As discussed in the A Word About . . . NMR in Biology and Medicine on page

Question:

As discussed in the "A Word About . . . NMR in Biology and Medicine" on page 368, MRI typically uses 1H NMR spectra of water in various tissues. What is the disadvantage of using 13C NMR spectra? Suggest a method that could be used with MRI to enhance the signal strength (actually the signal-to-noise ratio) for a nucleus besides 1H.