Thoracic Imaging

Bronchopleural fistula

Abnormal communication between the airway and the pleural space. Caused by rupture of the visceral pleura. Most often 2/2 surgery, however abscess, empyema, and trauma may also result. New or increasing gas in a pleural effusion.

Acute interstitial pneumonia

Acute onset and worst prognosis of all interstitial lung disease. Surfactant destruction. Easy exudative= hyaline membranes, diffuse alveolar infiltration by immune cells, and noncardiogenic pulmonary edema. Chronic organizing= Alveolar wall thickening due to granulation, occurs one week after acute onset.

Panacinar emphysema

Affects the entire acinus throughout the lungs. More severe at the lung bases Alpha 1 antitrypsin deficiency

Angioinvasive Aspergillosis

Aggressive infection characterized by invasion and occlusion of arterioles and smaller pulmonary arteries by fungal hyphae. Almost exclusively in severely immunocompromised patients. CT Halo sign= halo of ground glass attenuation surrounding a consolidation. GG is thought to represent pulmonary hemorrhagic infarction. (Halo sign can also be seen in Wegner, Kaposi, viral infection, hemorrhagic mets. Air crescent sign= Cresent of air from retraction of infarcted lung. Good prognostic sign.

Direct invasion of the central airway by adjacent malignancy

Aggressive laryngeal, thyroid, lung, and esophageal cancer may directly invade the airway.

Cystic lung disease

Air containing lucency with a thin imperceptible wall.

Churg-Strauss Syndrome

Allergic angiitis and granulomatosis Systemic small vessel vasculitis and associated with asthma and peripheral eosinophilia. P-ANCA positive Nonspecific imaging findings. May see peripheral consolidation or ground glass.

Castleman Disease

Angiofollicular lymph node hyperplasia. Localized is usually seen in children and young adults. Surgical excision can be curative. Multicentric usually occurs in older adults in association with AIDS. Often results in systemic illness including anemia, fever, and lymphoma. Typically treated with chemotherapy. Key imaging finding is avidly enhancing lymphadenopathy.

Posterior mediastinum

Anterior border is posterior pericardium and posterior wall of trachea. Posterior border is anterior vertebral body. Contains esophagus, azygous and hemiazygous veins, descending thoracic aorta, thoracic duct, vagus nerves and lymph nodes.

Middle mediastinum

Anterior border is the anterior pericardium and the posterior border is the posterior pericardium and posterior tracheal wall. Contains heart and pericardium, ascending aorta and aortic arch, great vessels, trachea and bronchi, lymph nodes, phrenic nerve, vagus nerve, and recurrent laryngeal nerve.

Pneumonia in the immunocompromised patient

Any of the more common pathogens and atypical organisms including pneumocystis, fungi (aspergillus), Nocardia, CMV, and others.

Aortopulmonary window

Aortic arch forms anterior, superior, and posterior borders. Medial border includes the esophagus, trachea, and left mainstream bronchus. Lateral border formed by the top of the pulmonary artery. Abnormal convexity results from a mass arising from or involving one of the structures of the AP window. Contents include lymph nodes, recurrent laryngeal nerve, left vagus nerve, ligamentum arteriosum, and left bronchial arteries.

Healed tuberculosis

Apical scarring with upper lobe volume loss and superior hilar retraction. Calcified granulomas may be present as well.

Sarcoidosis of the trachea

Appearance ranges from smooth stenosis to nodular and mass like thickening. Posterior membrane of the trachea is not spared.

Airway-invasive aspergillosis

Aspergillus infection deep to the airway epithelial cells. Seen only in immunocompromised. Centrilobular and tree in bud nodules. Indistinguishable from other sources of bronchopneumonia when present.

Hospital acquired pneumonia

Aspiration of colonized secretions. Variety of organisms, but most commonly due to MRSA and resistant gram negative organisms (Pseudomonas).

Central venous catheter

Azygos position increases the risk for venous perforation or thrombus.

Pericardial cyst

Benign cystic lesion, most often located at the right cardiophrenic angle.

Thymolipoma

Benign fat containing lesion with interspersed soft tissue. May become quite large and drape over the anterior mediastinum.

Lymphoma

Both hodgkin and nonhodgkin lymphoma are differential considerations for anterior mediastinal masses. Hodgkin lymphoma commonly involves the thorax including superior mediastinal, prevascular, AP window, and paratracheal nodal levels.

Endobronchial metastases

Breast cancer, renal cell, thyroid, lung, melanoma, and sarcoma are the most common malignancies to metastasize to the central airways.

Single cyst

Bulla= Air filled cyst >1cm. Giant bulla occupies at least 30% of the thorax. Bleb= Cystic structure continuous with the pleura measuring <1cm. Rupture is most common cause of spontaneous pneumothorax Pneumatocele= Air filled space caused by prior trauma or infection.

Pulmonary hypertension associated with hyperemic lung disease (WHO group 3 precapillary)

COPD sleep apnea and interstitial lung disease can result in pulmonary hypertension. Chronic hypoxic vasoconstriction results in vascular remodeling leading to hypertrophy of pulmonary arterial vascular smooth muscle and intimal thickening. Obliteration of pulmonary microvasculature by emphysema or pulmonary fibrosis contributes.

