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Contrast Agents Used In Magnetic Imaging Techniques

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Contrast agents are used in many Magnetic resonance imaging procedures to help in identifying the interior anatomy by improving the quality of images. Traditionally, contrast agents can be divided into two groups according to their effect on relaxation times. T1 longitudinal relaxation time can be enhanced by Mn+2 chelates, while T2 transverse relaxation time is can be enhanced by iron oxide nanoparticles. New contrast agents have been developed during the last decades showed some benefits in the field of molecular imaging called smart contrast agents. These agents allows to trigger some active molecules within a cellular environment or a physiological response in a tissue. Any smart agent in order to be used in vivo must show a …show more content…

The researchers developed it by linking Gd+3 (DO3A) to chelators that have low affinity. These chelators can ease the process of contrast agent synthesis. They chose them over the high affinity chelates to avoid accumulation of the indicator when the amount of ca+2 exceeds 1 µM. the chelators that were used are APTRA which have a limitation in their ability to detect fast ca+2 changes. In order to obtain the quantitative results. Firstly, they tested the synthesized contrast medium in vitro using KMOPS buffer at 400 MHz. The relaxivity showed an increase up to 97% after adding 1 equivalent of ca+2. More over and above, they tested the Gd-DOPTRA's selectivity to ca+2 by adding Mg+2 and Zn+2 to the solution. In the presence of Mg+2, the recorded relaxivity was 70%, while it was 49% when they added the Zn+2 to the buffer, and it reached 70% when they increased the amount of Ca+ that presents in that buffer; that means the developed contrast agent is highly selective to ca+2 even in the presence of Mg+2 and Zn+2. Secondly, they administered it in artificial cerebro spinal fluid (ACSF) at 37 Celsius. It recorded 36% selectivity and relaxivity. Finally they proved that the core factor which responsible for the relaxivity variations in different solutions is the hydration number2. In contrast, in 2010 Ilgar Mamedov and his colleagues synthesized a smart agent that can handle the ca+2 changes and variations. Its

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