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CT imaging of the spectrum of diseases causing air trapping ECR 2007: March 9 - 13 Vienna, Austria Start Home How to show Objective Index Definition Causes Reference Home CT imaging of the spectrum of diseases causing air trapping Authors: CMU Siriraj Hospital Juntima Euathrongchit, MD. Nisa Muangman, MD. Jeffrey P Kanne, MD. Eric J Stern, MD. Home How to show Objective Index Definition Causes Reference How to Navigate Simply view as a slide show or Click on Icon on the right lower corner for next slide Icon on the right lower corner for previous slide Click on each topic from table of contents to view each topic directly Home How to show Objective Index Definition Causes Reference Objective To systemically review the CT imaging spectrum of diseases causing air trapping Home How to show Objective Index Definition Index • Definition • Causes of air trapping: – The airway disease – The lung parenchymal disease – The cardiovascular disease – Miscellaneous • Reference Causes Reference Home How to show Objective Index Definition Causes Reference Definition Air Trapping A condition that there is an abnormal retention of gas within a lung or part of a lung, especially during or after expiration [1]. Home How to show Objective Index Definition Causes Reference Definition: air trapping Normal breathing Inhale Exhale Lung attenuation normally increases during exhalation (ovals) The anterior arching of the posterior membrane confirms exhalation (arrow) Home How to show Definition: Objective Index Definition Causes Reference air trapping Air trapping • Note the mostly normal right lung with patchy areas of low attenuation during expiration • CT images show that the lingula does not increase in attenuation as expected indicating air trapping (oval) •Diagram shows air trapping in LUL. Inhale Exhale Home How to show Objective Index Definition Causes Reference Definition: normal vs air trapping Normal vs Air trapping CT images compare between normal breathing and air trapping. • Note the mostly normal right lung with patchy areas of low attenuation during expiration. • The lingula does not increase in attenuation as expected indicating air trapping. Home How to show Objective Index Definition Causes Reference Definition: normal vs air trapping Cine images show normal breath and air trapping, which is accentuated on expiration Normal breathing Air trapping Home How to show Objective Index Definition Causes Causes Air trapping from The airway disease • The lung parenchymal disease • The cardiovascular disease Miscellaneous Reference Home How to show Objective Index Definition Causes Reference Causes: airway disease Airway disease • Both large and small airway diseases are the main causes of air trapping on CT. • The small airway or bronchiolar diseases are more common than diseases of bronchi. Small airway disease vs Large airway disease Home How to show Objective Index Definition Causes Reference Causes: airway disease Small airway (bronchiolar) disease • Inflammation is the most common cause of bronchiolar disease, referred to as bronchiolitis. • Bronchiolar disease can be grouped into four categories: (i) Tree-in-bud pattern; (ii) Poorly-defined centrilobular opacities; (iii) Decreased lung attenuation or air trapping; and (iv) Focal, diffuse ground-glass opacity, consolidation or both [2]. Home How to show Objective Index Definition Causes Reference Causes: airway disease Small airway (bronchiolar) disease Air trapping pattern is still seen in all groups :Constrictive bronchiolitis (obliterative bronchiolitis) Swyer Jame syndrome Asthma. Sarcoidosis Extrinscic alveolitis Infectious bronchiolitis Diffuse panbronchiolitis Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - BO Constrictive bronchiolitis (obliterative bronchiolitis) 1 • Most common cause of air trapping pattern • Due to bronchiole narrowing or obliteration from concentric fibrosis involving exclusively the submucosal and peribronchiolar tissues of terminal and respiratory bronchioles [2]. Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - BO Constrictive bronchiolitis (obliterative bronchiolitis) 2 Table: Etiology of obliterative bronchiolitis. Post infectious BO - Bacterial, Mycoplasma, viral (esp. Measles, Respiratory Syncytial virus, Adenovirus, Influenza, Parainfluenza and Cytomegalovirus), - Sequela of PCP, HIV, viral infection or both in AIDS Toxic fume BO - Exposure gas: Nitrogen dioxide (Silo-filler’s lung), sulfur dioxide, ammonia, chlorine, phosgene and ozone Idiopathic BO associated with connective tissue disease RA, Polymyositis BO associated with drug therapy Penicillamine, Gold BO as a complication of lung or bone marrow transplantation Chronic lung allograft rejection Neuroendocrine hyperplasia (carcinoid) Children surviving bronchopulmonary dysplasia (BPD) Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - BO Constrictive bronchiolitis (obliterative bronchiolitis) 3 Air trapping on expiratory HRCT images, clinical characteristic, and physiologic features often are diagnostic for obliterative bronchiolitis. On dynamic CT scanning, look for small caliber and paucity of vessels within the low attenuation regions, reflecting hypoxic reflex vasoconstriction, consequent to bronchiolitis and impaired ventilation Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - SJS Swyer Jame syndrome 1 • Post-infectious obliterative bronchiolitis occurs in infancy or early childhood, before the age of 8 and full alveolar developmenti. • Many organisms implicated: adenovirus, measles virus, B. pertussis, M. tuberculosis, and Mycoplasma. • Classic chest radiograph findings are a unilateral hyperlucent lung with attenuated ipisilateral peripheral and central pulmonary arteries and a small or normal hemithorax. • HRCT shows focal, patchy, or diffuse air trapping.