Purpose:
To evaluate the dependency of the
129
Xe-red blood
cell (RBC) chemical shift on blood oxygenation, and to use
this relation for noninvasive measurement of pulmonary blood
oxygenation in vivo with hyperpolarized
129
Xe NMR.
Methods:
Hyperpolarized
129
Xe was equilibrated with blood
samples of varying oxygenation in vitro, and NMR was performed
at 1.5 T and 3 T. Dynamic in vivo NMR during breath hold apnea
was performed at 3 T on two healthy volunteers following inhala-
tion of hyperpolarized
129
Xe.
Results:
The
129
Xe chemical shift in RBCs was found to increase
nonlinearly with blood oxygenation at 1.5 T and 3 T. During breath
hold apnea, the
129
Xe chemical shift in RBCs exhibited a periodic
time modulation and showed a net decrease in chemical shift of
~
1 ppm over a 35 s breath hold, corresponding to a decrease of
7–10 % in RBC oxygenation. The
129
Xe-RBC signal amplitude
showed a modulation with the same frequency as the
129
Xe-RBC
chemical shift.
Conclusion:
The feasibility of using the
129
Xe-RBC chemical shift
to measure pulmonary blood oxygenation in vivo has been dem-
onstrated. Correlation between
129
Xe-RBC signal and
129
Xe-RBC
chemical shift modulations in the lung warrants further investiga-
tion, with the aim to better quantify temporal blood oxygenation
changes in the cardiopulmonary vascular circuit