Broncholithiasis

Calcified or ossified material within the bronchial lumen. Often caused by erosion of an adjacent granulomatous lymph node. Nonproductive, cough, hemoptysis, and air trapping.

Pulmonary veno-occlusive disease (who group I post capillary)

Caused by fibrotic obliteration of the venules and pulmonary veins. My be idiopathic or associated with pregnancy, drugs (bleomycin), or bone marrow transplant. Pulmonary arterial enlargement with pulmonary edema and centrilobular ground glass nodules.

Transudative pleural effusion

Caused by systemic or local imbalances in hydrostatic and oncotic forces. Systemic low protein heart failure nephrotic syndrome

Blastomyces Dermatitidis

Central and southeastern US Usually asymptomatic, but may present with flu like illness. Multifocal consolidation, ARDS, or miliary disease may present.

Pulmonary embolism

Central intraluminal pulmonary artery filling defect. Pulmonary emboli typically lodge at bifurcation points. Eccentric circumferential filling defect suggests chronic PE. Wedge shaped consolidation, pleural effusion, and linear bands of subsegmental atelectasis can also be seen.

Lymphoid interstitial pneumonia

Commonly associated with HIV or Sjogren. Diffuse infiltration of the interstitial by lymphocytes and other immune cells with distortion of the alveoli. Diffuse or lower lobe predominant ground glass. Scattered thin walled perivascular cysts. May be complicated by pneumothorax in advanced cases.

Consolidation

Complete filling of the alveoli with a liquid like substance. Pulmonary vessels not visible on non-con CT through a consolidation. Air bronchograms if the airways are patent. Causes silhouetting of adjacent structures on CXR Ddx for acute includes= Pneumonia, ARDS, pulmonary hemorrhage, or edema Ddx for chronic includes= Adenocarcinoma, organizing pneumonia, or eosinophilic pneumonia.

Interlobular septal thickening (smooth)

Conditions that dilate the pulmonary veins. MC cause is pulmonary edema DDx= Pulmonary edema Pulmonary Hemorrhage Atypical infection (esp Pneumocystis Jiroveci Pneumonia)

Saprophytic Aspergillosis

Conglomeration of intertwined aspergillum hyphae and cellular debris making a fungus ball within an existing pulmonary cavity (usu from prior TB or sarcoidosis). Mobile, will change position if patient is imaged in different positions. MC present with hemoptysis. Monod Sign= Air outlining the mycetoma against the wall of the cavity.

Lobar pneumonia

Consolidation of a single lobe. Most common presentation of CAP. Larger bronchi are patent causing air bronchograms.

CAPTAIn Kangaroo has Mounier Kuhn

Cystic fibrosis Allergic bronchopulmonary aspergillosis Post infectious TB/Atypical mycobacteria Aggamaglobulinema Immunodeficiency Kartgener Syndrome Mounier Kuhn

Solitary cavitary lesion

DDx= Primary bronchogenic carcinoma Tuberculosis

Peripheral ground glass or consolidation

DDx= Organizing Pneumonia Chronic eosinophilic pneumonia. Atypical or viral pneumonia Pulmonary edema (tends to be non-cardiogenic)

Diffuse but central predominant GGO

DDx= Pulmonary edema Alveolar hemorrhage Pneumocystis Jiroveci Pneumonia Alveolar proteinosis

Well differentiated adenocarcinoma spectrum (formerly BAC)

Demonstrate lepidic growth (spreading of malignant cells using the alveolar walls as a scaffold for growth). Commonly indolent and negative on PET. Adenomatous hyperplasia= precursor lesion Adenocarcinoma in situ= precursor lesion Minimally invasive adenocarcinoma Adenocarcinoma predominantly invasive with non-mucinous lepidic growth Invasive mucinous adenocarcinoma.

Morgagni Hernia

Diaphragmatic hernia through the foramen of Morgagni Usually occurs on the Right. Anterior mediastinal mass in contact with the diaphragm containing bowel gas is diagnostic for a Morgagni hernia. Mental vessels that can be traced back to the upper abdomen if no bowel gas present on CT.

Lymphangioleiomyomatosis

Diffuse cystic lung disease caused by bronchiolar obstruction and lung destruction due to proliferation of immature smooth muscles in small vessels, lymphatics, and bronchioles. Occurs in 1% of tuberous sclerosis patients. Almost all cases of sporadic LAM are in women of child bearing age. May respond to anti-estrogen therapy Associated with pneumothorax and chylous effusion. CT demonstrates numerous thin walled cysts throughout the lungs.

Miliary tuberculosis

Diffuse random distribution of tiny nodules seen in hematogenously disseminated TB.

Lymphangitic Carcinomatosis

Diffuse spread of neoplasm through the pulmonary lymphatics. Nodular interlobular septal thickening. Usually asymmetric.

Nonspecific interstitial pneumonia

Dry cough and dyspnea Patients age between 40-50 years Thickened alveolar septa from chronic inflammation. Most common pulmonary manifestation of collagen vascular disease. Ground glass opacities differentiate from IPF. Sparing of the immediate subpleural lung. Tends to affect posterior peripheral lower lobes.

