Computed Tomography in Chest Diseases

Dr. Rikin Hasnani

• Developmental Anomalies• Airway Diseases• Pneumonias• Neoplastic diseases• Diffuse Lung Diseases • Disease of mediastinum , Pleura & Chest Wall

Pneumonia

• Streptococcus pnemoniae• Staphylococcus aureus• Haemophilus influenza• Klebsiella • Pseudomonas• Legionella• Tuberculosis

Pneumococcal PneumoniaIt is the most common cause of Pneumonia.• It is more common in male, elderly, during winter or at the end of dry

season, usually following viral infection.• Capsular polysaccharide types 14, 4, 1, 6A/6B, 3, 8, 7F, 23F, and 18C

are the most frequent causes of pneumococcal disease.• Classically, pneumococcal pneumonia produces diffuse involvement

of most of a lobe and more than one lobe may be involved in 10–25% of cases but spread of consolidation throughout an entire lung is unusual.

Imaging • Homogenous non segmental , parrenchymal consolidation involving

one lobe, multi lobar involvement is less common.• More commonly involves lower lobe or posterior segment of upper

lobe.• Minimal volume loss• Air bronchogram is common • Cavitation is rare.• May present as round pneumonia in children• Associated with pleural effusion in 60% cases.

Pneumococcus pneumonia

Staphylococcus aureusX ray• Lobular pattern of bilateral , multifocal, patchy heterogeneous ,

segmental air space consolidation.• Usually lower lobes are involved• Absent air bronchogram.• May progress to homogeneous air space consolidation.• May develop abscess with cavitation.• Cavity has irregular shaggy internal walls and air fluid level.• Pleural effusion in 30 -50 %cases , progress to empyema in 50% cases.

• CT scan• Focal or multifocal masses or nodules, may undergo cavitation• Centrilobular nodules and tree in bud opacities may be present.• Peripheral wedge shaped opacities with associated feeding vessel is

seen in hematogenous dissemination.• Pneumatocele common in children . Responsible for spontaneous

pneumothorax. • Empyema in 20% adult and 75% children

Haemophillus influenza• X ray• Patchy air space opacities – Bronchopneumonia• Lobar consolidation in immunosuppressed.• Reticulonodular opacities associated with consolidation.• Cavitation is rare.• Pleural effusion in 40% cases.• Empyema rare.• Slow resolution of disease.

• Ct scan shows ill defined centrilobular nodules reflecting peribronchial inflammation.

Klebsiella • X ray• Usually involves upper lobe• Homogenous , non segmental lobar consolidation.• Lobar expansion causing bulging fissure sign is seen.• Abscess formation in 50% cases.• Pleural effusion or empyema in 70% cases.

• CT• Necrotizing pneumonia is charecteristic• Consolidation with or without cavitation.• Scattered enhancing linear branching structure representing pulmonary

vessel in atelactic or consolidated lung – CT angiogram sign is seen.• Centripetal resolution (periphery to central) with residual fibrosis is seen. • Cavitation with narrowed or obliterated feeding bronchus impeding

drainage of necrotic lung.• Large vessel thrombosis can be seen .

Pseudomonas• X ray and CT finding varies in bacteremic and Non bacteremic

patients.• Bacteremic patients – patients with systemic toxicity , shock, altered

mental status, non productive sputum.• Non bacteremic pateints – hemodynamically stable with purulent

sputum.

1) Bacteremic ptX ray - pulmonary vascular congestion ->pulmonary edema -> necrotizing bronchopneumonia.• Within 2-3 days mixed alveolar opacities and cavitation may occur.• Mutifocal nodules.• Nodules coalesces to form opacities.

