Radiological Findings in BO

Transcription

1 Radiological Findings in BO BO-Meeting 2016 Schloss Johannisberg Geisenheim - Rheingau Germany Dr. Simon Martin Department of Diagnostic and Interventional Radiology University Hospital Frankfurt

2 Bronchiolitis obliterans - Terminology Definition (histopathologic): Concentric luminal narrowing of the membranous and respiratory bronchioles secondary to submucosal and peribronchiolar inflammation and fibrosis without intralumminal granulation tissue and polyps Synonyms: Bronchiolitis obliterans = Obliterative bronchiolitis Constrictive bronchiolitis: characterized by constrictive fibroproliferative narrowing of smallairway walls Bronchiolitis obliterans syndrom (BOS): clinical manifestation of obliterative bronchiolitis in patients who have undergone lung transplantation or HSCT 2

3 Bronchiolitis obliterans with organizing pneumonia (BOOP) Cryptogenic organizing pneumonia COP Pathogenesis: 1. Flooding of plasma proteins in the alveolar lumen. 2. Formation of fibroinflammatory buds. 3. Fibrotic buds clearly delineated inside the alveolar space. Because granulation tissue are present within the lumen of distal airspaces including the bronchioles, COP had been formerly referred to as bronchiolitis obliterans with organizing pneumonia (BOOP). But, OP (and not bronchiolitis) is clearly the major lesion of COP. Cottin, V. and J. F. Cordier (2012). "Cryptogenic organizing pneumonia." Semin Respir Crit Care Med 33(5):

4 COP (BOOP) multiple patchy alveolar opacities density ranging from ground glass to consolidation with air bronchograms. Segment overlapping Cottin, V. and J. F. Cordier (2012). "Cryptogenic organizing pneumonia." Semin Respir Crit Care Med 33(5):

5 Small airways disease High-resolution computed tomography is the most useful modality for imaging of small airways disease e.g.: BO COP (BOOP) Asthma COPD Bronchiolitis

6 Small airways Membranous bronchioles Respiratory bronchioles Average diameter: mm Circumferential epithelium and lack of cartilage Cuboid epithelium Bronchial glands are absent The lumen is rounded The subepithelial connective tissue and muscle are scanty Multiple alveolar walls attached to the bronchiole serve to keep it open during expiration Average diameter: mm the smallest bronchioles that connect the terminal bronchioles to alveolar ducts deliver air to the alveoli They are interrupted by alveoli Participate in gas exchange

7 Do we see small airways disease in CT? Normal, bronchioles cannot be seen to within 20 mm of the pleural surface. Resolution of HRCT > 1 mm If visible pathological finding

8 When do we see small airways in CT? Bronchial wall thickening With/without mucoid impaction Inflammation Interstitial edema Pulmonary edema Infiltration of tumor cells Deposition of proteins, e.g. Amyloid Enlargement Bronchiolectasia Lung fibrosis Teel, G. S., et al. (1996). "Imaging of small airways disease." Radiographics 16(1):

9 Direct signs Micronodules in centrilobular distribution (respiratory bronchiolitis) Mucoid impaction: Tree in Bud

10 Respiratory bronchiolitis: Causes: Viral infect Bacterial infect Chronic bronchitis Pathological disorders: Reactive submucosal and peribronchiolar inflammation. Mucoid impaction with obliteration of the bronchioles. More common in adults Reversible

11 Bronchiolitis? Bronchitis Bronchiolitis Alveolitis Acute bronchitis Inflammation of the bronchi Acute bronchiolitis Obliterative bronchiolitis Acute alveolitis Chronic Bronchitis Bronchiectasis Constrictive bronchiolitis Emphysema Fibrosis

12 Panbronchilotis Seen mainly in Asia Characterized by foamy macrophages in bronchiolar walls in upper and lower airways Thought to follow infection Responds to makrolids High mortality

13 Direct signs Bronchiolectasia

14 Indirect signs Centrilobular emphysema

15 Direct signs Air trapping

16 Bronchiolitis obliterans Pathology: Injury and inflammation of small-airway epithelial cells and subepithelial structures lead to excessive fibroproliferation. This leads to an increased respiratory resistance, which the air must pass through the narrow bronchioles. If there is no healing in this phase, higher grade stenosis incurr, so that no air can pass and the air is scattered in the distal airways.

17 Do we see small airways in BO? In BO the luminal narrowing is invisible Indirect findings: Air trapping Why do we not see atelectasis? Pores of Kohn enable peripheral gas exchange

18 Bronchiolitis obliterans Imaging finding: Inspiratory scans may be complete normal Air trapping at expiratory HRCT No consolidation (in contrast to COP) Bronchiectasis Barker, A. F., et al. (2014). "Obliterative bronchiolitis." N Engl J Med 370(19):

19 Mosaic Perfusion Reduction in caliber of the macroscopic pulmonary vessels

20 Mosaic perfusion Pulmonary embolism

21 Swyer-James-McLeod-Syndrom Postinfecitous obliterative bronchiolitis primalarily involving the lung Unilateral hyperlucent lung that usually develops during childhood as a sequela of postinfectious bronchiolitis obliterans. Can result from various lower respiratory tract infections, including adenovirus, measles, pertussis, tuberculosis, or mycoplasma. The infection leads to inflammation and fibrosis of the respiratory bronchiolar walls and the interalveolar septa. Narrowing of bronchiolar lumens reduces ventilation and leads to compensatory hypoperfusion of the affected lung. This process also results in hyperexpansion of the peripheral airway, which contributes to the hyperlucency seen on imaging studies. Most cases become symptomatic in childhood or early adulthood. 21

22 Swyer-James-McLeod-Syndrom CT findings: Unilateral hyperlucent lung. Pulmonary vasculature small in the affect lung. Air-trapping in the affected side. Mosaic attenuation at HRCT. Bronchiectasis.

23 Swyer-James-Syndrom

24 Differential Diagnosis Asthma No radiological diagnosis. Mosaic perfusion may be identical. CT is important for imaging of complications. Silva CIS, Colby TV, Müller NL. Asthma and Associated Conditions: High-Resolution CT and Pathologic Findings. American Journal of Roentgenology. 2004;183(3):

25 Differential Diagnosis Langerhans cell histiocytosis (LCH) Micronodules more profuse Micronodules may cavitate Upper lobe predominance

26 LAM Lymphangioleiomyomatosis

27 Differential Diagnosis Panlobular Emphysema Destruction of lung parenchyma Lower lobe predominance No mosaic attenuation

28 Differential Diagnosis Desquamative Interstitial Pneumonia (DIP) Diffuse ground-glass opacities Patchy and subpleural Not bronchocentric

29 DIP ground-glass centrilobular emphysema

30 Differential Diagnosis Hypersensitivity Pneumonitis (subacute or chronic) Similar radiographic findings Chronic disease will have more fibrosis

31 Thank you for your attention