Lung Imaging in COPD Part 1: Clinical Usefulness

Abstract

COPD 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. This is the first of a two-part series of articles on the usefulness of imaging methods in COPD, and it highlights useful information that clinicians can obtain from these imaging studies to make more accurate diagnosis and therapeutic decisions.

Keywords: COPD; CT scan of chest; chest CT scan; comorbidities associated with COPD; emphysema; extra-pulmonary manifestations of COPD.

Figure 1

A, B, Posteroanterior (A) and lateral (B) chest radiographs from a patient with emphysema showing increased lucency of the lungs with pruning of the peripheral vasculature, flattening of the diaphragms, increased retrosternal space, widening of the intercostal spaces, kyphosis (barrel-shaped chest), and a narrowed cardiac silhouette.

Figure 2

Axial CT scan image showing chronic bronchitis. Bronchial wall thickening is present bilaterally (arrows).

Figure 3

Photomicrographs utilizing hematoxylin and eosin stains showing chronic bronchitis according to the Reid index. A, Hyperplastic mucous glands constitute > 50% of the thickness of the bronchial wall (original magnification, ×1). The Reid index equals the maximum thickness of the bronchial mucous glands internal to the cartilage (b to c) divided by the bronchial wall thickness (a to d). B, Bronchial wall pathologic features in chronic bronchitis (original magnification, ×4). The wall of this bronchus between the cartilage (far right) and the mucosa (top left) shows marked thickening by bronchial submucosal glands, smooth muscle, fibrosis, and chronic inflammation. In addition, obstruction of the bronchial lumen by mucous is present. (Figure 3A reproduced, with permission, from Travis WD, Colby TV, Koss MN, et al. Non-neoplastic Disorders of the Lower Respiratory Tract, Atlas of Nontumor Pathology. Series 1, Volume 2. American Registry of Pathology; 2002).

Figure 4

Photomicrographs showing pathologic findings in COPD. A, Collection of bronchial lymphoid tissue with a lymphoid follicle containing a GC surrounded by a rim of darker-staining lymphocytes that extend to the epithelium of both the small airways and alveolar surface (Movat stain; original magnification, ×10). B-D, Another follicle, in which the GC stained strongly for B cells (B) and a serial section of the same airway stained for CD4 cells (CD20 stain; original magnification, ×10) (C), which are scattered around the edge of the follicle and in the airway wall (CD4 stain; original magnification, ×10). An airway that has been remodeled extensively by connective tissue deposition in the subepithelial and adventitial compartments of the airway wall (D). The arrow points to the smooth muscle that separates the subepithelial from the adventitial compartments (Movat stain; original magnification, ×20). GC = germinal center. Reprinted with permission from New England Journal of Medicine, Hogg, JC, et al, The Nature of Small-Airway Obstruction in Chronic Obstructive Pulmonary Disease. Figure 2 Volume 350, p 2649. Copyright © 2004, Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.

Figure 5

High-resolution CT scan section through the lower lobes showing diffuse narrowing of the basilar airways (arrows) resulting from asthma. Note marked disparity of airway appearance when compared with adjacent pulmonary artery branches.

Figure 6

A, B, Coned-down high-resolution CT scan images through the middle and right lower lobes showing reversible airway wall changes resulting from infection: diffuse bronchial wall thickening is present before antibiotic therapy (arrow in A) that resolved after therapy (arrow in B).

Figure 7

High-resolution CT scan section through the carina showing bronchiectasis and focal mucoid retention associated with chronic bronchitis in the posterior segment of the right upper lobe (arrow). Note mild diffuse proximal airway dilatation associated with mild hyperinflation.

Figure 8

Axial thin-section CT scan image showing centrilobular emphysema with multiple well-defined lucencies of varying size without appreciable walls and some with a visible central artery.

Figure 9

A-E, CT scans showing examples of centrilobular emphysema: trace (A), mild (B), moderate (C), confluent (D), and advanced destructive (E).

