In a recently published paper by Parra-Robles and Wild, the authors challenge the in vivo lung morphometry technique (based on hyperpolarized gas diffusion MRI) developed by our Washington University research group. In this Commentary we demonstrate that the main conclusion of Parra-Robles and Wild, that our MRI-based lung morphometry technique "produces inaccurate estimates of the airway dimensions", does not have any scientific basis and is not in agreement with the considerable body of peer-reviewed scientific reports as well as with Parra-Robles and Wild's own data. On the contrary, our technique has a strong theoretical background, is validated, and provides accurate 3D tomographic information on lung microstructural parameters previously available only from invasive biopsy specimens. This technique has already produced a number of results related to lung morphology and function that were not previously available. In our Commentary we also discuss a number of other incorrect statements in and shortcomings of Parra-Robles and Wild's paper.
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http://dx.doi.org/10.1016/j.jmr.2013.09.019 | DOI Listing |
Magn Reson Med
July 2021
POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.
Purpose: This work assesses the accuracy of the stretched exponential (SEM) and cylinder models of lung microstructural length scales that can be derived from hyperpolarized gas DWI. This was achieved by simulating He and Xe DWI signals within two micro-CT-derived realistic acinar airspace meshes that represent healthy and idiopathic pulmonary fibrosis lungs.
Methods: The healthy and idiopathic pulmonary fibrosis acinar airway meshes were derived from segmentations of 3D micro-CT images of excised human lungs and meshed for finite element simulations of the Bloch-Torrey equations.
Radiology
September 2017
From the Unit of Academic Radiology, Department of Infection, Immunity and Cardiovascular Disease, C Floor, Royal Hallamshire Hospital, University of Sheffield, Glossop Rd, Sheffield S10 2JF, England (F.C.H., H.M., G.J.C., J.P., J.M.W.); Novartis, Basel, Switzerland (R.K.); Department of Respiratory Medicine, Glenfield Hospital, Leicester, England (S.S., C.E.B.); Insigneo Institute of In-Silico Medicine, University of Sheffield, Sheffield, England (J.M.W.).
Purpose To assess the magnitude of regional response to respiratory therapeutic agents in the lungs by using treatment response mapping (TRM) with hyperpolarized gas magnetic resonance (MR) imaging. TRM was used to quantify regional physiologic response in adults with asthma who underwent a bronchodilator challenge. Materials and Methods This study was approved by the national research ethics committee and was performed with informed consent.
View Article and Find Full Text PDFThorax
August 2017
POLARIS, Academic Radiology, University of Sheffield, Sheffield, UK.
Hyperpolarised He ventilation-MRI, anatomical lung MRI, lung clearance index (LCI), low-dose CT and spirometry were performed on 19 children (6-16 years) with clinically stable mild cystic fibrosis (CF) (FEV>-1.96), and 10 controls. All controls had normal spirometry, MRI and LCI.
View Article and Find Full Text PDFJ Magn Reson
October 2016
POLARIS, Academic Unit of Radiology, University of Sheffield, C Floor, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, United Kingdom. Electronic address:
Existing models of (129)Xe diffusive exchange for lung microstructural modeling with time-resolved MR spectroscopy data have considered analytical solutions to one-dimensional, homogeneous models of the lungs with specific assumptions about the alveolar geometry. In order to establish a model system for simulating the effects of physiologically-realistic changes in physical and microstructural parameters on (129)Xe exchange NMR, we have developed a 3D alveolar capillary model for finite element analysis. To account for the heterogeneity of the alveolar geometry across the lungs, we have derived realistic geometries for finite element analysis based on 2D histological samples and 3D micro-CT image volumes obtained from ex vivo biopsies of lung tissue from normal subjects and patients with interstitial lung disease.
View Article and Find Full Text PDFMagn Reson Med
May 2017
POLARIS, Academic Unit of Radiology, University of Sheffield, United Kingdom.
Purpose: To demonstrate three-dimensional (3D) multiple b-value diffusion-weighted (DW) MRI of hyperpolarized He gas for whole lung morphometry with compressed sensing (CS).
Methods: A fully-sampled, two b-value, 3D hyperpolarized He DW-MRI dataset was acquired from the lungs of a healthy volunteer and retrospectively undersampled in the k and k phase-encoding directions for CS simulations. Optimal k-space undersampling patterns were determined by minimizing the mean absolute error between reconstructed and fully-sampled He apparent diffusion coefficient (ADC) maps.
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