Contrast Agents I: Magnetic Resonance Imaging (Topics in Current Chemistry (221))

Extracellular MRI and X-ray contrast agents are characterized by their phar- cokinetic behaviour.After intravascular injection their plasma-level time curve is characeterized by two phases. The agents are rapidly distributed between plasma and interstitial spaces followed by renal elimination with a terminal half-live of approximatly 1–2 hours. They are excreted via the kidneys in unchanged form by glomerular filtration. Extracellular water-soluble contrast agents to be applied for X-ray imaging were introduced into clinical practice in 1923. Since that time they have proved to be most valuable tools in diagnostics.They contain iodine as the element of choice with a sufficiently high atomic weight difference to organic tissue. As positive contrast agents their attenuation of radiation is higher compared with the attenuation of the surrounding tissue. By this contrast enhancement X-ray diagnostics could be improved dramatically. In 2,4,6-triiodobenzoic acid derivatives iodine is firmly bound. Nowadays diamides of the 2,4,6-triiodo-5-acylamino-isophthalic acid like iopromide (Ultravist, Fig. 1) are used as non-ionic (neutral) X-ray contrast agents in most cases [1]. Extracellular MRI Contrast Agents Based on Gadolinium....Pages 1-24 Structures of MRI Contrast Agents in Solution....Pages 25-60 Relaxivity of MRI Contrast Agents....Pages 61-101 Kinetic Stabilities of Gadolinium(III) Chelates Used as MRI Contrast Agents....Pages 103-122 New Classes of MRI Contrast Agents....Pages 123-164 Non-Gadolinium-Based MRI Contrast Agents....Pages 165-199 Blood-Pool MRI Contrast Agents: Properties and Characterization....Pages 201-235 Volume Editor, Werner Krause ; With Contributions By E. Brücher ... [et. Al.]. Includes Bibliographical References And Indexes. A summary of the development of extracellular MRI contrast agents during the last twenty years is given. The artificial element technetium was discovered by Perrier and Segre in 1937 [1].