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Transverse relaxation rates of pulmonary dissolved-phase Hyperpolarized Xe-129 as a biomarker of lung injury in idiopathic pulmonary fibrosis
Journal article   Open access   Peer reviewed

Transverse relaxation rates of pulmonary dissolved-phase Hyperpolarized Xe-129 as a biomarker of lung injury in idiopathic pulmonary fibrosis

Jeff Kammerman, Andrew D. Hahn, Robert Cadman, Annelise Malkus, David Mummy and Sean B. Fain
Magnetic resonance in medicine, Vol.84(4), pp.1857-1867
10/01/2020
DOI: 10.1002/mrm.28246
PMCID: PMC7329592
PMID: 32162357
url
https://www.ncbi.nlm.nih.gov/pmc/articles/7329592View
Open Access

Abstract

Purpose: The MR properties (chemical shifts and R-2*decay rates) of dissolved-phase hyperpolarized (HP)Xe-129 are confounded by the large magnetic field inhomogeneity present in the lung. This work improves measurements of these properties using a model-based image reconstruction to characterize the R-2* decay rates of dissolved-phase HP Xe-129 in healthy subjects and patients with idiopathic pulmonary fibrosis (IPF). Methods: Whole-lung MRS and 3D radial MRI with four gradient echoes were performed after inhalation of HP Xe-129 in healthy subjects and patients with IPF. A model-based image reconstruction formulated as a regularized optimization problem was solved iteratively to measure regional signal intensity in the gas, barrier, and red blood cell (RBC) compartments, while simultaneously measuring their chemical shifts and R-2* decay rates. Results: The estimation of spectral properties reduced artifacts in images of HP Xe-129 in the gas, barrier, and RBC compartments and improved image SNR by over 20%. R-2*decay rates of the RBC and barrier compartments were lower in patients with IPF compared to healthy subjects (P < 0.001 and P= 0.005, respectively) and correlated to DLCO (R = 0.71 and 0.64, respectively). Chemical shift of the RBC component measured with whole-lung spectroscopy was significantly different between IPF and normal subjects (P = 0.022). Conclusion: Estimates for R-2* in both barrier and RBC dissolved-phase HP Xe-129 compartments using a regional signal model improved image quality for dissolved-phase images and provided additional biomarkers of lung injury in IPF.
Life Sciences & Biomedicine Radiology, Nuclear Medicine & Medical Imaging Science & Technology

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