In the diagnosis and treatment of diseases, medical imaging methods, such as MR imaging, x-ray, PET, SPECT, magnetic x-ray computed tomography photography, EIT and Delta-flash photography and CT scan, it is becoming an increasingly important tool. Some imaging technology is totally dependent on the components of the body (such as bone and soft tissue) inherent property to get the image differences between these components. While some other imaging techniques require the use of drugs (contrast agent) in order to achieve this distinction, or improving the different component parts or between the image contrast between normal tissue and injured tissue.
In most forms of imaging contrast agents have been used.
However, the contrast agent's effectiveness depends not only on its inherent ability to improve image contrast in the above-mentioned imaging modalities, but also depends on its pharmacokinetics, after the Administration, distribution of space and time.
Typically, when after a contrast agent into the body's vascular system, hydrophilic molecules with low molecular weight (such as the molecular weight of less than 50000) distribution to the extracellular fluid (ECF) and Glomerular filtration, fast excretion from the kidneys, particles, liposomes or lipophilic molecules quickly accumulated in the liver.
ECF and liver contrast agent has been put on the market or in clinical practice has been applied. And the blood pool agent (that is, not distributed to the ECF and can stay a long time in a pool of blood reagent) currently has appeared, but the development of these reagents have not made much progress.
Therefore, in MR imaging in the field of early blood pool agents including the ParaMagnetic chelate-macromolecular conjugate of, for example, the large molecules molecular weight of water-soluble substances such as biological tolerance over the renal threshold of dextran and the chelate is a GdDTPA situation. Later proposed the use of poly many chelating agents are able to chelate (for example 20-100) high molecular weight water-soluble ParaMagnetic metal ions chelating agents.
These substances have a lot of questions raised by, for example, the lack of identification of its characteristics cannot predict the distribution of biological; blood pool retention time is not satisfactory; liver volume and not through the glomerulus full bio-clear.
Previous: No Information
Next: NMR methods