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Abstract #1906

Macrocyclic Ferrocenyl DTPA-Bis (Amide) for Gd-Chelate as a New Class of MRI Blood Pool Contrast Agents

Hee-Kyung Kim1, Nasiruzzaman Sk Md2, Ji-Ae Park3, Seung-Tae Woo4, Tae-Jung Kim5, Yongmin Chang1,6

1Department of Medical & Biological Engineering, Kyungpook National University, Daegu, Korea, Republic of; 2Advanced Research Institute for Recovery of Human Sensitibiliy, Daegu, Korea, Republic of; 3Korea Institute of Radiological & Medical Science, Seoul, Korea, Republic of; 4Bayer Schering Pharma Korea, Seoul, Korea, Republic of; 5Department of Applied Chemistry, Kyungpook National University, Daegu, Korea, Republic of; 6Department of Diagnostic Radiology and Molecular Medicine, Kyungpook National university, Daegu, Korea, Republic of

We report the synthesis of 1,1-ferrocendiylamines (L) and their Gd(III) complexes of the type [Gd(L)(H2O)], referred to as Ferromides, as a new family of BPCAs. Also reported is the investigation of their thermodynamic and magnetic resonance properties along with in vitro and in vivo MR studies. They all exhibit greater thermodynamic stability (ie., logKsel) than their acyclic and cyclic analogues such as DTPA-BMA, DTPA, and DOTA and compare favorably to MS-325, a well-known BPCA. The R1 relaxivities of Ferromides are quite high as compared with other MRI CAs currently in use. In the case of Ferromide-1, for instance, the R1 relaxivity is 7.5 mM1sec1, which is twice as high as that of structurally related Dotarem (R1=3.6 mM1sec1). The R1 relaxivity is further increased in an aqueous saline solution of HSA (4.5% w/v) to be compared quite favorably to that of MS-325, and most strikingly, the increase is observed even in the absence of the electrostatic phosphate-HSA interaction. The in vivo MR images of mice obtained with Ferromide-1 show the contrast enhancement not only in heart and bladder but also in abdominal aorta, clearly demonstrating the blood-pool effect.