Role of HRCT in Diagnosis of Asbestos Related Pleuro Pulmonary Disease

Transcription

1 Cairo University Role of HRCT in Diagnosis of Asbestos Related Pleuro Pulmonary Disease ESSAY Submitted for partial fulfillment of Master degree in Radio-diagnosis By Rania Adel Abd ElRahem Elghetany (M.B.B.CH., Cairo University) Under Supervision Of Dr.Naglaa Mohamed Abdel Razek,MD Assistant Professor of Radiodiagnosis Faculty of Medicine Cairo University Dr.Mohamed Ali Abd Elaziz Salem,MD Lecturer of Radio-diagnosis Faculty of Medicine Cairo University Faculty of Medicine Cairo University 2012 I

2 Abstract The inhalation of asbestos fibers may lead to a number of respiratory diseases, including benign pleural effusion, pleural plaques, asbestosis, lung cancer and malignant mesothelioma. Although exposure is now regulated, patients continue to present with these diseases because of the long latent period between exposure and clinical disease. With its ability to show lung abnormalities not appreciated on conventional radiographs, HRCT is considerably more sensitive than conventional radiography in the detection of asbestosis, especially in early or mild disease. Common HRCT scan findings in early asbestosis are intralobular, small, rounded or branching opacities; thickened interlobular septa; subpleural curvilinear lines; and parenchymal bands. The interlobular septal lines typically represent fibrosis. With progression of disease, honeycombing is seen. Key words: HRCT- Asbestosis Asbestos related pleuropulmonary diseases II

3 Acknowledgment First and foremost thanks are due to Allah the beneficent and merciful of all. I would like to express my deep gratitude and appreciation to Dr.Naglaa Mohamed Abdel Razek, MD Assistant Professor of Radiodiagnosis, Faculty of Medicine, Cairo University, for her continuous help and unlimited support. I am greatly indebted and grateful to Dr. Mohamed Ali Abd Elaziz Salem, Lecturer of Diagnostic Radiology, Faculty of Medicine, Cairo University, for his continuous encouragement to bring this work to the attempted goal. This work wouldn t come to light without the help of my family members, their patience and co-operation. III

4 List of Figures Figure Title Page Figure (1) A. Inflated and fixed lung specimens B. A schematic drawing of the lung 5 Figure (2) A. Details of lung parenchyma B. A magnified view of Fig. 2A 6 Figure (3) An enlarged view of the alveolar dome shows Kohn pore as small hole 7 Figure (4) Photograph of a real honeycomb 7 A Contact radiograph of respiratory bronchiole with barium sulfate The constant distance from respiratory bronchiole Figure (5) B to the nearest septal structures of the secondary 8 lobule. C Histology of the respiratory bronchiole D Magnified view of the respiratory bronchiole Figure (6) The lobar and segmental branching pattern Macroscopic specimen of the left lower lobe A inflated with air 10 Figure (7) B 3D CT of the specimen. Note the rich network pattern especially in the lower portion. 12 C HRCT shows subpleural structure as thin lines along visceral pleura D Histology confirms subpleural lymphatics Figure (8) Secondary pulmonary lobule. `14 IV

5 Figure (9) The secondary pulmonary lobule HRCT 15 Figure (10) Normal HRCT. 16 Figure (11) Figure (12) Normal pleura. Virtual endoscopy at the level of the middle trachea (A) and the carina (B) Figure (13) (A) Inspiratory and (B) end-expiratory HRCT images 29 Figure (14) HRCT for suspected interstitial fibrosis 32 Figure (15) Chest X-ray vs HRCT technique 33 Figure (16) Conventional CT technique vs HRCT technique 34 High-resolution computed tomogram of a 67-year-old man Figure (17) with idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP). 37 Figure (18) Sarcoidosis. Axial HRCT image. 38. Figure (19) Miliary tuberculosis Axial HRCT image 38 Figure (20) Figure (21) Figure (22) Usual interstitial pneumonia (UIP). Axial (A) and coronal (B) images HRCT Scleroderma. (A) Axial image (B) Coronal image (A) Asbestos bodies on histology (B) Ferruginous bodies in iron stain V

