Figure 14.

A HXe spectrum acquired in a healthy rat shows three distinct peaks, corresponding to gas in the alveoli/airways (set to 0 ppm), dissolved in tissue and blood plasma (197 ppm) and transiently bound to hemoglobin (~210.5 ppm). In vivo spectra in rats, humans, sheep and goats display distinct dissolved peaks that can be interrogated separately with an appropriate acquisition sequence, while those in pigs, rabbits and mice do not. Because the RF pulse was selective for dissolved components, the peak sizes greatly overrepresent the dissolved fraction.