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      Strain measurement on four-dimensional dynamic-ventilation CT: quantitative analysis of abnormal respiratory deformation of the lung in COPD

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          Abstract

          Purpose

          Strain measurement is frequently used to assess myocardial motion in cardiac imaging. This study aimed to apply strain measurement to pulmonary motion observed by four-dimensional dynamic-ventilation computed tomography (CT) and to clarify motion abnormality in COPD.

          Materials and methods

          Thirty-two smokers, including ten with COPD, underwent dynamic-ventilation CT during spontaneous breathing. CT data were continuously reconstructed every 0.5 seconds. In the series of images obtained by dynamic-ventilation CT, five expiratory frames were identified starting from the peak inspiratory frame (first expiratory frame) and ending with the fifth expiratory frame. Strain measurement of the scanned lung was performed using research software that was originally developed for cardiac strain measurement and modified for assessing deformation of the lung. The measured strain values were divided by the change in mean lung density to adjust for the degree of expiration. Spearman’s rank correlation analysis was used to evaluate associations between the adjusted strain measurements and various spirometric values.

          Results

          The adjusted strain measurement was negatively correlated with FEV 1/FVC (ρ=−0.52, P<0.01), maximum mid-expiratory flow (ρ=−0.59, P<0.001), and peak expiratory flow (ρ=−0.48, P<0.01), suggesting that abnormal deformation of lung motion is related to various patterns of expiratory airflow limitation.

          Conclusion

          Abnormal deformation of lung motion exists in COPD patients and can be quantitatively assessed by strain measurement using dynamic-ventilation CT. This technique can be expanded to dynamic-ventilation CT in patients with various lung and airway diseases that cause abnormal pulmonary motion.

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          Most cited references 27

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          Current and evolving echocardiographic techniques for the quantitative evaluation of cardiac mechanics: ASE/EAE consensus statement on methodology and indications endorsed by the Japanese Society of Echocardiography.

          Echocardiographic imaging is ideally suited for the evaluation of cardiac mechanics because of its intrinsically dynamic nature. Because for decades, echocardiography has been the only imaging modality that allows dynamic imaging of the heart, it is only natural that new, increasingly automated techniques for sophisticated analysis of cardiac mechanics have been driven by researchers and manufacturers of ultrasound imaging equipment.Several such technique shave emerged over the past decades to address the issue of reader's experience and inter measurement variability in interpretation.Some were widely embraced by echocardiographers around the world and became part of the clinical routine,whereas others remained limited to research and exploration of new clinical applications.Two such techniques have dominated the research arena of echocardiography: (1) Doppler based tissue velocity measurements,frequently referred to as tissue Doppler or myocardial Doppler, and (2) speckle tracking on the basis of displacement measurements.Both types of measurements lend themselves to the derivation of multiple parameters of myocardial function. The goal of this document is to focus on the currently available techniques that allow quantitative assessment of myocardial function via image-based analysis of local myocardial dynamics, including Doppler tissue imaging and speckle-tracking echocardiography, as well as integrated backscatter analysis. This document describes the current and potential clinical applications of these techniques and their strengths and weaknesses,briefly surveys a selection of the relevant published literature while highlighting normal and abnormal findings in the context of different cardiovascular pathologies, and summarizes the unresolved issues, future research priorities, and recommended indications for clinical use.
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            Quantitative assessment of intrinsic regional myocardial deformation by Doppler strain rate echocardiography in humans: validation against three-dimensional tagged magnetic resonance imaging.