Ground glass opacification

Due to either partial filling of the alveoli, alveolar wall thickening, or collapse (atelectasis). Pulmonary vessels are still visible. Acute GGO ddx= edema, pneumonia (more commonly atypical), pulmonary hemorrhage, or ARDS Chronic GGO ddx= Adenocarcinoma, organizing pna, chronic eosinophilic pna (usu upper lobe predominance), idiopathic pneumonias, hypersensitivity pneumonitis, alveolar proteinosis.

Upper lobe predominant fibrotic changes

End stage sarcoidosis End stage silicosis Chronic hypersensitivity pneumonitis

Infectious causes of centrilobular nodules

Endobronchial spread of TB, or atypical mycobacteria Bronchopneumonia Atypical pneumonia (mycoplasma pneumoniae)

Pre-cardiac anterior mediastinal mass

Epicardial fat pad- may simulate cardiomegaly

Empyema Necessitans

Extension of an empyema to a chest wall. MC 2/2 tuberculosis. Nocardia and Actinomyces are other causative agents.

Chronic eosinophilic pneumonia

Extensive alveolar filling and interstitial infiltration with inflammatory eosinophils. Patchy and peripheral upper lobe predominant infiltration. Responds rapidly to steroids.

Round atelectasis

Focal atelectasis with a round morphology. Always associated with an adjacent pleural abnormality. Most common in the posterior lower lobes. 5 diagnostic criteria necessary= adjacent pleura must be abnormal, abnormality must be peripheral and in contact with the pleura, volume loss must be present in the affected lobe, pulmonary vessels and bronchi must be curved .

Fibrous tumor of the pleura

Focal pleural mass not associated with asbestosis or mesothelioma. 20-30% are malignant, so all are excised. Malignancy is based on the number of mitoses seen on pathology. May be associated with hypoglycemia or pulmonary osteoarthropathy. May be pendunculated and often not FDG avid on PET.

Perilymphatic nodules

Follow the anatomic locations of pulmonary lymphatics (sub pleural, peribronchovascular, and septal). DDx= Sarcoidosis= upper lobe predominant. Galaxy sign seen when nodules become confluent. Pneumoconioses= May look identical to sarcoidosis with history of exposure to silicosis, and coal. Lymphangitic carcinomatosis.

Cellular NSIP

GGO without significant fibrotic changes.

Cryptogenic organizing pneumonia

Good prognosis, responds too steroids. Granulation tissue polyps that fill the distal airway and alveoli May be a response to infection, drug reaction or inhalation. CT shows mixed consolidation and ground glass opacities in a peripheral and peribronchovascular distribution. Reverse halo (atoll) sign is relatively specific featuring a central lucently and surrounding GGO.

Adenocarcinoma predominantly invasive with non-mucinous lepidocrocite growth

Ground glass or solid nodule with air bronchogram.

Left lower lobe atelectasis

Heart slightly rotates and the hilum is pulled down. Flat waist sign= flattening of the left heart border due to downward shift of the left hilum.

Squamous cell carcinoma of the airway

Heavily associated with smoking Polypoid intraluminal mass May have irregular, lobulated, or smooth margins Can occasionally invade the esophagus creating a tracheoesophageal fistula.

Lateral meningocele

Herniation of the spinal meninges through an intervertebral foramen or a defect in the vertebral body. Associated with neurofibromatosis.

Mesothelioma

Highly aggressive tumor arising from the pleura. Most cases are due to prior asbestos exposure with a latency of 20 years. Epithelial subtype is most common with a better prognosis than sarcomatoid and mixed subtypes. Nodular concentric pleural thickening with an associated pleural effusion.

Hot tub lung

Hypersensitivity pneumonitis caused by atypical mycobacteria. Centrilobular nodules.

Inflammatory causes of centrilobular nodules

Hypersensitivity pneumonitis= type III hypersensitivity reaction to inhaled organic antigen. Subacute phase predominantly characterized by centrilobular nodules. Respiratory bronchiolitis interstitial lung disease= hypersensitivity reaction to inhaled cigarette smoke mediated by pigmented macrophages. Hot tub lung= hypersensitivity to inhaled mycobacteria. Diffuse panbronchiolitis= chronic inflammatory disorder characterized by lymphoid hyperplasia in the walls of the respiratory bronchioles resulting in bronchiolectasis. Silicosis= inflammatory lung disease that develops as a result of inhaled silica particles. Upper lobe predominant centrilobular and perilymphatic nodules.

Allergic bronchopulmonary aspergillosis

Hypersensitivity reaction to Aspergillus in patients with asthma. Wheezing, low grade fever, cough, and sputum production. CT demonstrates upper lobe predominant bronchiectasis and mucoid impaction (finger in glove sign).

Hypersensitivity Pneumonitis

Hypersensitivity to inhaled organic antigens. Three distinct phases (acute, subacute, and chronic). Acute= Inflammatory exudate filling the alveoli manifesting as nonspecific groundless or consolidation. Small ill defined centrilobular nodules may also be present. Subacute= Centrilobular and ground glass nodules. Mosaic attenuation and GGO can also be seen. Chronic= Upper lobe predominant fibrosis. Findings of subacute disease may be superimposed.