CT scan• Multilobar air space consolidation , upper lobe predilection (82%)• Nodular opacities in 50% cases• May be Centrilobular with tree in bud appearance in 64% cases • Or large randomly distributed nodules in 36% cases.• Ground glass opacity may be seen .• Bronchial wall thickening may be present.• Pleural effusion unilateral in 18% and bilateral in 46% cases

2) Non Bacteremic patients- X ray• Bronchopneumonia pattern • Multifocal , bilateral , nonsegmental consolidation lower lobe more

common. • Abscess , empyema ,pleural effusion - rareCT scan• Reticular or nodular opacities are seen

Legionella• X ray• Patchy , peripheral non segmental consolidation.• Progressing rapidly to other lobes and other lung.• Nodular and mass like consolidation• Cavitation and lymphadenopathy – Unusual.• Pleural effusion 50 -66%• CT• Sharply demarcated peribronchovascular foci of consolidation with

Ground Glass Opacity

• Day 1 Day 2

Day 3

Tuberculosis• Primary tuberculosis-• Consolidation –usually unilateral, dense , homogenous; segmental,

lobar or multifocal . Rapidly progressive cavitary consolidation.• Lymphadenopathy – typically unilateral usually right hilar, or right

paratracheal more common in children.• Atelactasis – usually right sided and usually in children.• Pleural effusion – unilateral and typically self limiting.

• Post Primary Tuberculosis• Consolidation – patchy , heterogenous,involving apical and posterior

segment of upper lobes and superior segment of lower lobes, ill defined borders, satelite nodules.• Cavitation –thin or thick walled, focal or multi focal , air fluid level may be

seen.• Nodular and linear opacities.• Tuberculoma –solitary or multiple pulmonary nodule variable size well

defined or ill defined margins.may exhibit calcification.• Pleural effusion unilateral or bilateral.

• CT• Central low attenuation and peripheral enhancement of affected node• Cavitations are seen• Linear branching opacities and cetrilobular nodules (2-4mm) tree in bud

appearance is seen due to endobronchial spread of disease associated with cavitary disease.• Ill defined nodules (4-8mm)lobular consolidation, thick inerlobular septa.• Milliary nodules (1-3mm) with random distribution , thick nodular

interlobular septa

• Tuberculoma – rim enhancement, calcification, satellite lesion in 80%.• Bronchial narrowing withmural thickening.• Upper lobe predominant bronchiectasis.• Empyema, pleural calcification, bronchopleural fistula – rarely seen

PA chest radiograph of a 9-year-old boy with tuberculosisdemonstrates a coalescent right perihilar consolidationwith ipsilateral hilar and mediastinal lymphadenopathy

Neoplasms

• Solitary Pulmonary Nodule• Adenocarcinoma• Squamous cell Carcinoma• Small Cell Carcinoma• Large Cell Carcinoma• Lymphoma • Metastasis

Solitary Pulmonary Nodule • A solitary pulmonary nodule is defined as a single discrete pulmonary

opacity that is surrounded by normal lung tissue that is not associated with adenopathy or atelectasis. • Diameter of SPN should be less than or equal to 3cm• Incidence 1-2 / 1000 chest X rays

D/D for SPN• Malignant Tumors• Bronchogenic carcinoma (adenocarcinoma, large cell, squamous, small cell), Carcinoid,

Pulmonary lymphoma, Pulmonary sarcoma, Plasmacytoma Solitary metastases (colon, breast, kidney, head and neck, germ cell, sarcoma, thyroid,, melanoma, others)

• Benign Tumors• Hamartoma, Adenoma, Lipoma• Infectious Granulomas• Tuberculosis, Histoplasmosis, Coccidioidomycosis, Mycetoma, Ascaris, Echinococcal cyst,

Dirofilariasis (dog heartworm)• Noninfectious Granulomas• Rheumatoid arthritis, Wegener granulomatosis, Sarcoidosis, Paraffinoma, Others• Miscellaneous• Bronchiolitis obliterans organizing pneumonia, Abscess, Silicosis, Fibrosis/scar,