            Tissue Doppler echocardiography-derived strain rate and strain measurements (SDE) are new quantitative indices of intrinsic cardiac deformation. The aim of this study was to validate and compare these new indices of regional cardiac function to measurements of 3-dimensional myocardial strain by tagged MRI. The study population included 33 healthy volunteers, 17 patients with acute myocardial infarction, and 8 patients with suspected coronary artery disease who were studied during dobutamine stress echocardiography. Peak systolic myocardial velocities were measured by tissue Doppler echocardiography, peak systolic strain rates and strains by SDE, and strains by tagged MRI. In healthy individuals, longitudinal myocardial Doppler velocities decreased progressively from base to apex, whereas myocardial strain rates and strains were uniform in all segments. In patients with acute infarction, abnormal strains clearly identified dysfunctional areas. In infarcted regions, SDE showed 1.5+/-4.3% longitudinal stretching compared with -15.0+/-3.9% shortening in remote myocardium (P<0.001), and radial measurements showed -6.9+/-4.1% thinning and 14.3+/-5.0% thickening (P<0.001), respectively. During dobutamine infusion, longitudinal strains by SDE increased significantly from -13.5% to -23.8% (P<0.01) and radial strains increased from 13.1+/-3.1% to 29.3+/-11.5% (P<0.01). Comparisons between myocardial strains by SDE and tagged MRI in healthy individuals (n=11), in infarct patients (n=17), and during stress echo (n=4) showed excellent correlations (r=0.89 and r=0.96 for longitudinal and radial strains, respectively, P< 0.001). The present study demonstrates the ability of Doppler echocardiography to measure myocardial strains in a clinical setting. Myocardial strains by Doppler may represent a new powerful method for quantifying left ventricular function noninvasively in humans.
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              Mechanical dispersion assessed by myocardial strain in patients after myocardial infarction for risk prediction of ventricular arrhythmia.

              The aim of this study was to investigate whether myocardial strain echocardiography can predict ventricular arrhythmias in patients after myocardial infarction (MI). Left ventricular (LV) ejection fraction (EF) is insufficient for selecting patients for implantable cardioverter-defibrillator (ICD) therapy after MI. Electrical dispersion in infarcted myocardium facilitates malignant arrhythmia. Myocardial strain by echocardiography can quantify detailed regional and global myocardial function and timing. We hypothesized that electrical abnormalities in patients after MI will lead to LV mechanical dispersion, which can be measured as regional heterogeneity of contraction by myocardial strain. We prospectively included 85 post-MI patients, 44 meeting primary and 41 meeting secondary ICD prevention criteria. After 2.3 years (range 0.6 to 5.5 years) of follow-up, 47 patients had no and 38 patients had 1 or more recorded arrhythmias requiring appropriate ICD therapy. Longitudinal strain was measured by speckle tracking echocardiography. The SD of time to maximum myocardial shortening in a 16-segment LV model was calculated as a parameter of mechanical dispersion. Global strain was calculated as average strain in a 16-segment LV model. The EF did not differ between ICD patients with and without arrhythmias occurring during follow-up (34 +/- 11% vs. 35 +/- 9%, p = 0.70). Mechanical dispersion was greater in ICD patients with recorded ventricular arrhythmias compared with those without (85 +/- 29 ms vs. 56 +/- 13 ms, p 35%, global strain showed better LV function in those without recorded arrhythmias (-14.0% +/- 4.0% vs. -12.0 +/- 3.0%, p = 0.05), whereas the EF did not differ (44 +/- 8% vs. 41 +/- 5%, p = 0.23). Mechanical dispersion was more pronounced in post-MI patients with recurrent arrhythmias. Global strain was a marker of arrhythmias in post-MI patients with relatively preserved ventricular function. These novel parameters assessed by myocardial strain may add important information about susceptibility for ventricular arrhythmias after MI. Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
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                Author and article information

                Journal
                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of COPD
                International Journal of Chronic Obstructive Pulmonary Disease
                Dove Medical Press
                1176-9106
                1178-2005
                2019
                18 December 2018
                : 14
                : 65-72
                Affiliations
                [1 ]Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara, Okinawa, Japan, clatsune@ 123456yahoo.co.jp
                [2 ]Department of Radiology, China-Japan Friendship Hospital, Beijing, Republic of China
                [3 ]Department of Radiology, Ohara General Hospital, Fukushima-City, Fukushima, Japan
                [4 ]Department of Radiology, Shiga University of Medical Science, Otsu, Shiga, Japan
                [5 ]Department of Radiology, St Marianna University School of Medicine, Kawasaki, Kanagawa, Japan
                Author notes
                Correspondence: Tsuneo Yamashiro, Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan, Tel +81 98 895 1162, Fax +81 98 895 1420, Email clatsune@ 123456yahoo.co.jp
                Article
                copd-14-065
                10.2147/COPD.S183740
                6305131
                © 2019 Xu et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

                Categories
                Original Research

                Respiratory medicine

                emphysema, copd, strain measurement, dynamic-ventilation ct, ct, computed tomography

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