Treatment based on tumor staging

IIB and IIIA, surgery usually performed. IIIB is not resectabl IV not treated with surgery unless adrenal or brain mets

Pulmonary alveolar proteinosis

Idiopathic disease resulting in alveoli filling up with proteinaceous lipid rich material. Resembles pulmonary edem on CXR Crazy Paving on CT= Smooth interlobular septal thickening with areas of patchy geometric ground glass. Susceptible to superimposed infection, particularly Nocardia. Rx is Bronchoalveolar lavage

Basal predominant fibrotic changes

Idiopathic pulmonary fibrosis= Progressive pulmonary fibrosis of unknown etiology. Almost always demonstrates basilar honeycombing. End stage asbestosis= Asbestos induced inflammatory process. Usually other signs of asbestos exposure are present such as pleural plaques. Non-specific interstitial pneumonia= Idiopathic pneumonia, lung injury commonly associated with drug reaction and collagen vascular disease. Honeycombing is usually absent.

Pulmonary hypertension due to left to right shunts (WHO group I precapillary)

Increased blood into the pulmonary arterial bed due to a left to right shunt. Chronically increased flow may lead to vasculopathy and pulmonary hypertension which can lead to reversal of the shunt (Eisenmenger Syndrome). Enlargement of the central and main pulmonary arteries with tapering.

Primary Tuberculosis

Infection from the first exposure to tuberculosis. Often causes adenopathy. Imaging appearance is nonspecific. Four imaging manifestations= Ill defined consolidation Pleural effusion Lymphadenopathy Miliary disease Typical locations are the lower lobes and RML. Ghon Focus= Initial focus of parenchymal infection. Ranke complex= Ghon focus with lymphadenopathy. Cavitation is rare Lymphadenopathy is common= central low attenuation with enhancing rim.

Empyema

Infection within a pleural space. 3 stages in development= Free flowing exudative effusion= Treated with simple needle aspiration or drain. Development of fibrous strands= Large bore chest tube and fibrinolytic therapy. Fluid becomes solid and jelly like= Usually requires surgery. Split pleura sign= Enhancing parietal and visceral pleura of an empyema seen on contrast enhanced study. Split pleura can also be seen with a malignant effusion, s/p talc pleurodesis, fibrothorax, and mesothelioma.

Ventilator associated pneumonia

Infectious agents not present at the time mechanical ventilation was started. Usually polymicrobial and primarily involve gram negative rods (pseudomonas and acinetobacter.).

Round Pneumonia

Infectious mass like opacity seen only in children. MC due to S. pneumoniae. Infection remains confined due to incomplete formation of pores of Kohn.

Interstitial pneumonia

Inflammatory cells located primarily in the interstitial tissue of the alveolar septa causing diffuse or patchy GGO. MC due to viral pneumonia, Mycoplasma, chlamydia, or pneumocystis.

Asbestosis

Inhalation of asbestos fibers. End stage disease can result in fibrosis with a UIP pattern. Predominantly affects the lower lobes Pleural thickening and pleural plaques.

Crazy paving

Interlobular septal thickening with superimposed GGO DDx= Alveolar proteinosis Pneumocystis Jiroveci Pneumonia Organizing Pneumonia Bronchioloalveolar carcinoma Lipoid pneumonia ARDS Pulmonary hemorrhage

Amyloidosis

Irregular narrowing of the airway caused by submucosal deposition of amyloid which may be calcified. Posterior tracheal membrane is not spared.

Pulmonary venous hypertension (who group 2 post capillary)

Left sided cardiovascular disease leading to increase pulmonary venous pressure. Any left sided lesion may results in pulmonary venous hypertension.

Atelectasis

Loss of lung volume due to decreased aeration. Direct signs= displacement of the fissures and crowding of the vasculature. Indirect signs= Elevation of the diaphragm, rib crowding, mediastinal shift toward the side of volume loss, overinflation of adjacent or contralateral lobes, and hilar displacement. Air bronchograms are not seen when there is central bronchial obstruction, but can be seen with sub segmental atelectasis.

Adenoid cystic carcinoma

Low grade malignancy that is not associated with smoking. Perineural and submucosal spread FDG avid, despite indolent growth. Submucosal mass that infiltrates the tracheal wall and surrounding mediastinal fat. May also present as circumferential tracheal or bronchial wall thickening resulting in airway stenosis.

Left upper lobe atelectasis

Luftsichel sign (Air-sickle) Column of air interposed between the aorta and the hyperexpanded superior segment of the LLL.

Pleural metastases

Lung cancer, GI and GU adenocarcinoma, and invasive thymoma can metastasize to the pleura.

Pneumoconioses

Lung disease secondary to inorganic dust inhalation. Silicosis= Inhalation of silica dust. Multiple upper lobe predominant centrilobular and subpleural nodules. Eggshell lymph node calcifications. Can become complicated with large conglomerate masses or pulmonary fibrosis. Increased risk of TB Coal workers pneumoconiosis= Inhalation of coal dust. Centrilobular and subpleural nodules. Can become complicated with large conglomerate masses or pulmonary fibrosis. Increased risk of TB. Caplan Sydnrome= Seen in patients with rheumatoid arthritis and either silicosis or CWP and represents necrobiotic rheumatoid nodules superimposed on smaller centrilobular and and subpleural nodules.

