Vertical gradients in regional alveolar oxygen tension in supine human lung imaged by hyperpolarized 3He MRI. (December 2014)

• Record Type: Journal Article
• Authors: Hamedani, Hooman; Shaghaghi, Hoora; Kadlecek, Stephen J.; Xin, Yi; Han, Biao; Siddiqui, Sarmad; Rajaei, Jennia; Ishii, Masaru; Rossman, Milton; Rizi, Rahim R.; Rizi, Rahim R.
• Is Part Of: NMR in biomedicine. Volume 27:Number 12(2014:Dec.)
• Page Start: 1439
• Page End: 1450
• Publication Date: 2014-12
• Subjects: Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.3227
• Languages: English
• ISSNs: 0952-3480

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The purpose of this study was to evaluate whether regional alveolar oxygen tension (<italic>P</italic><sub>A</sub>O<sub>2</sub>) vertical gradients imaged with hyperpolarized <sup>3</sup>He can identify smoking‐induced pulmonary alterations. These gradients are compared with common clinical measurements including pulmonary function tests (PFTs), the six minute walk test, and the St. George's Respiratory Questionnaire.</p> <p>8 healthy non‐smokers, 12 asymptomatic smokers, and 7 symptomatic subjects with chronic obstructive pulmonary disease (COPD) underwent two sets of back‐to‐back <italic>P</italic><sub>A</sub>O<sub>2</sub> imaging acquisitions in the supine position in two opposite directions (top to bottom and bottom to top), followed by clinically standard pulmonary tests. The whole‐lung mean, standard deviation (D<italic>P</italic><sub>A</sub>O<sub>2</sub>) and vertical gradients of <italic>P</italic><sub>A</sub>O<sub>2</sub> along the slices were extracted, and the results were compared with clinically derived metrics. Statistical tests were performed to analyze the differences between cohorts.</p> <p>The anterior–posterior vertical gradients and D<italic>P</italic><sub>A</sub>O<sub>2</sub> effectively differentiated all three cohorts (<italic>p</italic> <0.05). The average vertical gradient <italic>P</italic><sub>A</sub>O<sub>2</sub> in healthy subjects was −1.03 ± 0.51 Torr/cm toward lower values in the posterior/dependent regions. The directional gradient was absent in smokers (0.36 ± 1.22 Torr/cm) and was in the opposite direction in COPD subjects (2.18 ± 1.54 Torr/cm). The vertical gradients correlated with smoking history (<italic>p</italic> =0.004); body mass index (<italic>p</italic> =0.037), PFT metrics (forced expiratory volume in 1 s, <italic>p</italic> =0.025; residual volume/total lung capacity percent predicted, <italic>p</italic> =0.033) and with distance walked in 6 min (<italic>p</italic> =0.009).</p> <p>Regional <italic>P</italic><sub>A</sub>O<sub>2</sub> data indicate that cigarette smoke induces physiological alterations that are not being detected by the most widely used physiological tests. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>