6 (C) Chest x-ray showing pleural thickening, mesothelioma, and asbestosis (D)CT chest showing increased intralobular septa, subpleural curvilinear lines from asbestosis Figure (23) Pathologic features of asbestosis 54 Figure (24) Figure (25) Figure (26) Figure (27) Figure (28) Figure (29) Figure (30) Figure (31) Figure (32) A case was diagnosed as asbestosis based on chest x-ray,ct, and pathology. Photograph of a macroscopic section of an exophytic pale carcinoma in the lower lobe bronchus shows distal mucoid impaction Chest x-ray showing pleural thickening, mesothelioma, and asbestosis Posteroanteriorly chest radiograph of a man with asbestosrelated pleural disease. Coronal CT scan obtained with mediastinal window settings shows pleural plaques Prone HRCT image of man with asbestos-related pleural disease Contrast-enhanced CT image of a 67-year-old man with mesothelioma shows circumferential right pleural thickening. CT scan of an asbestos-exposed person shows bilateral circumferential diffuse pleural thickening A patient with prior asbestos exposure has focal areas of pleural thickening or pleural plaques Figure (33) Rounded atelectasis. CT scan 76 Figure (34) Images from a woman who died at age 75 years after 31 years in the asbestos textile industry and 25 years of exposure 78 VI

7 Figure (35) Images from man who died at age 56 years after 42 years in the asbestos textile industry and 22 years of exposure 78 Figure (36) Early asbestosis. HRCT scan 79 Figure (37) HRCT for suspected asbestosis 79 Figure (38) Coronal HRCT image of a 76-year-old man with asbestosis 80 Figure (39) Figure (40) Figure (41A,B) Figure (42A,B) Figure (43A,B) Figure (44) Figure (45) CT scan obtained with mediastinal window settings in a 82 patient who had malignant pleural mesothelioma Coronal contrast-enhanced CT scan obtained with mediastinal window settings in a patient who had malignant 83 pleural mesothelioma A) Posteroanterior chest radiograph representing typical pleural calcifications and a newly developed pleural mass in the left apex. 84 (B) CT scan of the thorax with contrast demonstrating pleural calcifications A-CT,lung window show Pleural thickening and pleural effusion 85 B-CT, mediastinal window showpleural thickening and pleural effusion Classic idiopathic pulmonary fibrosis 93 Highresolution CT shows idiopathic pulmonary fibrosis 94 (IPF). Transverse thin-section CT images show examples of the coarser fibrosis seen with (a) asbestosis (prone image), as 96 compared with the fibrosis seen with (b) biopsy-proved NSIP. VII

8 Figure (46) Initial (A) and follow-up (B) HRCT scans in a 39-year-old woman with who had repeated episodes of summer type HP for several years 98 Figure (47A,B) Figure (48A,B) Scleroderma. CT(A,B) Two patients with scleroderma showing ground-glass opacification in association with traction bronchiectasis and a fine reticular pattern The NSIP pattern on CT in patients who have (A) RA and (B) SS Figure (49) Asbestosis. Axial image from contrast enhanced chest CT 102 Figure (50) Section of an HRCT showing amiodarone lung. 104 VIII

9 List of Tables Table Title Page Table (1) Differential Diagnosis of ILDs Based on Radiologic Findings 35 Table (2) Potential sources of occupational and environmental asbestos exposure 44 Table (3) Symptom, prevalence and treatment of asbestosrelated lung disease 61 Table (4) Criteria for parenchymal fibrosis and the classification system of fibrosis severity on high resolution computed tomography of the lungs. 81 Table (5) Differential Diagnosis: asbestosis from idiopathic pulmonary fibrosis 96 Table (6) Drug-induced ILD 103 IX

10 List of abbreviations ATS BAL CT CTDs DPT FOV FDG GGO HU HRCT HP IPF ILD ILO American Thoracic Society Broncho alveolar lavage Computed Tomography Connective Tissue Diseases Diffuse pleural thickening Field of view Fluorodeoxyglucose Ground glass opacity Hounsfield Unit High resolution computed tomography Hypersensitivity pneumonitis Interstitial pulmonary fibrosis Interstitial Lung Disease International Labor Organization X