Superior sulcus tumor

Lung tumor occurring in the lung apex Pancoast tumor is a type of superior sulcus tumor with sympathetic ganglia involvement resulting in horner syndrome, ipsilateral ptosis, miosis, and anhidrosis. T3 Tumor

Non-lymphomatous adenopathy

Lymph node calcification, avid enhancement (Castleman Disease, TB, vascular metastases, and sarcoidosis), or low attenuation (think TB, fungal infection, and metastatic disease)are uncommon findings in lymphoma. Egg shell calcification is often found in silicosis, coal workers pneumoconiosis, and sarcoidosis. Dense calcification can be seen in sarcoidosis and prior granulomatous disease.

Multiple lung cysts

Lymphangioleiomyomatosis= a diffuse cystic lung disease caused by proliferation of smooth muscle of the distal airways. Classically associated with chylous effusion. Emphysema= Upper lobe predominant Pulmonary langerhans cell histiocytosis= irregular cysts and nodules, predominantly in the upper lungs. Diffuse cystic bronchiectasis Pneumocystis jiroveci pneumonia= cysts occur in late stage disease. Lymphoid interstitial pneumonia= Alveolar distortion from lymphocytic infiltrate and multiple cysts.

Atypical mycobacteria

M. avium and kansasii are the two most common. Bronchiectasis and tree in bud opacities most often seen in the RML and lingula.

M (TNM staging system)

M0= No mets M1a= local thoracic metastases M1b= distant or extrathoracic metastatic disease

General imaging of pulmonary hypertension

Main pulmonary artery diameter >2.9cm or main pulmonary artery diameter larger than the aortic root. Pulmonary artery calcifications are pathognomonic for chronic pulmonary hypertension. Mosaic attenuation due to perfusion abnormalities and often seen in chronic embolic PAH. Centrilobular ground glass, particularly venoocclusive. Hilum convergence sign describes pulmonary vessels converging on an enlarged pulmonary artery.

Squamous cell carcinoma

Majority arise centrally from main, lobar, segmental bronchi causing symptoms due to obstruction. Lobar atelectasis, mucoid impaction, consolidation and bronchiectasis. Propensity to cavitate.

Thymic carcinoma

Malignant, aggressive and mets hematogenously to the lungs, liver, brain and bone.

Thymic Cyst

May be congenital, secondary to radiation therapy or AIDS. Simple fluid attenuation cyst in the anterior mediastinum.

Primary pulmonary hypertesnsion (WHO group I precapillary)

May be idiopathic or familial Enlargement of the main pulmonary arteries with rapid tapering of peripheral vessels.

Right lower lobe atelectasis

Mirror image of left lower lobe atelectasis Collapsed lower lobe appears as a wedge shaped retrocardiac opacity.

Microscopic polyangiitis

Most common cause of pulmonary hemorrhage with renal failure. P-ANCA positive. Diffuse central predominant ground glass.

Idiopathic pulmonary fibrosis

Most common idiopathic interstitial pneumonia. Dry cough and dyspnea. Age 50 or greater. Interstitial fibroblastic foci with chronic alveolar inflammation (usual interstitial pneumonia). Irregular reticulation in the posterior sub pleural lung bases. In later stages reticulation becomes fibrosis, traction bronchiectasis and subpleural honeycombing.

Thymoma

Most common primary anterior mediastinal mass. Associated with Myasthenia Gravis Often associated with red cell aplasia, hypogammaglobulinemai, paraneoplastic syndrome, and malignancies such as lymphoma and thyroid cancer. Histologically classified as A, AB, B1, B2, B3, and C A= Usually encapsulated. B= Increasing number of epithelial cells (malignant component). C= Thymic carcinoma.

Adenocarcinoma

Most common type of lung cancer. Less commonly associated with smoking than squamous or small cell. Tends to occur peripherally. Presents as a nodule with spiculated margins due to fibrosis. TTF-1 (thyroid transcription factor) is positive in primary lung adeno and negative in metastatic adenocarcinoma.

Tracheal tuberculosis

Most commonly involves the distal trachea and proximal bronchi. Smooth concentric narrowing of a long segment of airway (>3cm).

Wegner Granulomatosis of the Trachea

Most commonly manifests as subglottic tracheal stenosis and circumferential mucosal thickening. Posterior membrane is not spared.

Tree in bud nodules

Multiple small nodules connected by linear branching structures. Linear branching structures represent impacted bronchioles (usu invisible on CT). Nodules represent impacted terminal bronchioles. Almost always associated with small airway infection. DDx= Mycobacteria tuberculosis or atypical mycobacteria Bacterial pneumonia Aspiration pneumonia Airway invasive aspergillosis (seen in immunocompromised patients).

Tracheobronchopathica osteochondroplastica

Multiple submucosal calcified osteocartilaginous nodules along the tracheal wall. Spares the posterior membrane of the trachea

Relapsing Polychondritis

Multisystem disease characterized by inflammation of cartilage. Affects ears, nose, larynx, trachea, joints, and bronchi Airways affected 50% of the time. Middle age women Smooth tracheal bronchial wall thickening with sparing of the posterior tracheal membrane. Increased attenuation ranging from subtle increased attenuation to frank calcification.

