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Unformatted text preview: 3) In an MRI experiment contrast agents are used to help resolve spatially distinct elements by selectively shortening T1 or T2 spin relaxation times for those elements. Images are usually displayed with regions giving the most signal as light areas and those giving the least signal as dark areas. Suppose we use an iron oxide nanoparticle as a contrast agent. Would you uses a T2 enhanced or T1 enhanced sequence to acquire data? Would the areas affected by the nanoparticle appear as dark or light areas? 4) Estimate the rates of chemical exchange for the following examples: a) The NMR spectrum of N,N-dimethylnitrosamine shows distinct cis and trans methyl lines with width at half height = 1 Hz and a separation of 100 Hz. The inherent resolution due to homogeneity is 0.5 Hz. b) The same molecule in the same spectrometer shows a single line of width 5 Hz....
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- Fall '11