Chest Imaging of COPD

FOR RELATED ARTICLE, SEE PAGE 69Innumerable articles have been written and many millions of dollars have been invested in efforts to understand COPD. Yet, despite decades of research, there is still a paucity of evidence-based therapies that have a measurable effect on disease trajectory for patients with COPD. Perhaps this is because, although COPD is a complex pulmonary condition, it also impacts the heart and a multitude of extrathoracic organs including skeletal muscle, bone, brain, and the vasculature.1Divo M. Cote C. de Torres J.P. et al.BODE Collaborative GroupComorbidities and risk of mortality in patients with chronic obstructive pulmonary disease.Am J Respir Crit Care Med. 2012; 186: 155-161Crossref PubMed Scopus (817) Google Scholar FOR RELATED ARTICLE, SEE PAGE 69 In response to these challenges, over the past 4 decades the medical imaging research community has endeavored to address some of the knowledge and care gaps by developing new image acquisition and analysis algorithms to detect, quantify, and monitor these abnormalities. These approaches began with straightforward measures of lung tissue density and have evolved into complex algorithms leveraging the most advanced machine learning and deep learning tools. Despite this vast, ongoing effort, it should be noted that for COPD, there are no novel equivalents for the immune-biologic therapy that has become foundational for severe asthma.2Brusselle G.G. Koppelman G.H. Biologic therapies for severe asthma.N Engl J Med. 2022; 386: 157-171Crossref PubMed Scopus (149) Google Scholar In addition, there are no subclinical markers that parallel cholesterol level or even BP for heart disease, which can be used by primary care providers and cardiologists to intercept and prevent cardiovascular disease. Smoking cessation, oxygen supplementation, and lung volume reduction surgery, in select people, still prove to be the most impactful treatments, but typically these are implemented well after COPD has advanced to symptomatic illness.3Nocturnal Oxygen Therapy Trial GroupContinuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease: a clinical trial.Ann Intern Med. 1980; 93: 391-398Crossref PubMed Scopus (2144) Google Scholar, 4Medical Research Council Working PartyLong term domiciliary oxygen therapy in chronic hypoxic cor pulmonale complicating chronic bronchitis and emphysema: report of the Medical Research Council Working Party.Lancet. 1981; 1: 681-686PubMed Google Scholar, 5Fishman A. Martinez F. Naunheim K. et al.A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema.N Engl J Med. 2003; 348: 2059-2073Crossref PubMed Scopus (1697) Google Scholar, 6Anthonisen N.R. Skeans M.A. Wise R.A. Manfreda J. Kanner R.E. Connett J.E. Lung Health Study Research GroupThe effects of a smoking cessation intervention on 14.5-year mortality: a randomized clinical trial.Ann Intern Med. 2005; 142: 233-239Crossref PubMed Scopus (1072) Google Scholar Although the current suite of COPD interventional tools heralds important advancements, most of these “breakthroughs” were made 20 to 30 years ago. More recently, there have been meaningful but more incremental advances, such as bronchoscopic approaches to lung volume reduction for severe emphysema and oral therapies that help reduce exacerbations in patients with COPD who are prone to frequent acute worsening.7Criner G.J. Sue R. Wright S. et al.LIBERATE Study GroupA multicenter randomized controlled trial of Zephyr endobronchial valve treatment in heterogeneous emphysema (LIBERATE).Am J Respir Crit Care Med. 2018; 198: 1151-1164Crossref PubMed Scopus (194) Google Scholar, 8Albert R.K. Connett J. Bailey W.C. et al.COPD Clinical Research Network. Azithromycin for prevention of exacerbations of COPD.N Engl J Med. 2011; 365: 689-698Crossref PubMed Scopus (959) Google Scholar, 9Martinez F.J. Calverley P.M. Goehring U.M. Brose M. Fabbri L.M. Rabe K.F. Effect of roflumilast on exacerbations in patients with severe chronic obstructive pulmonary disease uncontrolled by combination therapy (REACT): a multicentre randomised controlled trial.Lancet. 2015; 385: 857-866Abstract Full Text Full Text PDF PubMed Scopus (283) Google Scholar Although COPD has certainly been challenging to treat, we also recognize that novel COPD imaging approaches may play a role in guiding therapy and have not yet been used to advance patient care and develop novel treatments. We think that a new approach, which we now term “Stop, Look, and Listen,” can bring us more meaningful imaging-based and patient-centered COPD interventions and advances. First, we think it is important to “Stop” to consider how each novel imaging approach also advances patient care. Second, we suggest that COPD imaging scientists “Look” to our colleagues in patient-facing roles and ask for input in framing a deeper understanding of the care gap for patients with COPD and what is needed from imaging science. Finally, we think it is important to “Listen” to what we can glean from frontline COPD clinicians and patients themselves. Taken together, “Stop, Look, and Listen” is an approach we think will help create a new dialogue between COPD imaging and COPD clinical sciences, which can orient the imaging research field toward even greater patient-centered advances. In this issue of CHEST, we hope to start the “Stop, Look, and Listen” process by introducing a new CHEST review series that is focused on Imaging COPD. In two review articles and a How I Do It contribution, CHEST provides practical, state-of-the-art summaries and discusses what imaging has provided, and may in the future provide, for patients with COPD and their care teams. In the first review article, entitled “Lung Imaging in COPD: Part 1: Clinical Utility,” Dr Raoof and colleagues10Raoof S. Shah M. Make B. et al.Lung imaging in COPD: Part 1: clinical utility.Chest. 