N (TNM staging)

N0= no nodal mets N1= Ipsilateral hilar or intrapulmonary lymph nodes N2= Ipsilateral mediastinal lymph nodes N3= Contralateral or supraclavicular lymph nodes on either side.

Pulmonary abscess

Necrosis of the lung parenchyma Typically 2/2 s.aureus, pseudomonas, or anaerobic bacteria. Air fluid levels Spherical with equal dimensions frontal and lateral.

Semi-invasive (chronic necrotizing) aspergillosis

Necrotizing granulomatous inflammation. Seen in debilitated, diabetic, COPD, and alcoholic patients. Cough, chronic fever, hemoptysis. Segmental areas of consolidation, cavitation, and pleural thickening.

Thymic carcinoid

Neural crest origin. 50% are hormonally active. Associated with MEN I and II Indium 111 scan can help differentiate between carcinoma and thymoma.

Small cell carcinoma

Neuroendocrine origin Several paraneoplastic syndromes Strongly associated with smoking. Occur in central bronchi with invasion of the bronchial wall. Large hilar or perihilar mass. Rarely presents as a solitary pulmonary nodule.

Sarcoidosis

Noncaseating granulomas that coalesce to form nodules in masses throughout the body. May cause pulmonary fibrosis with honeycombing predominantly in the mid and upper lung zones (in comparison to IPF). Most common radiographic finding is symmetric adenopathy. Lymph nodes may contain stippled or egg shell calcifications. Most common CT finding is upper lobe predominant perilymphatic nodules of varying sizes. Perilymphatic nodules may coalesce into a mass. Galaxy sign is a mass with surrounding small nodules. Bronchial involvement may cause mosaic attenuation due to air trapping.

Retrosternal clear space

Normal area of lucency posterior to the sternum. Obliteration suggests an anterior mediastinal mass or right ventricular dilation or pulmonary artery enlargement. Increase in retrosternal clear space can be seen in emphysema.

Types of atelectasis

Obstructive= Alveolar gas is absorbed by circulating blood, but is not replaced due to bronchial obstruction. Relaxation= relaxation of lung adjacent to an intrathoracic lesion causing mass effect. Adhesive= due to surfactant deficiency. Cicatricial= volume loss due to architectural distortion of the lung parenchyma by fibrosis.

Solitary pulmonary nodule

Often benign Calcified and solid are more likely to be benign than ground glass, or mixed attenuation nodules. Intralesional fat or popcorn calcification are suggestive of hamartoma. Large size is the most important factor to determine malignancy (0.8-3cm 18% chance). Irregular edge or spiculated margin is suggestive of malignancy. Round shape= malignancy Cavitary or a lesion with small cystic spaces= malignancy.

Histoplasma capsulatum

Ohio and Mississippi River valleys. MC sequela is calcified granuloma Occasionally a pulmonary nodule that can mimic cancer. Chronic infection can mimic TB with fibrocavitary consolidation in the upper lobe. Fibrosing mediastinitis is a rare complication of infection. Lymph nodes can calcify.

Centrilobular nodules

Opacification of the centrilobular bronchiole, or less commonly the artery. Multiple small nodules in the center of the secondary pulmonary lobule.

Pneumocystis Jiroveci Pneumonia

Opportunistic fungi that can cause pneumonia in patients with CD4 of <200. CXR bilateral perihilar opacities with peripheral sparing. CT demonstrates perihilar ground glass with occasional crazy paving. Propensity to cause upper lobe pneumatoceles.

Cryptococcus neoformans

Opportunistic fungus. MC fungal infection in AIDS patients. CD4 <100 Pulmonary infection usually coincides with meningitis. GGO, cavitating nodules, focal consolidation, or miliary disease. Often with lymphadenopathy or effusions.

Carcinoid Tumor

Originate from neuroendocrine cells in the bronchial walls. Endobronchial mass distal to the carina. May present with obstructive atelectasis. 20% present as a pulmonary nodule. Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia= uncommon precursor lesion with multiple foci of neuroendocrine hyperplasia or tumorlets and bronchiolitis obliterans

Benign endobronchial lesion

Papilloma= potentially premalignant and can transform into carcinoma. Followed closely. Single is usually cause by chronic irritation. Multiple papillomas are caused by HPV. Chondroma Schwannoma Hamartoma Leiomyoma Lipoma Adenoma Hemangioma

Extramedullary hematopoiesis

Paraspinal mass that may appear as a posterior mediastinal mass. Occurs in patients with severe congenital anemia (thalassemia and sickle cell). Thought to be a result of herniation of marrow from the vertebrae.

Lobular pneumonia (bronchopneumonia)

Patchy consolidation with poorly defined airspace opacities. Usually involves several lobes MC organism is S. Aureus

Chronic thromboembolic pulmonary hypertension ( WHO group 4 precapillary)

Peripheral eccentric filling defects in the pulmonary vasculature on CTA PE protocol (in comparison to central filling defect in acute PE). Fibrous strands or mosaic attenuation may be present. Corkscrew bronchial arteries that are tortuous and dilated. Bronchial thromboendarterectomy is treatment.

Hampton's hump

Peripheral wedge shaped opacity representing a pulmonary infarct.

Exudative pleural effusion

Pleural disease causing increased capillary permeability. May be caused by pneumonia, empyema, tuberculosis, mesothelioma or pleural metastases, Rheumatoid arthritis or other collagen vascular diseases.

