Radiological imaging of chronic obstructive pulmonary disease.

Dr/ ABD ALLAH NAZEER. MD.

Chronic obstructive pulmonary disease is defined as a preventable and treatable disease state characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases, primarily caused by cigarette smoking. Emphysema is one of its components, along with asthma and chronic bronchitis. Emphysema is defined pathologically as permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis.Chronic bronchitis is defined as chronic productive cough for 3 months in each of 2 successive years in a patient in whom other causes of chronic cough have been excluded.

Clinical presentationThe clinical features of emphysema should be distinguished from the signs and symptoms of chronic bronchitis. Patients with emphysema are hypocapnoeic and are often referred to as "pink puffers". This compares with the hypercapnoea and cyanosis of chronic bronchitis with patients referred to as "blue bloaters". In practice, features of these two syndromes coexist as chronic obstructive pulmonary disease.Patients typically report dyspnea without significant sputum production.Signs of emphysema include:tachypnoeaabsence of cyanosispursed-lip breathingchest hyperinflationreduced breath soundshyper-resonant to percussionCor pulmonale (late)

Radiographic featuresPlain filmExcept in the case of very advanced disease with bulla formation, chest radiography does not image emphysema directly, but rather infers the diagnosis due to associated features:hyperinflation:

flattened hemidiaphragm(s): most reliable signincreased and usually irregular radiolucency of the lungsincreased retrosternal airspaceincreased antero-posterior diameter of chestwidely spaced ribssternal bowingtenting of the diaphragmsaber-sheath trachea

vascular changes:paucity of blood vessels, often distortedpulmonary arterial hypertension

pruning of peripheral vesselsincreased caliber of central arteriesright ventricular enlargement

It should be remembered, however, that the most common plain film appearance of COPD is "normal" and the role of chest radiography is to eliminate other causes of lung symptoms such as infection, bronchiectasis or cancer .

CT is currently the modality of choice for detecting emphysema; HRCT is particularly effective. It should be noted, however, that there is relatively poor correlation between autopsy-proven emphysema, pulmonary function test abnormalities and CT with 20% of pathology-proven cases not being evident on CT and 40% of patients with abnormal CT having normal pulmonary function tests. CT is able to discriminate between centrilobular, panlobular, and paraseptal emphysema.Centrilobular emphysemaCentrilobular is by far the most common type encountered, and is a common finding in asymptomatic elderly patients. It is predominantly located in the upper zones of each lobe (i.e. apical and posterior segments of the upper lobes, and superior segment of the lower lobes) and has a patchy distribution. It appears as focal lucencies (emphysematous spaces) which measure up to 1 cm in diameter, located centrally within the secondary pulmonary lobule, often with a central or peripheral dot representing the central brochovascular bundlePanlobular emphysemaPanlobular emphysema is predominantly located in the lower lobes, has a uniform distribution across parts of the secondary pulmonary lobule, which are homogeneously reduced in attenuation.

Paraseptal emphysemaParaseptal emphysema is located adjacent to the pleura and septal lines with a peripheral distribution within the secondary pulmonary lobule. The affected lobules are almost always subpleural, and demonstrate small focal lucencies up to 10 mm in size.Any lucency larger than 10 mm should be referred to as subpleural blebs or subpleural bullae (synonymous).In all three subtypes, the emphysematous spaces are not bounded by any visible wall.MRI MRI is in the research phases for evaluation of lung parenchymal abnormalities like emphysema. Dynamic breathing MRI may have a future role in assessing pulmonary emphysema

EmphysemaEmphysema typically presents as areas of low attenuation without visible walls as a result of parenchymal destruction.Centrilobular emphysema

Most common type Irreversible destruction of alveolar walls in the centrilobular portion of the lobule Upper lobe predominance and uneven distribution Strongly associated with smoking.

