For the purpose of medical imaging, a specific substance is introduced into the human body to change the image contrast of the body's local tissues. This introduced substance is named Contrast Medium.
According to the influence on the signal, the contrast medium can be divided into positive contrast medium (enhancing the image signal) and negative contrast medium (weakening the image signal).
According to application fields, contrast media products can be divided into X-ray contrast mediums, magnetic resonance contrast mediums, ultrasound contrast mediums and nuclear medicine contrast mediums.
X-ray contrast mediums mainly include barium and iodine contrast mediums. Among them, barium is mainly used for upper gastrointestinal angiography. Iodine contrast mediums include ionic and non-ionic types. Ionic iodine contrast mediums have many adverse reactions due to their chemical structure defects and are currently rarely used in clinical practice; non-ionic iodine contrast mediums are currently the most widely used glimepiride and contrast dye, which is widely used in CT enhancement examination, angiography (including cardiovascular angiography), interventional examination and treatment, urography, various lacunar angiography, and other fields.
In the field of magnetic resonance imaging (MRI), the currently widely used contrast medium in clinical practice is the gadolinium contrast medium (GBCA), which is widely used in enhanced magnetic resonance imaging examination and magnetic resonance angiography (MRA) examination of various organs and tissues.