Quantitative evaluation of lung injury caused by PM_2.5 using hyperpolarized gas magnetic resonance

Abstract

Purpose:To demonstrate the feasibility of 129 Xe MR in evaluating the pulmonary physiological changes caused by PM 2.5 in animal models. Methods: Six rats were treated with PM 2.5 solution (16.2 mg/kg) by intratracheal instillation twice a week for 4 weeks, and another six rats treated with normal saline served as the control cohort. Pulmonary function tests, hyperpolarized 129 Xe multi-b diffusion-weighted imaging, and chemical shift saturation recovery MR spectroscopy were performed on all rats, and the pulmonary structure and functional parameters were obtained from hyperpolarized 129 Xe MR data. Additionally, histological analysis was performed on all rats to evaluate alveolar septal thickness. Statistical analysis of all the obtained parameters was performed using unpaired 2-tailed t tests. Results: Compared with the control group, the measured exchange time constant increased from 11.74 ± 2.39 to 14.00 ± 2.84 ms (P < .05), and the septal wall thickness increased from 6.17 ± 0.48 to 6.74 ± 0.52 μm (P < .05) in the PM 2.5 cohort by 129 Xe MR spectroscopy, which correlated well with that obtained using quantitative histology (increased from 5.52 ± 0.32 to 6.20 ± 0.36 μm). Additionally, the mean TP/GAS ratio increased from 0.828 ± 0.115 to 1.019 ± 0.140 in the PM 2.5 cohort (P = .021). Conclusions: Hyperpolarized 129 Xe MR could quantify the changes in gas exchange physiology caused by PM 2.5 , indicating that the technique has the potential to be a useful tool for evaluation of pulmonary injury caused by air pollution in the future. K E Y W O R D Sair pollution, gas exchange, hyperpolarized 129 Xe, lung injury, PM 2.5 570 | ZHANG et Al.

Investigating biases in the measurement of apparent alveolar septal wall thickness with hyperpolarized 129Xe MRI

“…The DP imaging techniques currently in use can be divided into two general types: (1) static measurements of the regional xenon distribution within the lung parenchyma as dictated by the structure and physiology of the lung, 9‐19 and the MR acquisition parameters, in particular the flip angle and the TR 20‐22 ; and (2) dynamic measurements that capture the xenon gas uptake by the lung tissue and transport by the pulmonary circulation as a function of time 3,9,23‐30 . Both approaches have already been shown to be sensitive to various forms of lung disease 31‐42 . More recently, efforts have been made to combine these methods by adding 2D or 3D spatial information to dynamic gas uptake measurements at the expense of lengthened scan times 43,44 .…”

“…3,9,[23][24][25][26][27][28][29][30] Both approaches have already been shown to be sensitive to various forms of lung disease. [31][32][33][34][35][36][37][38][39][40][41][42] More recently, efforts have been made to combine these methods by adding 2D or 3D spatial information to dynamic gas uptake measurements at the expense of lengthened scan times. 43,44 Nevertheless, although xenon uptake MR techniques for quantifying lung function have been in use for over 20 years, little attention has been paid to the impact of the acquisition parameters on the metrics extracted.…”

In Vivo Nitroreductase Imaging via Fluorescence and Chemical Shift Dependent 19F NMR

“…In orthotopic lung cancer model mice, a 20 μL 10 mM contrast medium was injected into the lung area by drip irrigation [25] . After 2 hours, we can detect the existence of FCy7‐NO 2 both in the left lung and the right lung.…”

Measuring pulmonary gas exchange using compartment‐selective xenon‐polarization transfer contrast (XTC) MRI

“…Numerous hyperpolarized xenon‐129 (HXe) MRI approaches have emerged for assessing lung function, with applications in the diagnosis or characterization of various lung disorders, including chronic obstructive pulmonary disease (COPD), asthma, cystic fibrosis, and others 1‐12 . Importantly, this modality is capable of directly measuring pulmonary gas exchange by taking advantage of the chemical shifts xenon exhibits when moving from the alveolar air spaces (gas‐phase) into the parenchyma (dissolved‐phase) 13‐19 . However, imaging dissolved‐phase (DP) HXe remains challenging, as only approximately 2% of inhaled xenon dissolves into the lung parenchyma, 20,21 and the of the DP signal at 1.5T is only on the order of 1‐2 ms. As a result, DP imaging techniques based on xenon gas uptake, such as chemical shift imaging (CSI), 22 DP excitation imaging, 16,23 IDEAL 15 or Dixon‐type DP acquisitions, 13,24,25 are frequently limited by low spatial resolution or inefficient radial k‐space sampling schemes.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] Importantly, this modality is capable of directly measuring pulmonary gas exchange by taking advantage of the chemical shifts xenon exhibits when moving from the alveolar air spaces (gasphase) into the parenchyma (dissolved-phase). [13][14][15][16][17][18][19] However, imaging dissolved-phase (DP) HXe remains challenging, as only approximately 2% of inhaled xenon dissolves into the lung parenchyma, 20,21 and the T * 2 of the DP signal at 1.5T is only on the order of 1-2 ms. As a result, DP imaging techniques based on xenon gas uptake, such as chemical shift imaging (CSI), 22 DP excitation imaging, 16,23 IDEAL 15 or Dixon-type DP acquisitions, 13,24,25 are frequently limited by low spatial resolution or inefficient radial k-space sampling schemes. In addition, quantifying gas exchange measurements obtained with these methods is complicated by physiological gas transport processes via the pulmonary circulation, the impacts of which are inversely related to the size of the imaged subject or species.…”