Panlobular emphysema Affects the whole secondary lobule Lower lobe predominance In alpha-1-antitrypsin deficiency, but also seen in smokers with advanced emphysema

Paraseptal emphysema Adjacent to the pleura and interlobar fissures Can be isolated phenomenon in young adults, or in older patients with centrilobular emphysema In young adults often associated with spontaneous pneumothorax

Types of emphysema: line diagram shows the parts of secondary pulmonary lobule that are affected in different types of emphysema. Respiratory bronchioles are primarily affected by centrilobular emphysema; peripheral alveolar ducts, sacs, and alveoli in paraseptal emphysema (PLE); all the components (i.e., respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli) in panlobular emphysema (PLE), and any part in irregular or paracicatricial emphysema.

Centrilobular emphysema (CLE) and edema: A, Chest radiographs, postero-anterior and lateral views, show hyperinflation of the lungs (flattened diaphragm), increased translucency in the upper lungs with vascular attenuation and loss of arborization. B, Emphysematous spaces outlined by edema fluid filling the surrounding airspaces give an appearance of reticulation in this patient with lung edema superimposed on confluent, upper-lung predominant CLE.

Centrilobular Emphysema in a Cigarette Smoker. Axial CT image through the upper lungs shows numerous well-defined lucencies, many of which are traversed by a central vessel.

Centrilobular emphysema due to smoking. The periphery of the lung is spared (blue arrows). Centrilobular artery (yellow arrows) is seen in the center of the hypodense area.

Centrilobular pulmonary emphysema

Centrilobular emphysema: A, Transverse computed tomography images shows centrilobular hypoattenuation with upperlung predominance. Note the resemblance of the macroscopic pathologic image in Figure 4A. B, Coronal minimum intensity projection image brings out the distribution and extent of emphysema.

Centrilobular emphysema: Transverse computed tomography images in the first row and minimum intensity projection images in the second row show confluent centrilobular hypoattenuation with posterior lung predominance (arrows), Also note para-septal emphysema in the left upper lobe (arrow heads).

Panlobular emphysema (PLE) from a-1–antitrypsin deficiency: chest radiographs in postero-anterior and lateral projections show hyperinflation and increased translucency in the lower lungs with vascular attenuation, indicating PLE.

Panlobular emphysema (PLE) from a-1–antitrypsin deficiency: computed tomography images (first row) show confluent lower-lung predominant panlobular hypoattenuation, indicating PLE. The confluence, panlobular distribution, lower-lung predominance, and vascular attenuation are better shown by the coronal minimum intensity projection and maximum intensity projection images (second row).

A- Chest tomography in axial cut showing areas of panlobular emphysema in predominately lower lobes. Note cylindroids bronchiectasis and thickening of bronchial walls, most evidence in right. B- coronal reformatted showing hyper-inflation areas in lower lobes.

Ritalin lung with panlobular emphysema: chest radiographs, postero-anterior projection, and computed tomography (coronal reformatted image) show basal-predominant panlobular hypoattenuation similar to that found in a-1–antitrypsin deficiency.

Panlobular Emphysema in a Patient with Alpha-1 Antitrypsin Deficiency. Axial image through the lower lungs shows homogenous decrease in lung attenuation in both lowerlobes. Some of the interlobular septa in the right lower lobe are accentuated by the emphysema.

Panlobular emphysema

Paraseptal emphysema: computed tomography shows rectangular cysts sharing walls in subpleural upper lobes and the superior segment of the left lower lobe. Centrilobular emphysema is also evident in the upper lobes (arrows).

Paraseptal Emphysema in a Cigarette Smoker. Axial image through the upper lungs shows multiple well-demarcated subpleural air-containing spaces.

Paraseptal emphysema with small bullae.

Paracicatricial emphysema (PCE) from progressive massive fibrosis caused by silicosis: computed tomography images in lung window show conglomerate masses in theposterior upper lobes with surrounding low attenuation (arrows) indicating PCE. Hyperinflation of the anterior upper lungs is from traction by the conglomerate masses.

Coronal reformat demonstrating heterogeneous opacity in the right upper lobe and areas of centrilobular emphysema and para-septal. Tuberculosis in COPD.

