate and detect the change in the rotational axis of protons found in water molecules in living tissues.

The development of magnetic resonance imaging (MRI) scans has been a huge milestone for the healthcare community. MRI scans provide much clearer and more detailed images of organs, tissues, and muscles than regular x-rays and CT scans.

MRI can be used to distinguish between white and gray matter in the brain and diagnose aneurysms and tumors. Because it does not use X-rays or other radiation, MRI is often the preferred choice for imaging when repeated scans are required for diagnosis or treatment, especially in the brain.

MRI also has the benefit of providing high-resolution images with excellent contrast between the various tissues. This makes it a valuable tool for research as well as for the diagnosis and treatment of medical conditions.

Contrast agents

The importance of MRI in our lives and the role of contrast agents in improving imaging sensitivity have caused many researchers to try to enhance contrast properties using various techniques to achieve better image contrast.

MRI contrast agents can be taken orally or intravenously and removed from the body through the kidneys. There are two types of contrast agents:

Paramagnetic compounds, like gadolinium, reduce the longitudinal (T1) relaxation property and result in a brighter signal; and super-paramagnetic magnetic nanoparticles (SPMNPs), have a significant impact on transversal (T2) relaxation properties.

Gadolinium contrast agents help to improve the clarity and accuracy of MRI images. By injecting gadolinium contrast into the body, radiologists can better understand how the body works and the presence of diseases or abnormalities.

The gadolinium contrast media molecule is made up of a gadolinium ion and a carrier molecule (a chelating agent) bonded together. The chelating agent inhibits the toxicity of gadolinium while preserving its contrast characteristics.

The gadolinium contrast agent is used to enhance the clarity of MRI images in approximately 1 in 3 cases. This enhances the accuracy of the MRI diagnosis. For example, it increases the visibility of inflammation, tumors, blood vessels, etc.

Contrast agents’ side effects

Although gadolinium-based MRI contrast agents are generally considered to be safe for clinical use, undesirable side effects associated with their use have been reported. Nephrogenic Systemic Fibrosis (NSF) is the most well-known of these effects due to its devastating consequences. Although the exact cause is unknown, NSF is a rare but serious illness that has been linked to the use of gadolinium-containing contrast agents. As a result of this potential risk, the US guidelines recommend that patients on dialysis receive gadolinium agents only when they are essential, and dialysis should be done as soon as possible after the exam to remove the agent from the body. In patients who have normal kidney function, most of the injected gadolinium contrast is passed out in the urine within 24 hours, while other side effects in subjects with normal renal function include hypersensitivity, nausea, and chest pain.

Radiology departments often express concern about the use of gadolinium-based contrast agents in pregnant or lactating women, as exposure of a fetus or newborn to drugs is not ideal. It is best to avoid MRI scans during pregnancy, particularly in the first trimester, when the organs of the fetus are forming. Contrast agents, if used, have the potential to enter the fetal bloodstream and cause harm. Lately, it has come to light that even small amounts of gadolinium contrast (1% or less of what’s injected) can stay in tissues, mostly in bones, with trace amounts in the brain. Currently, no harmful effects of these small amounts of retained gadolinium are known. Additionally, contrast media is becoming an increasingly pressing environmental issue, as it contaminates sources of drinking water in many places worldwide. Because of these findings, radiologists are more judicious in recommending gadolinium contrast, only using it when it is likely to assist in the diagnosis.