Comparison of hyperpolarized (3)He and (129)Xe MRI for the measurement of absolute ventilated lung volume in rats.

PURPOSE

MRI using hyperpolarized noble gases, (3)He and (129)Xe, provides noninvasive assessments of lung structure and function. Previous work demonstrated that absolute ventilated lung volumes (aVLV) measured in rats using hyperpolarized (3)He agree well with micro-CT.

METHODS

In this work, aVLV measurements were performed in rats using hyperpolarized (129)Xe MRI and compared with hyperpolarized (3)He measurements of aVLV under matched ventilation conditions. Whole-lung compliance was also determined. Partial volume, apparent diffusion coefficient, and effective transverse relaxation time corrections were applied during postprocessing to reduce bias between methods.

RESULTS

Mean apparent diffusion coefficient of the trachea was 0.83 ± 0.09 cm(2)/s and 0.067 ± 0.011 cm(2)/s for (3)He and (129)Xe, respectively. Mean apparent diffusion coefficient of parenchyma was 0.21 ± 0.07 cm(2)/s and 0.027 ± 0.008 cm(2)/s for (3)He and (129)Xe, respectively. Mean transverse relaxation time values were 1.57 ± 0.25 ms and 2.80 ± 0.25 ms for (3)He and (129)Xe, respectively, in a model trachea and 3.18 ± 1.00 ms and 4.88 ± 0.60 ms for (3)He and (129)Xe, respectively, for lung parenchyma. Mean aVLV values were 7.07 ± 0.67 mL and 6.99 ± 1.00 mL at 14 cmH2O and 4.88 ± 0.71 mL and 5.36 ± 0.76 mL at 10 cmH2O obtained with (3)He and (129)Xe, respectively, demonstrating good agreement between (129)Xe and (3)He.

CONCLUSIONS

(129)Xe offers an important alternative to (3)He for hyperpolarized gas MRI of aVLV in rats.