MRI contrast agents may be categorised according to Review therefore, aims to classify the MRI contrast agentsĭiscovered to date into relevant groups and to also discuss theirĪpplications, structures, mechanisms of action, pharmacokinetics Of contrast agents for clinical use is under strict scrutiny. Performed nowadays are contrast-enhanced studies, and this is aĪgents are constantly being discovered and investigated. Using ferric chloride as the contrast agent in the gastrointestinalĮt al first proved the use of a gadolinium compound as aĭiagnostic intravascular MRI contrast agent ( 2). The first contrast-enhanced human MRI study was reported in 1981 Shortly after the introduction of clinical MRI, Widely used to increase the contrast difference between normal andĪbnormal tissues. Magnetic resonance imaging (MRI) contrast agents are Some agents are also capable of targeting other organs, inflammation as well as specific tumors. A number of contrast agents have been developed to selectively distinguish liver pathologies. According to biodistribution and applications, MRI contrast agents may be categorised into three types: extracellular fluid, blood pool and target/organ-specific agents. MRI contrast agents may be administered orally or intravenously. MRI contrast agents incorporating chelating agents reduces storage in the human body, enhances excretion and reduces toxicity. The enhanced parts appear darker on T2-weighted images. Dysprosium, superparamagnetic agents and ferromagnetic agents are negative contrast agents. These agents shorten the T1, so the enhanced parts appear bright on T1-weighted images. Most paramagnetic contrast agents are positive agents. These elements shorten the T1 or T2 relaxation time, thereby causing increased signal intensity on T1-weighted images or reduced signal intensity on T2-weighted images. The majority of these agents are either paramagnetic ion complexes or superparamagnetic magnetite particles and contain lanthanide elements such as gadolinium (Gd3+) or transition metal manganese (Mn2+). Magnetic resonance imaging (MRI) contrast agents are categorised according to the following specific features: chemical composition including the presence or absence of metal atoms, route of administration, magnetic properties, effect on the magnetic resonance image, biodistribution and imaging applications.
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