[3] Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - SJS Swyer Jame syndrome 2 Note radiolucent area of air trapping in the RUL with mild dilatation of the RUL bronchi with peribronchial wall thickening (arrow) Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - asthma Asthma A reversible reactive small airways disease, occurring in up to 5% of adults and 10% of children [4]. HRCT: - Bronchial wall thickening (the most common finding), - Narrowing of bronchial lumen, bronchiectasis - Mosaic perfusion and air trapping on expiratory CT scans [5-7]. - Full inspiratory CT scan may be normal. - Full expiratory HRCT examination may show patchy air trapping Home How to show Objective Index Definition Causes: airway disease - Small airway - asthma Asthma Coronal, sagittal and axial images show prominent peribronchial wall (arrow) and air trapping in left lung apex and RML (oval) on expired phase (cine images) expired Causes Reference Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - sarcoidosis Sarcoidosis 1 • Systemic disease of unknown etiology characterized by noncaseating granulomata • Chest involved in about 90% of cases [9] • Characteristic HRCT findings are small perilymphatic nodules in peribronchovascular, subpleural, and interlobar septal distributions and mediastinal and hilar lymphadenopathy • Air trapping is caused by bronchial or bronchiolar obstruction from endobronchial granulomata or enlarged peribronchial lymph nodes • 89 -95 % of cases show air trapping [10, 11] Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway -sarcoidosis Sarcoidosis 2 • Air trapping can occur at multiple airway levels: sublobular, subsegmental, and segmental bronchi • Air trapping may be the result of accumulation of secretions in large and small airways, bronchial hyperactivity from chemical mediators, and pulmonary fibrosis. Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - sarcoidosis Sarcoidosis 3 APW N Precarinal N L hilar N Subcarinal N Typical finding: Diffuse small nodules, subpleural nodules (arrow) and nodules along interlobar fissure (yellow box), predominately. Note mediastinal and hilar adenopathy Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - sarcoidosis Sarcoidosis 4 CT upper lung fields show heterogeneous attenuation of lung parenchyma corresponding to the air trapping (mosaic perfusion) at the low density areas. Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - HP Extrinsic allergic alveolitis 1 • Also known as hypersensitivity pneumonitis • Characterized by a type IV hypersensitivity reaction to inhaled, primarily organic, particles • Two most common forms are farmer’s lung and bird breeder’s lung. • The combination of clinical antigen exposure, characteristic signs and symptoms, and distinctive HRCT findings are often diagnostic Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway - HP Extrinsic allergic alveolitis 2 • HRCT (subacute): – Diffuse poorly-defined centrilobular nodules and patchy ground-glass opacities, correlating with interstitial pneumonitis, cellular bronchiolitis, and small noncaseating granulomata – Most common affects mid and upper lungs. – Air trapping may also be present – The most common HRCT patterns are decreased attenuation and mosaic perfusion (86%), ground-glass opacity (81%), small nodules (54%), and a reticulation (36%) [12] Home How to show Objective Index Definition Causes Causes: airway disease - Small airway - HP Extrinsic allergic alveolitis 3 Diffuse groundglass opacities in both lungs Note a few areas of air trapping in both upper lobes (arrow) Reference Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway – infectious bronchiolitis Infectious bronchiolitis • A form of follicular bronchiolitis causing by viral or Mycoplasma pneumoniae infection in the general population [2]. • Immunocompromised patients and those with poor airway clearance are also at risk for fungal infection • Iinfectious bronchitis and bronchiolitis are increasingly being recognized as causes of acute lung symptoms in AIDS. Radiologic findings: - Bronchial wall thickening on chest radiograph - Small centrilobular nodules and tree-in-bud opacities, representing inflammed bronchioles impacted with debris [2] Home How to show Objective Index Definition Causes Reference Causes: airway disease - Small airway – infectious bronchiolitis Infectious bronchiolitis Coronal and sagittal reconstruction images and cine axial images show tree in bud pattern in both lungs and mild heterogeneous attenuation of lung parenchyma Home How to show Objective Index Definition Causes: airway disease - Small airway - DPB Diffuse panbronchiolitis Typically seen in Southeast Asia patients. The characteristic feature on HRCT : “tree-in-bud” of secretion filled dilated bronchiole. Otherwise: - bronchiolectasis, - bronchiectasis, and - mosaic opacities. [7] Causes Reference Home How to show Objective Index Definition Causes Causes: airway disease - large airway • Large airway (bronchial) disease It could be from • Endobronchial tumor: primary vs secondary • Bronchiectasis • Tracheobronchomalacia Reference Home How to show Objective Index Definition Causes Reference Causes: airway disease - large airway – endobronchial tumor Large airway (bronchial) disease Endobronchial tumor Most significant cause of air trapping. Endobronchial tumor could be from :– Primary tumor such as bronchogenic carcinoma, carcinoid or adenoid cystic carcinoma, etc. – Metastasis from breast, colon, GU, melanoma, Kaposi’s sarcoma. Home How to show Objective Causes: airway disease - Index Definition Causes Reference Large airway: primary tumor Primary tumor: Bronchogenic carcinoma 1 • The most common cause of cancer-related death worldwide • No good effective screening method to early diagnosis • The radiologic features depend on location and size of the lesion. • Tumor may intrinsically occlude central airways or extrinsically compress the airway lumen, resulting in obstructive pneumonitis, which is more common than air trapping. • When the tumor involves the adjacent pulmonary artery, the supplied parenchyma may have lower attenuation because of hypoperfusion Home How to show Objective Causes: airway disease Index Definition Causes - Large airway: primary tumor Bronchogenic carcinoma 2 Axial lung images at the arch and carinal level and cine axial mediastinal images, closed up at the endobronchial mass (squamous cell CA) in the left main bronchus (arrow), producing air trapping in LUL (oval) Reference Home How to show Objective Causes: airway disease Index Definition Causes - Large airway: primary tumor Bronchogenic carcinoma 3 Axial and coronal show LLL bronchial obstruction by tumor (arrow), resulting of obstructive pneumonitis distally and lucent area of air trapping in superior segment of LLL (oval). Note paraseptal emphysema at both lung apices. Reference Home How to show Objective Index Definition Causes Reference Causes: airway disease - Large airway: primary tumor Primary tumor: Carcinoid, Adenoid cystic adenoma 1 Carcinoid tumor : An uncommon lung neoplasm, approximately 0.5 – 2.5% of all lung tumors [13], mainly in female with mean age of 45 years old. In spite of a neuroendocrine tumor, carcinoid syndrome is a rare, unless it has liver metastases. There are two kinds of carcinoid, typical one that is much more common than atypical one, divided by basic histopathology. Usually tumor is located centrally and shows large and chunky calcification up to 39% of lesions as demonstrated by CT scans. When a carcinoid tumor partially occludes a bronchus, it can cause expiratory air trapping on dynamic CT [13]. Adenoid cystic carcinoma and Mucoepidermoid carcinoma: rare conditions. Only a report case of them reveal the mimic MacLeod’s syndrome or unilateral hyperlucent lung [14] [15]. Home How to show Objective Index Definition Causes Reference Causes: airway disease - Large airway: primary tumor Primary tumor: Carcinoid, Adenoid cystic adenoma 2 A small well defined intrabronchial tumor (caricinoid) presented at the right intermediate bronchus (arrow). Note groundglass opacity at posterior portion of the both hemithorax could be aspiration. Home How to show Objective Index Definition Causes Reference Causes: airway disease - Large airway: metastasis Metastatic diseases Endobronchial or endotracheal metastases: • Rare conditions. The incidence from autopsy shows widely range from 2% to 50% [16]. • The common primary tumors are carcinoma from the breast, colorectum, and kidney as well as melanoma. • The airway obstruction is an important mechanism for radiologic findings, which are included atelectasis, obstructive pneumonitis or air trapping. Home How to show Objective Index Definition Causes Reference Causes: airway disease - Large airway: metastasis Metastatic diseases Metastatic breast carcinoma Lymphatic metastasis at the right hilum with bronchial invasion, resulting of segmental atelectasis and bronchiectasis of RLL. Also note multifocal lucency areas of air trapping in RLL Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - bronchiectasis Bronchiectasis 1 • An irreversible dilation of the bronchi resulting from destruction of the elastic and muscular components [20]. There are both congenital and acquired causes of bronchiectasis. • Air tapping or atelectasis of the affected lobe are commonly present. • Three categories based on the morphology of dilated bronchi : – cylindrical bronchiectasis (mild) – varicose bronchiectasis (moderate) – cystic bronchiectasis (sever form disease) Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - bronchiectasis Bronchiectasis 2 HRCT is a standard technique to diagnose bronchiectasis HRCT shows : - loss of normal tapering of bronchus and bronchial wall thickening - tram-track appearance when scan plane is parallel to the dilated