Bullous emphysema: postero-anterior radiograph and coronal computed tomography multiplanar reformation and maximum intensity projection images show a large bulla in the right upper lobe with atelectasis of the adjacent lung (arrows).

Apical bleb: computed tomography through the lung apex and multiplanar reformation show a left apical bleb floating in small pneumothorax (arrows). Also note unruptured blebs in the right lung apex.

Quantification of Emphysema and Air Trapping in 66 year old Individual with GOLD Stage 3 COPD (FEV1 43% predicted) (a) Inspiratory CT: coronal image depicts voxels with CT attenuation less than -950HU indicating emphysema (14% in this case). Color coding: Indicates lobes. (b) Inspiratory CT: coronal image depicts distribution of sizes of emphysematous clusters, with color coding depending on cluster size. (c) Expiratory CT: coronal image depicts voxels with CT attenuation less than -856HU indicating air trapping (38% in this case). (d) Image map derived from co-registered inspiratory and expiratory images depicts change in voxel attenuation from inspiration to expiration.Color coding: Red indicates voxels that were less than -950 HU on inspiration and less than -856 HU on expiration (emphysema). Yellow indicates voxels that were greater than -950 HU on inspiration, but less than -856 HU on expiration (air trapping). Green indicates voxels that were less than -950 HU on inspiration and less than -856 on expiration (normal). White indicates voxels that were greater than -950 HU on inspiration but less than -856 on expiration.

Progress in Imaging COPD, 2004-2014

Follow up CT Analysis in Same Subject as Shown in Figure 6. Color coding: Same as in Figure 6. (a) %LAA-950 has increased from 14% to 23%. (b) Cluster sizes have also increased. (c)Air trapping appears to have increased from 38% to 45%. (d) Inspiratory-expiratory registration shows that only the amount of emphysema increased, while the amount of gas trapping remained constant. (e) Longitudinal registration of baseline and follow up inspiratory scans with micro mapping shows areas of stable emphysema in red, new areas of emphysema in yellow, and stable normal lung in green.

Images in representative patients with mild-to-moderate or severe chronic obstructive pulmonary disease (COPD).

Chronic bronchitis (CB) is often defined as the presence of productive cough for 3 months in two successive years in a patient in whom other causes of chronic cough, such as tuberculosis, lung cancer and heart failure, have been excluded. It can be an important pathological component of chronic obstructive pulmonary disease. (often considered as a distinct phenotype of COPD)PathologyChronic bronchitis most often results from overproduction and hypersecretion of mucus by goblet cells. This can in turn lead to worsening airflow obstruction by luminal obstruction of small airways, epithelial remodeling, and alteration of airway surface tension predisposing to collapse.

Diagnosis:A physical examination will often reveal decreased intensity of breath sounds, wheezing, rhonchi, and prolonged expiration. Most physicians rely on the presence of a persistent dry or wet cough as evidence of bronchitis.A variety of tests may be performed in patients presenting with cough and shortness of breath:A chest X-ray is useful to exclude pneumonia which is more common in those with a fever, fast heart rate, fast respiratory rate, or who are old.A sputum sample showing neutrophil granulocytes (inflammatory white blood cells) and culture showing that has pathogenic microorganisms such as Streptococcus species.A blood test would indicate inflammation (as indicated by a raised white blood cell count and elevated C-reactive protein).

Chronic bronchitis with bronchial wall thickening with increased brochovascular markings, enlarged vessels and cardiomeagly (abnormal enlargement of the heart).

Chronic bronchitis: postero-anterior radiograph (A) and computed tomography (B) show bilateral bronchial wall thickening, the so-called, ‘‘dirty lung.’’

Computed tomography (CT) scan in an elderly patient with known chronic bronchitis. The scans demonstrate thickening of the bronchial walls (purple

arrows) and bronchi filled with mucus or phlegm (blue arrows).

Computed tomography (CT) scan in patient with chronic bronchitis showing thickening of the bronchial walls (red arrows) and mucous within the bronchi (yellow arrows).

Thank You.