Figure 10

A, B, Axial CT scan images with lung windows demonstrating mild (arrow in A) and substantial (B) paraseptal emphysema.

Figure 11

A, B, Axial (A) and coronal (B) CT scan images with lung windows showing panlobular emphysema with lower lobe predominance in a patient with α₁-antitrypsin deficiency.

Figure 12

A-C, Images showing airspace enlargement and fibrosis in a patient with lung squamous cell carcinoma. A, CT scan demonstrating lung cancer (arrowhead) and right hilar lymphadenopathy (LN). Clustered subpleural cysts are present in the left lower lobe (open arrows). These cysts are distinguished from honeycombing by their asymmetry, their heterogeneous size and shape, the absence of adjacent reticulation or traction bronchiectasis, and the presence of adjacent emphysema. B, C, Photomicrographs of pathology specimens disclosing areas of airspace enlargement and alveolar wall thickening and fibrosis (arrows): low magnification (B; hematoxylin and eosin stain; original magnification, ×2) and high magnification (C; hematoxylin and eosin stain; original magnifcation, ×4). (Fig 12B and Fig 12C courtesy of Dr Joungho Han, Samsung Medical Center.)

Figure 13

A, B, Axial (A) and coronal (B) CT scan images from a patient with severe emphysema and a 16-mm solid nodule in the left upper lobe found to be lung cancer.

Figure 14

A-C, Images showing combined pulmonary fibrosis and emphysema. A, B, CT scan images showing moderate centrilobular emphysema, cysts of varying sizes (open arrows), and reticular abnormality (closed arrow), especially in the lower lungs. The larger cysts likely represent a component of airspace enlargement with fibrosis. C, Photomicrograph using hematoxylin and eosin stain (original magnification, ×2) showing dense thickening and fibrosis of interlobular septa (large closed arrow), fibrous alveolar wall thickening (small closed arrows), cellular alveolar wall inflammation, microscopic honeycomb cyst (open arrow), and emphysema. Chronically heterogeneous parenchymal fibrosis suggests the presence of usual interstitial pneumonia. (Fig 14C provided courtesy of Dr Joungho Han, Samsung Medical Center.)

Figure 15

A-C, CT scans showing interstitial lung abnormality (ILA) in two different patients without suspected lung disease. A, CT scan showing nonfibrotic interstitial lung abnormality. B, Axial CT scan showing patchy ground-glass opacity in the right lower lobe and multiple well-defined cysts in both lower lobes. C, CT scan obtained through the lung bases showing fibrotic ILA: subpleural predominant reticular abnormality (yellow arrow) with traction bronchiectasis (arrowheads).

Figure 16

A, B, Posteroanterior (A) and lateral (B) radiographs of a patient with COPD and bronchiectasis, as demonstrated by tubular lucencies (arrows) at the lung bases. C, Coronal CT scan image (C) confirms bronchiectasis (arrow). Also note flattening of the diaphragms on the lateral radiograph (B).

Figure 17

Axial contrast-enhanced CT scan image obtained at the bifurcation of the main pulmonary artery in a patient with pulmonary hypertension demonstrating a dilated (41 mm) main pulmonary artery (number sign), larger in caliber than the adjacent ascending aorta (27 mm; asterisk), suggesting pulmonary hypertension.

Figure 18

A, B, Frontal (A) and lateral (B) chest radiographs demonstrating tapering of the pulmonary vessels, also known as vascular pruning, and dilatation of the main pulmonary artery segment (arrow), consistent with pulmonary hypertension. The lungs are hyperaerated and flattening of the diaphragms is present, evident of emphysema. C, Coronal CT scan image confirming vascular pruning (red circle).

Figure 19

A-C, Images showing a saber-sheath trachea. A-C, Axial CT scan image with lung windows (A), multiplanar volume reformatted image (B), and virtual bronchoscopic image of trachea (C) in a patient with severe emphysema. Coronal narrowing (arrow) of the trachea with widening of the sagittal diameter are present, consistent with a saber-sheath trachea.