HYPERPOLARIZED HE-3 NMR LINESHAPE MEASUREMENTS IN THE LIVE GUINEA-PIGLUNG

Spatially localized lineshapes of hyperpolarized (HP) He-3 in guinea p ig lungs have been measured in vivo. Three different axial slice locat ions, each containing different compositions of airway sizes and orien tations, were studied, Gas peaks from major bronchi (2 ppm) and alveol i (-2 ppm) were distinguished. The gas phase spectra show structural f eatures that are a result of frequency shifts caused by bulk magnetic susceptibility. For a given slice, the spectral lineshapes reflect the airway composition within the slice location, according to theory. Th e peak assignments given here also agree with previous studies done by Wagshul et al, with HP Xe-129. At each of the slice locations, data w ere acquired during two phases of the breathing cycle, resulting in a relative frequency shift of similar to 0.3 ppm in the superior slices, Spectra obtained over a number of breaths show the dynamics of the ga s buildup in the lung and provide further evidence supporting the peak assignments.