MRIkontrastmittel

MRI contrast agents, also known as MRI contrast media or MRI contrast enhancers, are substances administered to patients undergoing magnetic resonance imaging (MRI) scans to improve the visibility of specific tissues or lesions. These agents work by altering the magnetic properties of nearby water molecules, thereby changing the signal intensity on the MRI images. This contrast enhancement can help radiologists distinguish between normal and abnormal tissues, such as tumors or areas of inflammation, and better define anatomical structures.

The most commonly used MRI contrast agents are based on gadolinium, a paramagnetic metal. When gadolinium is chelated, meaning it is bound to other molecules to form a stable complex, it can be safely injected intravenously. These gadolinium-based contrast agents (GBCAs) shorten the T1 relaxation time of water molecules in their vicinity, leading to a brighter signal on T1-weighted MRI sequences. Other types of contrast agents exist, including those based on iron oxide particles, which can alter T2 relaxation times and appear darker on T2-weighted images.

Before administering an MRI contrast agent, a healthcare professional will assess the patient's medical history, particularly kidney function, as most contrast agents are excreted by the kidneys. Allergies to contrast media are rare but possible. While generally safe, potential side effects can occur, ranging from mild reactions like headache or nausea to more serious but infrequent events such as nephrogenic systemic fibrosis (NSF) in patients with severe kidney disease, or contrast-induced allergic reactions. Newer formulations and guidelines aim to minimize these risks. The decision to use contrast enhancement is made on an individual basis by the referring physician and radiologist to optimize diagnostic accuracy for the specific clinical question.