Studies On The New MRI Contrast Agents Of Diethylenetriaminepentaacetic Acid Derivatives

Studies on the new MRI contrast agents of DiethylenetriaminepentaaceticAcid DerivativesMagnetic resonance imaging (MRI) is a non-invasive and efficient imaging technique of in vivo tissue characterization which utilizes image contrast between normal and diseased tissue derived from differences in 'H nuclear spin relaxation rates. Though differentiation of untreated tissue is possible, the image contrast is often insufficient for diagnostic purposes. Nowadays, around 30% of all MRI investigations use contrast agents, which are designed for administration to patients in order to enhance the contrast between normal and diseased tissue or to indicate organ function or blood flow. Some paramagnetic complexes which were routinely used as contrast agents in human are non-specific. Over the past two decades, in order to achieve more direct targeting of chelates, many agents were used to modify DTPA and DOTA (DTPA is diethylenetriaminepentaacetic acid, DOTA is 1,4,7,10-tetraazacyclodo-decane-N,N',N",N'"-tetraacetic acid). In this paper, we use dihydropyridine and 7-amino-cephalosporanic acid modify DTPA, and attempt to obtain tissue-specific contrast agents with high relaxivities.1. Four novel ligands of DTPA-dihydropyridine derivatives have been synthesized by reaction of DTPA-dianhydride with 4-aniline-l,4-dihydropyridines. Their complexes of gadolinium, manganese and iron were prepared. Spin-lattice relaxivities(T1) have been investigated. The results showed that all the complexes have relaxation effects on the protons in surrounding water molecules. The Gd(III) complexes have higher relaxivities than those of Fe(III) and Mn(II) complexes and possess the precondition to be contrast agents for magnetic resonance imaging.2. The sprin-iattice relaxivity(T1) of a Gd-DTPA-dihydropyridine complex in aqueous and in bovine serum albumin(BSA) solution have been investigated. The results indicated that Gd-DTPA-dihydropyridine can integrate non-covalently with BSA. Two Gd-DTPA-dihydropyridine integrate one BSA is the possible form.3. Use 7-amino cephalosporanic acid (7-ACA)modify DTPA, Its complex ofgadolinium was prepared. Spin-lattice relaxivities(T1) have been investigated.