BACTERIAL PNEUMONIA IMAGING

DR. DEV LAKHERA

Imaging modalities used Radiographic patterns Specific causes and their

findings Complications of pneumonia

Bacterial pneumonia

Imaging modalities used CHEST RADIOGRAPH1. PRESENCE 2. LOCATION AND EXTENT3. MONITOR RESPONSE TO THERAPY 4. DETECT COMPLICATIONS

COMPUTED TOMOGRAPH1. SUBTLE ABNORMALITIES2. TO RULE OUT ALTERNATIVE DISEASE PROCESS IN PATIENTS WITH PERSISTANT OR

RECCURENT PNEUMONIAS

RADIOGRAPHIC PATTERNS OF PNUEMONIAS

1. LOBAR PNEUMONIA2. BRONCHOPNEUMONIA3. SPHERICAL OR ROUND

PNEUMONIA4. INTERSTITAL PNEUMONIA

Lobar pneumonia

Begins in the distal air spaces/ acini as an inflammatory exudate

Characteristic appearance

Homogenous non segmental consolidation.

Lung volume is retained. Exudate may be affected by

gravity

loss of silhouette sign

CT APPEARANCE

Round pneumonia Rounded lesion with ill defined

marginsMore common in childrenLooks like a mass lesion

Bronchopneumonia Affects the mucosal

surface of bronchi and bronchioles.

Peribronchiolar focus of infection.

Inhomogeneous patchy, poorly defined opacities

CT appearance

Bilateral peribronchial dense infiltrations

Centrilobular nodules in a patient with bronchopneumonia

Tree-in-bud sign

Tree-in-bud sign is an imaging finding that implies impaction within bronchioles

Specific causes and their findings

Lobar type Pneumococcus Klebsiella Legionella Chlamydia Moraxella Nocardia Actinomycetes

Streptococcus pneumonia

Responsible for most of the cases of community acquired pneumonia.

Associated small pleural effusion may be seen. Cavitation and empyema is rare.

Pneumococcal pneumonia involving the entire left lung

radiographic manifestations may vary

Associated complication

Pleural effusion Empyema and

cavitation are rare features

Klebsiella pneumoniae

0.5-5 % of all the cases of pneumonia Higher prevalence in older patients with alcoholism and

debilitated hospitalized patients

Bulging fissure sign

Voluminous exudates causing lobar expansion

75-year-old man with alcoholism and Klebsiella pneumonia

Legionella Pneumophila

Legionella contaminates water systems, such as air conditioners and condensers.

Affects smokers and debilitated

Radiologically

Spreading consolidation Small effusions Slow resolution

Actinomyces sp

Ability to spread across fascial planes to contiguous tissues without regard to normal anatomic barriers

Seen in immunocompromised people

On CT, parenchymal actinomycosis is characterized by airspace consolidation.

Central areas of low attenuation

Adjacent pleural thickening

BRONCHOPNEUMONIC APPEARANCE

Staphylococcus aureus Pseudomonas aeruginosaHemophilus influenzaAnaerobic organisms E.coli

STAPH AUREUS Seen in patients in chronically ill patients in hospital setting. Follows aspiration from upper respiratory tract. Rarely hematogenous.

Features

Rapid spread Volume loss Pneumatoceles Empyema and abscess

formation

PSEUDOMONAS AEROGINOSA

confluent bronchopneumonia that is often extensive and frequently cavitates

Haemophilus Pneumoniae

Found in sputum in association with chronic lung diseases like bronchitis and bronchiectasis

They have no characteristic radiographic appearance(widespread and bronchopneumonic).

ANAEROBIC PNEUMONIAS

Associated with aspiration Common organisms: Bacteroids, clostridium and

peptostreptococcus.

STANDING POSITION SUPINE POSTION

POSTEROBASAL SEGMENTOF LOWER LOBE

POSTERIOR SEGMENT OF UPPER LOBE

Anaerobic lung abscess in an alcoholic patient with poor oro-dental hygiene

Complications of pneumonia

Lung abscess Pneumatocele Bronchiectasis Empyema Bronchopleural fistula Pulmonary gangreane Septic emboli

LUNG ABSCESS Lung abscess is defined as a localized necrotic cavity containing pus

PRIMARY SECONDARY

• Seen after pneumonia.

• -They most commonly arise from aspiration , necrotizing pneumonia or chronic pneumonia

• -More with staphylococcus , Klebsiella

• Bronchogenic carcinoma , inhaled foreign body 

• Hematogeneous spread: bacterial endocarditis

• Direct extension from adjacent infection : mediastinum , subphrenic

On CT the wall of the abscess is typically thick and the luminal surface irregular , enhance with contrast

Pneumatoceles

thin-walled, gas-filled space that usually develops in association with infection.

It presumably results from drainage of a focus of necrotic lung parenchyma

Feeding vessel sign Direct vessel leading

up to the opacity

Septic emboli cardiac valves (endocarditis), peripheral veins (thrombophlebitis) venous catheter

Mutiple nodules with cavitation

Empyema

Streptococcus pyogenes and S. aureus. Radiographically, early signs include obliteration of the

costophrenic angle 2-5% of pulmonary infections

Fungal Infections

Endemic human mycoses

Opportunistic mycoses

1-Histoplasmosis2-Coccidioidomycosis3-Blastomycosis

1-Aspergillosis2-Candidiasis3-Cryptococcosis4-Mucormycosis

Allergic Bronchopulmonary Aspergillosis (ABPA)

a) Etiologyb) Clinical Picturec) Radiographic Features

a) Etiology :-ABPA represents a complex hypersensitivity

reaction (type 1) to Aspergillus occurring almost exclusively in patients with asthma and occasionally cystic fibrosis

Radiographic Features :

Plain Radiography :

-Transient patchy areas of consolidation may be evident representing eosinophilic pneumonia

-Eventually bronchiectasis may be evident

Finger like projections from hilum from bronchial mucoid impaction

Glove finger sign

CT :

--Fleeting pulmonary alveolar opacities (common manifestation)

--Central upper lobe saccular bronchiectasis (hallmark)

--Bronchial wall thickening (common)--Cavitation , 10%

Gloved finger appearance

INVASIVE ASPERGIOLSIS

Halo signAir crescent sign

HISTOPLASMOSIS

Cause –Inhalation of soil contaminated by bird excreta

Radiographic picture resembles tuberculosis

THANK YOU