Quantitative assessment of regional lung ventilation in emphysematous mice using hyperpolarized 129 Xe MRI with a continuous flow hyperpolarizing system.

Background: Lung ventilation function in small animals can be assessed by using hyperpolarized gas MRI. For these experiments a free breathing protocol is generally preferred to mechanical ventilation as mechanical ventilation can often lead to ventilation lung injury, while the need to maintain a gas reservoir may lead to a partial reduction of the polarization.
Purpose: To evaluate regional lung ventilation of mice by a simple but fast method under free breathing and give evidence for effectiveness with an elastase instilled emphysematous mice.
Animal Model: Emphysematous mice.
Materials and Methods: A Look-Locker based saturation recovery sequence was developed for continuous flow hyperpolarized (CF-HP) ¹²⁹ Xe gas experiments, and the apparent gas-exchange rate, k', was measured by the analysis of the saturation recovery curve.
Results: In mice with elastase-induced mild emphysema, reductions of 15-30% in k' values were observed as the results of lesion-induced changes in the lung.
Data Conclusion: The proposed method was applied to an emphysematous model mice and ventilation dysfunctions have been approved as a definite decrease in k' values, supporting the usefulness for a non-invasive assessment of the lung functions in preclinical study by the CF-HP ¹²⁹ Xe experiments.
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