bronchus - signet ring pattern when plane is perpendicular to the bronchus - bead-like appearance in varicose type - cystic dilatation of the bronchi, sometimes filled with liquid Home How to show Objective Index Definition Causes Causes: airway disease Large airway - bronchiectasis Bronchiectasis 3 • Two levels of thin slice CTA demonstrate – tram-track of dilated RUL bronchi – Signet ring sign in RLL (arrow) with small fluidfilled dilated bronchus (ovals) Reference Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - bronchiectasis Bronchiectasis 4 • Thin slice CTA demonstrate – tram-line of dilated bronchi in LUL and signet ring pattern in the apical segment of RUL (arrow). – General heterogeneous attenuation of lung parenchyma and illdefined low density areas of air trapping, peripherally Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - bronchiectasis Bronchiectasis Ring = dilated bronchi 5 Signet = correlated pulmonary artery String of pearl Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - bronchiectasis Bronchiectasis 6 Marked dilatation of bronchi, containing variable amounts of pooled secretions HRCT: cluster of grapes with air-fluid level Associated with obliterative & inflammatory bronchiolitis (85%) Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - Tracheomalacia Tracheobronchomalacia 1 • Characterized by increased tracheal and bronchial compliance, which can result in a functional obstruction or stenosis. Disease is usually focal but can be be diffuse. • Acquired tracheobronchomalacia is more common than congenital – Most common: ischemic necrosis from an overinflated endotracheal tube balloon cuff – Other causes include trauma, radiation therapy, tracheaoesophageal fistula, Wegener granulomatosis, and relapsing polychondritis • On expiratory CT scan, tracheobronchomalacia is characterzied by collapse of the airway with approximately 60-100% loss of full inspiratory cross-sectional area [20]. Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - Tracheomalacia Tracheobronchomalacia 2 • Air trapping in tracheobronchomalacia was reported by J Zhang and colleagues [24]. • They found that most tracheobronchomalacia cases in their hospital show air trapping, and the lobular pattern is the most commonly seen on dynamic expiratory CT scans. Though the control group shows lobular air trapping, the degree or score of air trapping is more severe in tracheobronchomalacia patients. • The cause of air trapping in tracheobronchomalacia is unclear, but it may reflect chronic small airways disease due to abnormal respiratory mechanics related to excessive central airways collapse. Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - Tracheomalacia Tracheobronchomalacia 3 Inspired vs expired Note the marked difference in size of the tracheal lumen during inspiration (arrow) and expiration (double arrow) Home How to show Objective Index Definition Causes Reference Causes: airway disease Large airway - Tracheomalacia Tracheobronchomalacia 3 Volume rendered 3D reconstruction of the trachea from a patient with tracheomalacia Note the near complete collapse of the trachea, and a small diverticulum arising from the right main bronchus, inferiorly Home How to show Objective Index Definition Causes Causes Air trapping from The airway disease • The lung parenchymal disease • The cardiovascular disease Miscellaneous Reference Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma II Air trapping associated with lung parenchymal disease – Lung emphysema – Cystic disease: • CCAM, LAM, Langerhan’s histiocytosis – Infiltrative disease: • Thalassemia, Intralobar pulmonary sequestration Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma – emphysema Lung emphysema 1 • An abnormal, permanent enlargement of the air spaces distal to the terminal bronchioles accompanied by destruction of the alveolar wall and without obvious fibrosis. • Three main types classified by anatomical structure involved: – centrilobular – panlobular – paraseptal Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma – emphysema Lung emphysema 2 Centrilobular emphysema the most common form, associated with cigarette smoking, localized at upper lobe, predominately. RUL shows lucent area at the centrilobular area, representing of centrilobular emphysema (oval). Note central artery is seen in these lucent areas (arrow). Home How to show Objective Index Definition Causes Causes: lung parenchyma – emphysema Lung emphysema 3 Panlobular emphysema • Associated with alpha-1-antitrypsin deficiency • Basal predominant • Can mimic the air trapping of obilterative bronchiolitis Reference Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma – emphysema Lung emphysema 3 picture Multiple areas of lucency with accenuated of blood vessels at lower lung fields, mainly medially (rectangle) Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma – emphysema Lung emphysema 4 Paraseptal emphysema • Subpleural location • Can coalesce and form bullae, which can rupture and lead to spontaneous pneumothorax HRCT showed multiple air filled rather rectangular shape along the subpleural area, medially (arrow) Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - CCAM Congenital cystic adenomatoid