Diffusion lung imaging with hyperpolarized gas MRI

Dmitriy A. Yablonskiy, Alexander L. Sukstanskii, James D. Quirk
<span title="2015-12-16">2015</span> <i title="Wiley"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/rr3xugvwirasdcilw2b3upxqpi" style="color: black;">NMR in Biomedicine</a> </i> &nbsp;
Lung imaging using conventional 1 H MRI presents great challenges due to low density of lung tissue, lung motion and very fast lung tissue transverse relaxation (typical T2* is about 1-2 ms). MRI with hyperpolarized gases ( 3 He and 129 Xe) provides a valuable alternative due to a very strong signal originated from inhaled gas residing in the lung airspaces and relatively slow gas T2* relaxation (typical T2* is about 20-30 ms). Though in vivo human experiments should be done very fast -usually
more &raquo; ... uring a single breath-hold. In this review we describe the recent developments in diffusion lung MRI with hyperpolarized gases. We show that a combination of modeling results of gas diffusion in lung airspaces and diffusion measurements with variable diffusion-sensitizing gradients allows extracting quantitative information on the lung microstructure at the alveolar level. This approach, called in vivo lung morphometry, allows from a less than 15-second MRI scan, providing quantitative values and spatial distributions of the same physiological parameters as are measured by means of the "standard" invasive stereology (mean linear intercept, surface-tovolume ratio, density of alveoli, etc.). Besides, the approach makes it possible to evaluate some advanced Weibel parameters characterizing lung microstructure -average radii of alveolar sacs and ducts, as well as the depth of their alveolar sleeves. Such measurements, providing in vivo information on the integrity of pulmonary acinar airways and their changes in different diseases, are of great importance and interest to a broad range of physiologists and clinicians. We also discuss a new type of experiments that are based on the in vivo lung morphometry technique combined with quantitative CT measurements as well as with the Gradient Echo MRI measurements of hyperpolarized gas transverse relaxation in the lung airspaces. Such experiments provide additional information on the blood vessel volume fraction, specific gas volume, the length of acinar airways, and allows evaluation of lung parenchymal and non-parenchymal tissue.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1002/nbm.3448">doi:10.1002/nbm.3448</a> <a target="_blank" rel="external noopener" href="https://www.ncbi.nlm.nih.gov/pubmed/26676342">pmid:26676342</a> <a target="_blank" rel="external noopener" href="https://pubmed.ncbi.nlm.nih.gov/PMC4911335/">pmcid:PMC4911335</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/zozuygsvt5b63kd3jzy43v4nua">fatcat:zozuygsvt5b63kd3jzy43v4nua</a> </span>
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