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Contrast Agents in MRI What is MRI Magnetic Resonance Imaging Medical imaging technique Non-invasive Fast scan times Contrast resolution No ionizing radiation How does it work? A magnetic field to align the nuclear magnetization Generate a 2D image using the T1 relaxation time of proton in water in the body • T1 relaxation: • T1 measurement: Imaging Slice selection Two-Dimensional Fourier Transform (2DFT) technique K-space Slice selection kspace Imag e Contrast Agents Six clinically approved contrast agents used worldwide: Gd(DTPA)2- (Magnevist®) Gd(DOTA)- (Dotarem®) Gd(DTPA-BMA) (Omniscan®) Gd(HPDO3A) (Prohance®) mangafodipir trisodium (Telescan®) Ferumoxides (Resovist®, Cliavist ™) Why Gadolinium? paramagnetic unpaired electrons Slow rotational correlation time Enhance relaxation of water molecule But wait… As a free ion, Gd ion is highly toxic 0.2 mmol/kg in mice Disruption of Ca(II) signaling Form stable complexes that can accumulate within the body Nephrogenic systemic fibrosis Magnevist [Gd(DTPA)(H2O)]2- in 1988 How does it enhance contrast Relaxation enhancement of the water molecule Inner sphere relaxivity Outer sphere relaxivity Shortening of T1 gives brighter image where the contrast agent is taken up Reference Bottrill, M.; Kwok, L.; Long, N J Chem Soc Rev 2006, 35, 557–571 Caravan, P.; Ellison, J J.; McMurry, T J.; Lauffer, R B Chem Rev 1999, 99, 2293-2352 Gallagher,T A; Nemeth, A J; Bey, L H Am J Roen 2008 190 1396-1405 Woods, M.; Woessner, D E.; Sherry, A D Chem Soc Rev 2006, 35, 500–511 Lowe, M P.; Aust J Chem 2002 55 551-556 Derome A E “Modern NMR Techniques for Chemistry Research”; Pergamon Press Oxford 1987 ...What is MRI Magnetic Resonance Imaging Medical imaging technique Non-invasive Fast scan times Contrast resolution No ionizing radiation How does it work? ... Fourier Transform (2DFT) technique K-space Slice selection kspace Imag e Contrast Agents Six clinically approved contrast agents used worldwide: Gd(DTPA)2- (Magnevist®) Gd(DOTA)- (Dotarem®)... the nuclear magnetization Generate a 2D image using the T1 relaxation time of proton in water in the body • T1 relaxation: • T1 measurement: Imaging Slice selection Two-Dimensional Fourier