11 KV(p) MA MDCT MIP minip MPM NSIP PET RA SSc TBM UIP Kilovolt Milliamper Multidetector computed tomography Maximum intensity projection Minimum intensity projection Malignant pleural mesothelioma Non specific interstitial pneumonia Positron Emission Tomography Rheumatoid arthritis Systemic sclerosis Tracheobronchomalacia Usual interstitial pneumonia XI

12 Table of Contents Title page Introduction & Aim of Work 1 Review of Literature Structural And Radiological Anatomy Of The Lung. 4 Technical aspects of High-Resolution Computed Tomography 23 Epidemiology and pathogenesis of asbestos exposure 41 Role Of HRCT In Dignosis Of Asbestos Related Pleuropulmonary Diseases 62 Role of HRCT in differential Diagnosis of asbestosis 89 Summary & Conclusions 105 References 108 Arabic Summary 115 XII

13 Introduction Asbestos is the generic term used for the group of fibrous mineral silicates of magnesium and iron whose chemical and physical properties make it ideal for a variety of commercial and industrial uses. Asbestos natural resistance to heat and fire, tensile strength, flexibility, and insulating properties have led to its use in more than 300 applications including floor tiles, boiler and pipe insulation, roofing. Asbestos is classified into two groups based on its physical properties: the serpentines, which tend to be wavy and long and the a amphiboles, which are straight and rod like.(sam Chum et al, 2008). The common asbestos induced diseases include pleural effusion, pleural plaques, diffuse pleural thickening, asbestosis, malignant mesothelioma and bronchogenic carcinoma. (Huw D et al, 2002). Clinical onset of symptoms in patients with asbestosis generally occurs approximately 20 years after initial exposure. The signs and symptoms associated with asbestosis are for the most part non specific and resemble those found in other restrictive interstitial lung disease. The most prominent symptom, and usually the earliest, is the insidious onset of dysnea on exertion this is often progressive despite discontinuation of asbestos exposure. Other common symptoms include a persistent dry or productive cough, chest tightness and wheezing. (Sam Chum et al, 2008). HRCT can be useful in detecting early changes associated with asbestosis and in helping clarify questionable pleural and parenchymal finding and in diagnosis HRCT clarify the difference between asbestos-associated pleural plaque and soft tissue densities mesothelioma. In the diagnosis of asbestos-related lung disease, HRCT should be considered not only for workers with positive finding on chest X-ray but also workers with 1

14 specific finding on spirometry, occupational history, smoking history, and past history of respiratory disease or with respiratory symptom such as cough and dyspnea. ( Lee HJ et al, 2006). In diagnosis of asbestos lung biopsy is seldom warranted unless another potentially reversible cause of interstitial lung disease is strongly suggested A less invasive mean of establishing exposure is broncho alveolar lavage, which can detect the presence of asbestos bodies. (Sam Chum et al, 2008). HRCT including prone scan is a sensitive, reliable means of detecting thoracic abnormalities in individual exposed to asbestos. Prone scan allow basal structural abnormalities to be reliably distinguished from gravity related physiologic phenomena. Major CT finding in early asbestosis include thickened intra lobular lines, subpleural curvilinear lines, pleural-based nodular irregularities, patchy area of ground glass attenuation, small cystic spaces and small areas of hypoattenuation. (W.Kim et al, 2001). Asbestosis and idiopathic pulmonary fibrosis have similar histo pathological appearance and similar radiographic manifestation. HRCT may be helpful in differentiating asbestosis from idiopathic pulmonary fibrosis. CT finding suggest that bronchial obstruction in the sub pleural region was more prominent in asbestos than in idiopathic pulmonary fibrosis, whereas bronchial dilatation was more prominent in idiopathic pulmonary fibrosis than in asbestosis. These differences may be related to underlying morphology of each process. (Masanori akira et al, 2003). It is important to be aware of the clinical, radiologic, and pathologic characteristics of asbestos-related disease, which appear to have the longest latency. (Huw D et al, 2002). 2

