FIGURE 3.

Temporal changes in the spectroscopic parameters of the ¹²⁹Xe gas, barrier, and RBC resonances in a representative healthy subject (Subject 6) during inhalation, breath-hold (gray bar), and exhalation. All amplitudes were normalized to the maximum ¹²⁹Xe barrier signal. The barrier resonance contains both a Lorentzian FWHM (solid light green line) and a Gaussian FWHM (dark green dotted line). The arrows highlight changes in the spectroscopic chemical shift, linewidth, and phase that occur upon exhalation. The line above the RBC amplitude highlights the cardiogenic oscillations, occurring at a frequency of 58 cycles per minute in this subject