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Vertical gradients in regional alveolar oxygen tension in supine human lung imaged by hyperpolarized 3 He MRI
Author(s) -
Hamedani Hooman,
Shaghaghi Hoora,
Kadlecek Stephen J.,
Xin Yi,
Han Biao,
Siddiqui Sarmad,
Rajaei Jennia,
Ishii Masaru,
Rossman Milton,
Rizi Rahim R.
Publication year - 2014
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3227
Subject(s) - supine position , copd , medicine , asymptomatic , lung volumes , nuclear medicine , pulmonary function testing , lung , respiratory system , cardiology
The purpose of this study was to evaluate whether regional alveolar oxygen tension ( P A O 2 ) vertical gradients imaged with hyperpolarized 3 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. 8 healthy non‐smokers, 12 asymptomatic smokers, and 7 symptomatic subjects with chronic obstructive pulmonary disease (COPD) underwent two sets of back‐to‐back P A O 2 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 P A O 2 ) and vertical gradients of P A O 2 along the slices were extracted, and the results were compared with clinically derived metrics. Statistical tests were performed to analyze the differences between cohorts. The anterior–posterior vertical gradients and D P A O 2 effectively differentiated all three cohorts ( p <0.05). The average vertical gradient P A O 2 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 ( p =0.004); body mass index ( p =0.037), PFT metrics (forced expiratory volume in 1 s, p =0.025; residual volume/total lung capacity percent predicted, p =0.033) and with distance walked in 6 min ( p =0.009). Regional P A O 2 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.