Chylothorax

Pleural effusion consisting of intestinal lymph. MC caused by neoplastic obstruction of the thoracic outlet. Associated with lymphangioleiomyomatosis. Thoracic duct orginates at the cisterna chyli and drains to the subclavian or left brachiocephalic vein.

Health care associated pneumonia

Pneumonia in nursing home residents or in patients with a >2 day hospitalization with in the last 90 days. Pathogens similar to HAP.

Pulmonary hypertension classification

Precapillary= due to pulmonary arterial system or pulmonary arterial blood flow. Chronic alveolar hypoxia is also included. Postcapillary= Problem with pulmonary veins or elevation of pulmonary venous pressure.

Fibrotic NSIP

Predominantly features GGO with fine reticulation and traction bronchiectasis. Honeycombing is usually absent.

Bronchiectasis

Progressive irreversible dilation of cartilage containing bronchi Results from bronchial wall injury due to prior infection or inflammation, bronchial lumen obstruction, or traction due to adjacent fibrosis. Cystic fibrosis Kartagener Recurrent pneumonia Bronchocentric infection= tuberculosis or atypical mycobacteria. Exaggerated immune response= ABPA or vasculitis Impaired immunity= Congenital immunodeficiency, transplant recipients, and agammaglobulinemia. Congenital connective tissue disorder= Mounier Kuhn (tracheobronchomegaly resulting in recurrent pneumonia) and Williams Campbell (disorder of distal bronchial cartilage).

Fibrosing mediastinitis (WHO group 5 post capillary)

Proliferation of fibrous tissue in the mediastinum leading to compression and encasement of mediastinal structure. Most common causes are histoplasmosis and tuberculosis. Increased soft tissue in the mediastinum. Potentially calcified lymph nodes from prior granulomatous infection.

Pulmonary hypertension definition

Pulmonary arterial hypertension is systolic >25mmhg at rest and >30mmhg during exercise. Pulmonary venous hypertension is a wedge pressure of >18mmhg

Desquamative interstitial pneumonia

RB, RB-ILD, and DIP are a continuous spectrum of smoking related lung disease. Brown pigmented macrophages fill the airways and extend into the alveoli. basal predominant patchy or subpleural ground glass opacification. A few cysts may also be present.

Radiation lung injury

Radiation pneumonitis may occur one month following therapy and is most severe 3-4 months following therapy. GGO in the region of the radiation port, although extension outside of the port is common. Radiation fibrosis is the late stage of radiation injury occurring 6-12 months following therapy. Key imaging is fibrosis and traction bronchiectasis in the radiation port.

Tracheal lmyphoma

Rare Usually associated with a mucosa associated lymphoid tissue (MALToma).

Pulmonary gangrene

Rare complication of pneumonia. Extensive necrosis or sloughing or a pulmonary segment or lobe.

Mucoepidermoid carcinoma

Rare tumor originating from tiny salivary glands lining the bronchial tree. Round or oval endobronchial mass that is indistinguishable from carcinoid.

Reactivation post-primary tuberculosis

Reactivation of infection acquired at an earlier age. Cough, low grade fever, hemoptysis, and night sweats. MC in the upper lobe apical segments. Imaging characteristics include upper lobe predominant opacity with cavitation and no adenopathy. Tree in bud opacities suggest endobronchial spread. In immunosuppressed (HIV) low attenuation adenopathy can be seen. Can mimic immune reconstitution syndrome in HIV.

Westermark's sign

Regional oligemia distal to the site of pulmonary thrombus.

Right upper lobe atelectasis

Reverse sign of Golden= Central convex margins of a mass form a reverse S.

Community acquired pneumonia

S. Pneumoniae is the most common cause. Atypical pneumonia typically affects young and otherwise healthy individuals (viral, mycoplasma, and chlamydia). Mycoplasma= varied appearance with potential for consolidation, GGO, centrilobular nodules, and tree-in-bud nodules. Legionella= MC affects older smokers. Peripheral consolidation that ultimately progresses to lobar and multifocal pneumonia. Klebsiella= Occurs in alcoholics and aspirators. Voluminous inflammatory exudates resulting in bulging fissure sign.

Paraspinal lines

Seen lower in the thorax from T8-T12. Paraspinal line distortion may be secondary to a posterior mediastinal mass, hematoma, neurogenic tumor, aortic aneurysm, extra medullary hematopoiesis, esophageal mass, and osteophyte.

Right middle lobe atelectasis

Silhouetting of the right heart border. Anterior wedge shaped opacity on the lateral view.

Centrilobular emphysema

Smoking related disease Upper lobe predominant Affects the center of the secondary pulmonary lobule.

Respiratory bronchiolitis interstitial lung disease

Smoking related interstitial lung disease (symptomatic version of respiratory bronchiolitis). Respiratory bronchiolitis is common in smokers with pigmented macrophages found in respiratory bronchioles. Sheets of macrophages filling the airways with relative sparing of the alveoli. Centrilobular nodules with patchy GGO in a random pattern.

Pulmonary langerhans cell histiocytosis.