Hematoma, Pseudotumor, Spherical pneumonia, Pulmonary infarction, Arteriovenous malformation, Bronchogenic cyst, Amyloidoma

Character Benign Malignant

Age Young Old

Smoking history Absent Present

Size of Nodule Small Large

Radiograph density High (Solid) Low (partly solid ,GGO )

Calcification Present – Diffuse , stippled, laminar /concentric or popcorn

Absent or Eccentric

Border Well circumscribed , round Appearance

Lobulated border , Irregular Appearance

Margins Smooth Spiculated

CT volume doubling Time , change in density

Less than 20 days OR more than 400 days

60 – 80 days sq cell carcinoma120 days Adenocarcinoma30 days Small cell carcinoma

• Other features indicating malignancy are• Pleural Retractoins• Feeding vessel (vessel sign)• Vascular convergence• Dilated bronchus leading into nodule • Pseudocavitation & True Cavitation

Types of nodules

Calcification

Benign Nodules

Adenocarcinoma • 4 entity of Adenocarcinoma is identified on CT • 1. Atypical Adenomatous hyperplasia of Lung (<0.5cm)• 2. Adenocarcinoma In Situ (0.5 – 3cm)• 3. Minimally Invasive Adenocarcinoma (<3cm, with invasion <0.5cm)• 4. invasive Adenocarcinoma

Squamous Cell Carcinoma• Squamous cell carcinoma is defined as a malignant epithelial tumor

showing keratinization and/or intercellular bridges.• It has rapid local growth and relatively late distant metastases.

Imaging • Frequent secondary atelectasis (absent air bronchograms),

obstructive pneumonia, or mucoid impaction; may be dominant radiologic abnormalities • Central mass • Bronchial wall thickening; thickened (>3 mm) intermediate stem line

(i.e., posterior wall of the bronchus intermedius) (lateral radiography) • Peripheral lung nodule or mass • Cavitation • Lymphadenopathy

CT chest• Irregular central mass with abrupt obstruction of bronchial lumen • Post-obstructive consolidation , atelectasis ; contrast administration

may help differentiate tumor from adjacent consolidation and atelectasis , as tumor typically enhances less than atelectatic lung • Bronchial wall thickening • Peripheral mass or nodule • Cavitation• Lymphadenopathy

Drowned Lung

Small Cell Carcinoma • Small-cell carcinoma is a malignant epithelial tumor consisting of

small cells with scant cytoplasm, ill-defined cell borders, finely granular nuclear chromatin, and absent or inconspicuous nucleoli.

Chest X ray• Central mass • Lymphadenopathy• Peripheral nodule rarely.

Large cell carcinoma• Large-cell neuroendocrine carcinoma is defined as “a large-cell

carcinoma showing histologic features such as organoid nesting, trabecular, rosette-like and palisading patterns that suggest neuroendocrine differentiation and in which the latter can be confirmed by immunohistochemistry or electron microscopy.• It is an aggressive cell type of lung cancer that accounts for

approximately 9% of all lung carcinomas. • These neoplasms are characterized by rapid growth and frequent

metastases at presentation.

Lymphoma • Focal or multi-focal nodules, masses, or consolidations• Ground glass opacities, CT halo sign• Air bronchograms (90%) ; bronchial stretching, narrowing or

dilatation; bubble-like lucencies; cavitation• Reticular opacities• Pleural effusion in up to 10% of cases• Lymphadenopathy in 5–30% of cases

Metastasis • Bilateral multifocal well-defined nodules/masses; spherical morphology • Variable size• Multi-focal opacities with ill-defined borders; may mimic air space disease • Most numerous in the lower lobes • May exhibit associated hilar/mediastinal lymphadenopathy • May exhibit associated pleural effusion • Rarely ◦ Cavitation, ◦ Calcification ◦ Solitary nodule/mass ◦ Endobronchial

lesion; may exhibit atelectasis/consolidation ◦ Lymphangitic carcinomatosis

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