malformation (CCAM)1 or Congenital pulmonary airway malformation (CPAM) - Congenital hamartoma of the developing lung parenchyma and terminal respiratory tract associated with intercommunicating cysts of various sizes. A localized lobar lesion is common without zone preference. Three types of CCAM have been described, based on the cystic size. • Type 1 CCAM, the most common form (about 50% of cases), composed of one or more large cysts (2–10 cm) and sometimes associated with air trapping. • Type 2 CCAM (~ 40%) consist of multiple uniform smaller cysts (0.5–2 cm). • Type 3 CCAM (~10%) appear as large solid masses but have multiple tiny cysts on microscopic examination [25]. CCAMs have communicate with the bronchial tree (unlike pulmonary sequestrations) and the cystic components fill with air within hours or days of birth. Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - CCAM Congenital cystic adenomatoid malformation 2 • The radiologic findings vary with the type of malformation, the number and size of cysts, and the amount of fluid within them. • The most common findings are numerous air-containing cysts with expansion of the ipsilateral hemithorax and contralatearl displacement of the mediastinum. • Occasionally, one cyst may be as large as single large lucent area, similar to congenital lobar hyperinflation. • Almost all cases present in the neonatal period; however, some may present in adulthood when they become infected • Adults with CPAM usually have lower lobe lesions, and the findings at CT can mimic cystic bronchiectasis, intralobar pulmonary sequestration, intrapulmonary bronchogenic cyst, or pneumatocele Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - CCAM CCAM 3 picture CPAM type 1: Note multicystic lesion, vary in size (oval). There is air fluid level in some cysts (arrow). Opacities in the RLL. "Courtest of Dr. Nestor L. Muller, Vancouver BC" Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - LAM Lymphangioleiomyomatosis (LAM) 1 A rare cystic lung disease with unclear etiology affecting almost exclusive women of child-bearing age Characterized by progressive proliferation of smooth muscle in the airways, arterioles, venules, and lymphatic vessels of the lung parenchyma, resulting in progressive shortness of breath, lung cysts, pneumothorax, hemoptysis, and chylous pleural effusion Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - LAM Lymphangioleiomyomatosis (LAM) 2 HRCT scans show multiple small round well-define thin wall cysts that are fairly uniform in size and throughout the lungs [26]. The lung volume in LAM is increased. Air trapping at expiratory CT is not common with LAM unless in severe case that there are multiple cysts instead of identification of the normal lung tissue[26]. Both pathology and imaging findings of LAM can not be differentiated with cystic lung disease of tuberous sclerosis. However, pleural effusion is much common with LAM. Extrathoracic manifestation of LAM are including renal angiomyolipoma, retroperitoneal cystic mass of lymphangioleiomyoma, lymphadenopathy, and chylous ascites[26]. Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - LAM Lymphangioleiomyomatosis (LAM) 3 Thin slice CT image at the carinal level shows rather uniform multiple cysts in both lungs, in severe case. Home How to show Objective Index Definition Causes Causes: lung parenchyma : cystic lung - LAM Lymphangioleiomyomatosis (LAM) 4 In this case, showing classical feature of LAM, left chylous effusion in childbearing aged woman, and multiple small cysts (arrow) Reference Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - LCH Langerhan’s cell histiocytosis 1 LCH – A non-neoplastic proliferation of antigen presenting cells (Langerhans cells) in the lungs that leads to destruction of the lung parenchyma and airflow obstruction Almost all cases of pulmonary LCH are associated with cigarette smoking and more common in Caucasians. Radiologic characteristic findings of LCH includ poorly defined centrilobular nodules, some of which are cavitated, and cysts of varying sizes and shapes with an upper lung predominance Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - LCH Langerhan’s cell histiocytosis 2 In the early stage, chest radiography shows multiple small nodules, which are less than 5 mm in diameter in an upper lung predominance [28]. Cavitary nodules are identified in approximately 10% of cases by HRCT. In advanced disease, a reticulonodular pattern develops and progresses to a coarse reticular pattern Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma : cystic lung - LCH Langerhan’s cell histiocytosis 3 • The most common HRCT findings include cysts and centrilobular nodules with an upper zone predominance • Cysts are usually up to 10 mm in diameter and have bizarre shapes • Relative focal air trapping can be seen in the cystic areas of the lung parenchyma on expiratory CT scans [29] Home How to show Objective Index Definition Causes Causes: lung parenchyma : cystic lung - LCH Langerhan’s cell histiocytosis Note multiple small centrilobular nodules scattering in both upper lung fields with small cysts 4 Reference Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma: Infiltrative disease - Thalassemia Thalassemia 1 • A common inherited disorder of hemoglobin synthesis with varying severity, most common in southeast Asia and Africa. • Pek-Lan Khong et al [30] studied the CT findings of βthalassemia major patients and found that air trapping was the predominant thin-section CT finding in 24%, and patients had reduced FEV 25%-75%. Hepatic iron overload was not a common finding. The relationship between iron deposition in the lungs and pulmonary dysfunction is unclear. Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma: Infiltrative disease - Thalassemia Thalassemia 2 The proposed mechanisms of airway obstruction in βthalassemia include: • Oxidative damage as a result of free iron deposition within the airway epithelium. • Bronchial hyperactivity and chronic immunologic response related to blood transfusion • Disproportionate and/or excessive alveolar growth relative to airway growth caused by hypoxemia or hypoxia, a chronic abnormality in patients with β-thalassemia major. Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma: Infiltrative disease - Thalassemia Thalassemia 3 Case B-thalassemia, thin slice CT scan showed lucency area of air trapping at bilateral posterior basal segment and right anterior basal segment (oval). Note extramedullary hematopoeitic tissue (arrow) Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma: Infiltrative disease - sequestration Intralobar pulmonary sequestration 1 • Pulmonary sequestration - An abnormal development of lung forming a non-function mass that does not directly communicate with the airway and has its own blood supply from a systemic artery (usually a branch of the thoracic or abdominal aorta). Lung sequestrations can be divided into intralobar and extralobar types, based on their relationship to the pleura [25]. • Intralobar sequestration (ILS) is most common in the lower lobes. It lacks its own visceral pleural but has its own systemic arterial supply and drains to the pulmonary veins. • Extralobar sequestration (ELS) has its own pleura and drains through the systemic veins. Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma: Infiltrative disease - sequestration Intralobar pulmonary sequestration 2 • Frequently, ELS occurs on the left (Rokitansky’s lobe) and up to 15% can are within or below the diaphragm • ILS may present in both childhood and adulthood, and, unlike ELS is often detected perinatally. Both ELS and ILS can communicate with the foregut and are sometimes referred to as bronchopulmonary foregut malformations. Communication with the upper gastrointestinal tract is uncommon, but can be shown by barium swallow [25]. • Diagnosis can be made by CT or MRI by demonstrating the origin and course of the anomalous systemic vessel(s) supplying the sequested lung. • Inspiratory and expiration HRCT scans of ILS typically show a non-segmental focal mass, containing soft tissue, and cysts surrounded by low attenuation lung parenchyma (Fig) in a lower lobe. Although, there is no communication between ILS and the tracheobronchial tree, the collateral air-drift and fistula to the bronchi are causes of air-trapping on expiratory HRCT. Home How to show Objective Index Definition Causes Reference Causes: lung parenchyma: Infiltrative disease - sequestration Intralobar pulmonary sequestration 3 CT shows lucent area of air trapping (oval) with feeding artery from the aorta (arrow) Home How to show Objective Index Definition Causes Causes Air trapping from The airway disease • The lung parenchymal disease • The cardiovascular disease Miscellaneous Reference Home How to show Objective Index Definition Causes Causes: Cardiovascular Cardiovascular causes: – Pulmonary Thromboembolism – Pulmonary arterial hypertension Reference Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PE Pulmonary thromboembolism 1 A serious condition that requires proper treatment to reduce morbidity and mortality. CT pulmonary angiography is the most common examination of choice Demonstration of intraluminal filling defect is diagnostic Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PE Pulmonary thromboembolism 2 Air trapping can occur in both acute and chronic pulmonary thromboembolism [31, 32]. There are several proposed mechanisms of bronchoconstriction in acute pulmonary embolism including: • Release of bronchoactive amines such as serotoin and prostaglandins • Change in parasympathetic nervous system tension, which controls the bronchial smooth-muscles [31]. Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PE Pulmonary thromboembolism 3 In chronic PE, regional hyperventilation and low alveolar carbon dioxide tension were suggested as causes of regional bronchoconstriction and air trapping. • Recently, however, more complex mechanisms have been proposed: – – Increase of endothelial-1 and decreased nitric oxide lead to bronchoconstriction and suppress bronchodilatation, respectively [32] Weakness of the bronchial wall due to redirection of blood flow from the bronchial arteries to the ischemic lung and compression of the bronchi by the adjacent deformed pulmonary arteries [32]. Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PE PE 4 Coronal reformatted images show eccentric filling defect of clots in the right lower pulmonary branch (arrow) Relative lucent of mosaic perfusion at the anterior basal segment of RLL (oval) Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PE Pulmonary thromboembolism 5 Multisegmental luncency areas of air trapping in the upper lobes. Note slightly decreased size of the vessels within these lucent areas Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PAH Pulmonary arterial hypertension 1 PAH - condition defined by systolic pulmonary arterial pressure exceeding 30 mmHg of mean pulmonary arterial pressure exceeding 18 mmHg [33]. • Etiologies can be grouped into three major categories: • – Pre-capillary – Capillary – Post-capillary causes Chest radiograph may show markedly enlarged central pulmonary arteries with rapid tapering of the peripheral branches • Other findings depend on cause of PAH Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PAH Pulmonary arterial hypertension 2 • Air trapping is uncommon in PAH • May be seen with – Chronic pulmonary embolism (pre-capillary) – Emphysema (capillary) Home How to show Objective Index Definition Causes Reference Causes: cardiovascular - PAH Pulmonary arterial hypertension 3: Marked enlarged pulmonary trunk (arrow) and heterogeneous attenuation of lung parenchyma. Note low density area of air trapping (oval) PA picture PA Home How to show Objective Index Definition Causes Causes Air trapping from The airway disease • The lung parenchymal disease • The cardiovascular disease Miscellaneous Reference Home How to show Objective Index Definition Causes Reference Causes: Miscellaneous Miscellaneous • Normal variant in the health and normal pulmonary function test • Mimic diseases: Groundglass pattern - PCP, Alveolar proteinosis Home How to show Objective Index Definition Causes Reference Causes: miscellaneous - normal Normal variant in the health and normal pulmonary function test 1 Air trapping, particularly lobular, can be seen in normal adults, and many studies show varying in frequency of air trapping in healthy people with normal pulmonary function test, ranging from 40 to 80% [34]. Webb et al. [35] found that the lingular segments of the LUL are common locations of air trapping in normal adults He postulated that lingular bronchial length and alignment of those bronchi relative to the pleura made them more prone to dynamic compression. Tanaka N. et all [34] studied the frequency of air trapping, overall 64% in asymptomatic subjects with normal pulmonary function test in groups of non smoking and smoking. Air trapping are also seen in both with various degrees and no significant difference between them in the distribution, which is common seen in lower lobes and dependent areas. However, two of non-smoker found air trapping in non dependent lung, while it is not seen in the smoker group. Potential reasons for the high prevalence of air trapping in patients with normal pulmonary function are extensive difference in local lung compliance or muscle tone of small air-ways without small-airway disorder, or presence of a small-airway disorder that is too mild to be detected by percent predicted MEF50% testing. Home How to show Objective Index Definition Causes Reference Causes: miscellaneous - normal Normal variant in the health and normal pulmonary function test 2 Various degrees of air trapping including the lobular, mosaic or extensive type can be observed in subjects with normal pulmonary function. However, most of reports mentioned that lobular air trapping is the most common one. Webb et al [35] suggested that lobular air trapping was caused by regional differences in lung compliance and the phenomenon of interdependence of adjacent lung units: Because of interdependence, a lung region that is less compliant than the lung parenchyma that surrounds it will show relative air retention during expiration, with less of an increase in lung attenuation than that of the surrounding lung. Mastora et al (16) believed that lobular air trapping was never caused by small airway diseases because the frequency of lobular air trapping in their study was not significantly different among smokers, ex-smokers, and nonsmokers. Home How to show Objective Index Definition Causes Reference Causes: miscellaneous - normal Normal variant in the health and normal pulmonary function test 3 HRCT shows mild lucent lingular segment of LUL and RML on expired view. Inspired Expired Home How to show Objective Index Definition Causes Reference Causes: miscellaneous: Mimic diseases - PCP Pneumocystis carinii pneumonia (PCP) 1 • Pneumocystic jiroveci is classified as a primitive fungus and is one of most common causes of pulmonary infection in immunocompromised hosts, espeically those with AIDS. • Ground-glass opacity is the usual finding on CT and often has a patchy or geographic distribution with lower lung predominately. However, the upper lung zone is involved in the severe cases or patients who receive aerosolized pentamidine prophylaxis [36]. Home How to show Objective Index Definition Causes Causes: miscellaneous: Mimic diseases - PCP Pneumocystis carinii pneumonia (PCP) 2 • With progression, lung consolidation develops • Pneumatoceles may develop during the acute phase or during resolution • Less common findings include: – Reticulation and septal thickening – Cavitation – Focal masses – Miliary disease – Pleural effusion – Lymphadenopathy [36] Reference Home How to show Objective Index Definition Causes Reference Causes: miscellaneous: Mimic diseases - PCP Pneumocystis carinii pneumonia (PCP) 3 Thin slice CT chest at the atrial level, there are diffuse groundglass opacities with small left pneumothorax (arrow) Home How to show Objective Index Definition Causes Reference Causes: miscellaneous: Mimic diseases - PCP Pneumocystis carinii pneumonia (PCP) 4 Thin slice CT chest at the aortic arch level, there are diffuse groundglass opacities with interlobular, intralobular septal thickening of crazy paving pattern. No multiple small pneumatocele in both lungs (arrows). Home How to show Objective Index Definition Causes Reference Causes: miscellaneous: Mimic diseases - PAP Pulmonary Alveolar Proteinosis 1 • A condition characterized by accumulation of periodic acidshiff (PAS) staining phopholipid-rich material in the alveoli • Most commonly occurs between 20 and 50 years old. • Dyspnea and nonproductive cough are the most common associated symptoms. Pleuritic chest pain, malaise, and low-grade fever are less common [37]. • Increased incidence of Nocardia infection [38]. Home How to show Objective Index Definition Causes Reference Causes: miscellaneous: Mimic diseases - PAP Pulmonary Alveolar Proteinosis 2 • The classic radiographic findings are a pulmonary edema like pattern with bilaterally, symmetric perihilar ground-glass opacity or consolidation. • HRCT typically shows patchy ground-glass attenuation with superimposed intra- and interlobular septal thickening (crazy-paving pattern) [37]. Home How to show Objective Index Definition Causes Reference Causes: miscellaneous: Mimic diseases - PAP Pulmonary Alveolar Proteinosis 2 HRCT at mid thoracic level, there are bilateral groundglass opacities with inter and intralobular septal thickening (oval). Note relative hypodensity at bilateral subpleural areas, especially RML. Home How to show Objective Index Definition Causes Reference Reference 1 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Webb RW MN, Naidich DP. High resolution CT of the lung, 2nd ed. Philadelphia: Lippincott-Raven Publishers, 1996 Webb RW MN, Naidich DP. Small airway disease. In: Webb WR, ed. High-Resolution CT of the Lung. Philadiaphia: Lippincott Williams & Wilkins, 2001 Stern EJ, White C.S. Hyperlucent lung-bilateral and unilateral. In: Stern EJ, White C.S., ed. Chest radiology companion. Philadelphia: Lippincott Williums&Wilkins, 1999:198-199 Stern EJ, White C.S. Common medical problems. In: Stern EJ, White C.S., ed. 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AJR Am J Roentgenol 2004;182:81-85 Williams HJ, Johnson KJ. Imaging of congenital cystic lung lesions. Paediatr Respir Rev 2002;3:120-127 Pallisa E, Sanz P, Roman A, Majo J, Andreu J, Caceres J. Lymphangioleiomyomatosis: pulmonary and abdominal findings with pathologic correlation. Radiographics 2002;22 Spec No:S185-198 Howarth DM, Gilchrist GS, Mullan BP, Wiseman GA, Edmonson JH, Schomberg PJ. Langerhans cell histiocytosis: diagnosis, natural history, management, and outcome. Cancer 1999;85:2278-2290 Muller NL, Fraser, R.S., Colman, N.C., Pare, P.D. Chronic interstitial lung disease. In: Muller NL, Fraser, R.S., Colman, N.C., Pare, P.D., ed. Radiologic diagnosis of disease of the chest. Philadiaphia: W.B. saunders, 2001:316-368 Stern EJ, Webb WR, Golden JA, Gamsu G. Cystic lung disease associated with eosinophilic granuloma and tuberous sclerosis: air trapping at dynamic ultrafast high-resolution CT. Radiology 1992;182:325-329 Khong PL, Chan GC, Lee SL, et al. Beta-thalassemia major: thin-section CT features and correlation with pulmonary function and iron overload. Radiology 2003;229:507-512 Arakawa H, Kurihara Y, Sasaka K, Nakajima Y, Webb WR. Air trapping on CT of patients with pulmonary embolism. AJR Am J Roentgenol 2002;178:1201-1207 Arakawa H, Stern EJ, Nakamoto T, Fujioka M, Kaneko N, Harasawa H. Chronic pulmonary thromboembolism. Air trapping on computed tomography and correlation with pulmonary function tests. J Comput Assist Tomogr 2003;27:735-742 Collins J SE. Cardiac and congenital lung disease. In: Collins J SE, ed. Chest radiology: The essentials. Philadelphia: Lippincott Williams&Wilkins, 1999:247-264 Tanaka N, Matsumoto T, Miura G, et al. Air trapping at CT: high prevalence in asymptomatic subjects with normal pulmonary function. Radiology 2003;227:776785 Webb WR, Stern EJ, Kanth N, Gamsu G. Dynamic pulmonary CT: findings in healthy adult men. Radiology 1993;186:117-124 Primack SL, Muller NL. High-resolution computed tomography in acute diffuse lung disease in the immunocompromised patient. Radiol Clin North Am 1994;32:731-744 Rossi SE, Erasmus JJ, Volpacchio M, Franquet T, Castiglioni T, McAdams HP. "Crazy-paving" pattern at thin-section CT of the lungs: radiologic-pathologic overview. Radiographics 2003;23:1509-1519 Collins J SE. Alveolar lung disease. In: Collins J SE, ed. Chest radiology: The essentials. Philadelphia: Lippincott Williams&Wilkins, 1999:47-58 Home How to show Objective Index Definition The end Causes Reference