15 Aim of work The aim of this study is to clarify the role of HRCT in diagnosis of asbestos related pleuro pulmonary diseases which range from pleural effusion and pleural plaque to lung cancer and malignant mesothelioma. 3

16 STRUCTURAL AND RADIOLOGICAL ANATOMY OF THE LUNG 4

17 STRUCTURAL ANATOMY OF THE LUNG There are two kinds of lung structures, parenchymal and nonparenchymal structures. The lung parenchyma resembles a sponge, and occupies 90% of total lung volume. Non-parenchymal structures consist of the bronchial tree, pulmonary vessels, and interlobular septa as in (Figure 1A, B).the bronchi and pulmonary arteries run together, alternated by pulmonary veins (Itoh et al., 2001). Figure 1 A. Inflated and fixed lung specimens show bronchial tree, pulmonary vessels, and interlobular septa, which form non-parenchymal structures. Lung parenchyma occupies 90% of total lung volume. B. A schematic drawing of the lung based on a contact radiograph of the specimen is shown. Note that pulmonary artery and vein run alternatively in the lung (Itoh et al., 2001). Lung Parenchyma A closer look at the lung parenchyma reveals numerous air-containing passages and intervening fine structures. Both are distributed evenly as seen in the 0.5mm thick lung slice shown in (Figure 2). The passage and intervening 5

18 structures correspond to alveolar ductal lumens and alveoli, respectively (Schneider et al., 2000). Fig. 2 A. Macroscopic lung specimen show Details of lung parenchyma consisting of numerous air containing passages and intervening fine structures, corresponding to alveolar ducts and alveoli. B. A magnified view of Fig. 2A (Schneider et al., 2000). Alveolar Duct and Alveoli Usually, 7 or 8 alveoli surround the alveolar ductal lumen. The interalveolar septum is a thin membrane, and the overall shape of the alveolus is polyhedral. The diameter of the ductal lumen is 0.3mm, and the mean size of the alveolus is 0.2mm. The alveolar duct length is about 1mm in the long axis. The inner surface of the alveolar duct is covered by a sheet of alveoli. The shape of each alveolar entrance is not round but polygonal, like a honeycomb. At higher magnification, a small hole in the alveolar dome can be seen, which is Kohn pore as in(fig.3). (Itoh et al., 2001).The photographs of a real honeycomb show the entrance of each cell as hexagonal in shape as in (Fig. 4). (Schneider et al., 2000). 6

19 Fig. 3 An enlarged view of the alveolar dome shows Kohn pore as small hole (arrow) (Itoh et al., 2001).. Fig. 4 Photograph of a real honeycomb. Note the hexagonal shape of the entrance of each cell (Schneider et al., 2000). Respiratory Bronchiole The respiratory bronchiole is called the transitional zone because part of the bronchiolar wall is replaced by alveoli. The number of alveoli increases as the respiratory bronchioles branch out as in (Figure. 5A). The distance from the respiratory bronchiole to the nearest septal structures of the secondary lobule is constant. For example, in the case shown in (Figure. 5B), the respiratory bronchiole is separated from the pulmonary vein by lung parenchyma. The 7

20 distance between the two is maintained at 2mm. On histological examination of the respiratory bronchiole, the bronchiolar wall, which is remote from the pulmonary artery, is replaced by a sheet of alveoli as in (Figure. 5C). A closeup image reveals these alveoli form a double sheet of alveoli where they abut the recurrent branch of the alveolar duct as in (Figure. 5D) (Schneider et al., 2000). Figure 5 A. Contact radiograph of respiratory bronchiole with barium sulfate, showing an increase in the number of alveoli as the respiratory bronchiole branches out. B. Note the constant distance from respiratory bronchiole to the nearest septal structures of the secondary lobule. C. Histology of the respiratory bronchiole. D. Magnified view of the respiratory bronchiole demonstrating the double sheet of alveoli abutting the recurrent branch of alveolar duct (Schneider et al., 2000). Non-parenchymal Structures Alveolar Capillary Beds and Venules The important structural component of the interalveolar septum is the alveolar capillary. The alveolar capillary is a dense network consisting of a number of irregular polygons. 8