Smoking related lung disease. May present as a spontaneous pneumothorax. Most often isolated to the lung, however, lucent bone lesions, diabetes insipidus due to hypophysitis, and skin involvement can occasionally be seen. First detectable abnormality are nodules associated with airways. As the disease progresses the nodules capitate resulting in irregular cysts. Nodules --> cavitary nodules --> irregular cysts CT demonstrates upper lobe predominant cysts and irregular peribronchovascular nodules sparing the costophrenic sulci. Steroid responsive. Smoking cessation critical.

Cocciodes Imitis

Southwestern US Multiple pulmonary nodules, miliary nodules, or multifocal consolidations.

Anterior mediastinum

Space between the sternum and pericardium Contains thymus, lymph nodes, and enlarged thyroid gland. The pericardiac portion of anterior mediastinum is a potential space.

Carcinoid of the airway

Spectrum of neuroendocrine neoplasms Low grade, aggressive, and small cell carcinoma. Endobronchial carcinoid is exceedingly rare in adults, but the most common bronchial tumor in children. Almost always occurs distal to the carina. Endoluminal bronchial mass with avid arterial enhancement. Ddx for enhancing endobronchial mass= mucoepidermoid carcinoma, hemangioma, and glomus tumor.

Paraseptal emphysema

Subpleural and may predispose to pneumothorax

Granulomatosis with polynagiitis (Wegner)

Systemic small vessel vasculitis C-ANCA positive. Classic triad of sinusitis, lung involvement, and renal insufficiency. May cause nasopharyngeal and eustachian tube obstruction in the upper airways. Involvement of the larynx and bronchi is common and may result in airway stenosis. Multiple cavitary nodules that do not respond to antibiotic therapy.

T(tumor) TNM staging

T1= <3cm surrounded by lung or visceral pleura T2= >3 cm and <7cm with invasion into the visceral pleura or endobronchial lesion >2cm from the carina. T3= Tumor >7cm with local invasion of the chest wall, diaphragm, pleura, or superior sulcus. Endobronchial lesion <2cm from carina. T4= Separate tumor nodule in a different lobe in the ipsilateral lung. Or tumor of any size with invasion of mediastinal structures.

Interlobular septal thickening (nodular, asymmetric, irregular)

Tends to be caused by process that affect the interlobular lymphatics MC Lymphangitic carcinomatosis and sarcoidosis

Mucinous Adenocarcinoma

Tends to present with chronic consolidation. CT angiogram sign= especially prominent appearance of enhancing pulmonary vessels within a low attenuation mucin rich consolidation.

Germ Cell Tumor

Teratoma is the most common anterior mediastinal germ cell tumor. Encapsulated, cystic, with fat and calcification. Seminoma is the most common malignant germ cell tumor and most commonly occurs in men.

Cavitary lesion

Thick irregular wall, often with a solid mural component. < 4mm in thickness is often benign. >15mm in thickness, and spiculated margins suggest malignancy.

Right and left paratracheal stripes

Thickening of the paratracheal stripe is most often due to pleural thickening or a tracheal mass. Mediastinal hematoma may cause thickening of the left paratracheal stripe.

Pneumatocele

Thin walled gas filled cyst that may be post-traumatic or develop as sequela of prior infection (s. aureus and pneumocystis). Almost always resolve.

Pulmonary artery catheter

Tip should be in the main, right, or left pulmonary artery. If distal to the interloper pulmonary artery there is increased risk of pseudoaneurysm or pulmonary artery rupture.

Endotracheal tube

Tip should terminate 4-6cm above the carina with the neck in neutral position. In situations of low pulmonary compliance, a lower position may decrease the risk of barotrauma. Direct intubation of the right or left mainstream bronchus may result in complete atelectasis of the non-aerated lung.

Simple pulmonary eosinophilia (Loeffler syndrome).

Transient and migratory areas of focal consolidation. Elevated eosinophil count in peripheral smear. Term simple pulmonary eosinophilia is reserved for idiopathic causes.

Vascular Pedicle

Transverse width of the upper mediastinum. Right border is the border between the SVC and R mainstream bronchus. Left border is the lateral border of the subclavian from the aorta.

Large cell carcinoma

Tumors that are not squamous, adenocarcinoma, or small cell. Strongly associated with smoking. Presents as a large lung mass in the lung periphery.

Multiple cavitary lesions

Typically vascular, or vascular spread Septic emboli Vasculitis Metastases

Pulmonary Edema

Vascular redistribution= First sign of increased pulmonary venous pressure. Increased caliber of the upper lobe vessels compared to the lower lobe vessels. Interstitial Edema= Caused by increased fluid in the pulmonary veins. Indistinct pulmonary vasculature, increased interstitial markings, peribronchial cuffing, kerley A and B lines. Alveolar edema= Filling of the alveoli with fluid. Perihilar opacifications. Pleural effusions and cariomegaly often present.

Anterior Junction Line

Vertical line overlying the upper 2/3 of the sternum. Abnormal convexity or displacement suggests anterior mediastinal mass.

Posterior junction line

Vertical line projecting through the trachea of a frontal radiograph. Seen above clavicles due to vertical extent of lung apices. Abnormal displacement or convexity suggests posterior mediastinal mass or aortic aneurysm.

Fleischner sign

Widening of the pulmonary arteries due to clot.