2023; 164: 69-84Abstract Full Text Full Text PDF Scopus (1) Google Scholar summarize and illustrate the evolution of COPD imaging over the last 50 years. The next review article, entitled “Lung Imaging in COPD: Part 2: Emerging Concepts,” Dr Raoof and colleagues11Raoof S, Shah M, Braman S, et al. Lung imaging in COPD: Part 2: emerging concepts [published online ahead of print March 11, 2023]. Chest. https://doi.org/10.1016/j.chest.2023.02.049.Google Scholar introduce promising concepts and applications including COPD subtyping, biomarker development, prognostication, and disease monitoring. These review articles, for practical reasons, mainly summarize chest radiography, CT scan imaging developments, and biomarkers and do not provide expansive summaries about the potential roles of MRI and PET for imaging COPD. The focus here on practical and nearly universal CT scan imaging tools is not a judgment on the relative merit or the contributions of other methods to our understanding of COPD. A number of MRI and PET technologies certainly provide highly advanced noninvasive assessments of subvoxel microscopic and in vivo structure and function. These may be used in the future for monitoring the effect of treatments and for drug development. Last, the How I Do It contribution, entitled “Quantitative CT Airway Imaging for Diagnosis and Management of Lung Disease,” was authored by Drs Kirby and Smith,12Kirby M, Smith BM. Quantitative CT airway imaging for diagnosis and management of lung disease [published online ahead of print March 3, 2023]. Chest. https://doi.org/10.1016/j.chest.2023.02.044.Google Scholar two experts in quantitative imaging in COPD, one of whom treats patients with COPD. Their review summarizes in practical terms how CT scan imaging–based airway measurements are currently made, with the view that these research tools may soon be translated into clinical care. Together, these three review articles, coauthored by imaging experts, provide a thoughtful summary of the vast knowledge we have gained and the immense potential of the field. To make the point bluntly, while COPD imaging researchers continue to exploit computational power by developing advanced analytic tools in the name of revolutionizing therapeutic investigation, many of those delivering patient care are without direct access to a chest radiologist. Moreover, ever more elegant algorithms are quite sensitive to heterogeneities in image acquisition and reconstruction, and this has focused research on highly curated research-grade data. The resulting divergence from bedside engagement has furthered the distance between imaging science and COPD care providers, who have a well-trained intuition regarding disease subtype and response to therapy; this, unfortunately, doesn’t always influence what is being measured in COPD images. We hope that this series in CHEST will accelerate the necessary next step to align efforts between imaging and clinical scientists who also provide COPD care. This is important if radiologic metrics of disease activity are to be accepted as mainstream tools and truly improve patient care. Clinical experts can help by better defining clinically relevant goals. For example, we can measure bronchial wall thickening, vascular pruning, parenchymal remodeling, and a host of extrapulmonary disease–related features but, with increasingly limited resources, how do we choose our next steps? To date, we’ve trusted that answers to the science would develop organically, but perhaps we need to be more intentional. As we build a deeper understanding about lung development, susceptibility to injury, peak lung health, airway geometry, and capacity for repair, we better understand the patient with COPD. We can build on these successes and join together as pulmonary and imaging scientists to truly change how we identify early-stage disease and modify the disease trajectory. We hope that by reviewing the state of the field here and by taking a few moments to ask the right questions of the right stakeholders, we can help focus on “Stop, Look, and Listen” to maximize imaging advances that benefit patients with COPD. The authors have reported to CHEST the following: G. R. W. reports receiving consulting fees from Intellia Therapeutics, Janssen Pharmaceuticals, Pulmonx, and Vertex. He is a cofounder and equity share holder in Quantitative Imaging Solutions, a company that provides consulting services for image and data analytics. His wife works for Biogen. None declared (C. L. P.). Quantitative CT Scan Imaging of the Airways for Diagnosis and Management of Lung DiseaseCHESTPreviewCT scan imaging provides high-resolution images of the lungs in patients with chronic respiratory diseases. Extensive research over the last several decades has focused on developing novel quantitative CT scan airway measurements that reflect abnormal airway structure. Despite many observational studies demonstrating that associations between CT scan airway measurements and clinically important outcomes such as morbidity, mortality, and lung function decline, few quantitative CT scan measurements are applied in clinical practice. Full-Text PDF Lung Imaging in COPD Part 1: Clinical UsefulnessCHESTVol. 164Issue 1PreviewCOPD is a condition characterized by chronic airflow obstruction resulting from chronic bronchitis, emphysema, or both. The clinical picture is usually progressive with respiratory symptoms such as exertional dyspnea and chronic cough. For many years, spirometry was used to establish a diagnosis of COPD. Recent advancements in imaging techniques allow quantitative and qualitative analysis of the lung parenchyma as well as related airways and vascular and extrapulmonary manifestations of COPD. These imaging methods may allow prognostication of disease and shed light on the efficacy of pharmacologic and nonpharmacologic interventions. Full-Text PDF Lung Imaging in COPD Part 2: Emerging ConceptsCHESTVol. 164Issue 2PreviewThe diagnosis, prognostication, and differentiation of phenotypes of COPD can be facilitated by CT scan imaging of the chest. CT scan imaging of the chest is a prerequisite for lung volume reduction surgery and lung transplantation. Quantitative analysis can be used to evaluate extent of disease progression. Evolving imaging techniques include micro-CT scan, ultra-high-resolution and photon-counting CT scan imaging, and MRI. Potential advantages of these newer techniques include improved resolution, prediction of reversibility, and obviation of radiation exposure. Full-Text PDF