Imaging of pleural disease
Dr.Hiba Mohammed
Anatomy of pleura
Pleura is a serous membrane
Divided into i
1. Visceral pleura: cover the lung
2. Parietal pleura: cover ribs (costal pleura),diaphragm
(diaphragmatic pleura), mediastinum (mediastinal pleura).
Normal thickness of pleura 0.2-0.4mm and normal pleura is not visible
by any imaging modality unless there is an abnormality
Objectives of the lectures
1. Pleural effusion.
2. Empyema
3. Hemothorax
4. Pneumothorax
5. Hydroneumothorax
6. Tumors of the pleura
Pleural effusion
Pleural effusion is the accumulation of fluid in the pleural space, i.e.
between the visceral and parietal layers of pleura
The fluid may be transude, exudate (pleural effusion), pus (empyema)
,blood (Hemothorax), chyle(chylothorax ) or rarely bile.
Imaging modalities used to detect pleural effusion are
1. X-ray,
2. Ultrasound
3. CT scan
Pleural fluid may be free within the pleural cavity, in which case
the fluid falls to the most dependent portion of pleura.or it may be
loculated due to adhesions
Free pleural effusion on X -ray
1. homogenous opacification with concave upper margin (meniscus sign) on
erect film in the lower zone
2. blunting of costophrenic angle and diaphragm
A massive effusion leads to
complete opacification of the hemithorax
With contralateral mediastinal shift.
CT scan
CT scan is the most sensitive modality for detection of presence of minimal fluid.
It allows distinction between free and loculated fluid showing it’s extend and
localization.
Ultrasound
Normal lung appear nearly isoechoic to liver (same echogenicity)
Pleural fluid appear echofree or anechoic (black) on ultrasound between
the echogenic (white )diaphram and lung tissue
Loculated pleural effusion
Although loculation occurs in all types of effusion, it is a particular
feature of empyema.
Such loculations may either be at the periphery of the lung or within the
fissures between the lobes.
A loculated effusion may simulate a lung tumor on chest radiographs.
There are a number of causes of pleural effusion:
1. Infection.
Pleural effusions due to pneumonia are small .
Large loculated effusions in association with pneumonia
often indicate empyema formation.
In some cases of tuberculosis the effusion is the only visible
abnormality and the effusion may be large.
2. Subphrenic abscess: This is nearly always accompanied by a
pleural effusion.
3. Malignant neoplasm.
Effusions occur with pleural metastases, but it is unusual to
see the pleural deposits themselves on plain chest
radiographs.
Pleural metastases are occasionally seen on CT, MRI or
ultrasound as nodular or mass-like pleural thickening.
Malignant effusions are frequently large.
.
4. Pulmonary infarction.
Pulmonary emboli which result in pulmonary infarction may
cause pleural effusion.
5. Collagen vascular diseases.
common in various collagen vascular diseases.
They may be the only abnormal features on chest imaging.
6. Cardiac failure.
Small bilateral pleural effusions are seen frequently in acute
left ventricular failure.
Larger pleural effusions may be present in longstanding
congestive cardiac failure.
The effusions are usually bilateral, often larger on the right
than the left. Other signs of cardiac failure are usually
visible, such as alteration in the size or shape of the heart,
pulmonary edema or the signs of pulmonary venous
hypertension
7. Nephrotic syndrome, renal failure and ascites are all associated
with pleural effusion.
Empyema
Accumulation of pus in the pleural space or an exudate that contain
organism on gram stain
Causes of empyema
Postinfectious (parapneumonic)
Post-surgical
Post traumatic
Radiographic feature of empyema
On chest X ray ,it is not possible to distinguish clear pleural effusion
from empyema , but when there is loculated fluid ,it is more likely
empyema than effusion.to distinguish empyema from abscess on CHEST
x ray, empyema assume different shape on PA and lateral X ray
On CT scan, empyema appear as
Pleural fluid collection
Thick pleura
Pleural enhancements after IV contrast administration.
Gas in empyema collection may be due to :
Bronchopleural fistula.(common)
Gas-forming organism(rare)
Empyema VS pleural effusion(distinguishing points)
Empyema form obtuse angle with the chest wall
Empyema is Lenticular in shape (biconvex) whereas pleural
effusion crescent in shape (concave toward the lung)
Empyema has enhanced thickened pleura (split pleura sign) on CT
scan, while pleural effusion has imperceptible pleural surfaces.
Sometimes obvious septation in empyema.
Associated consolidation or infection with empyema.
Hemothorax
Accumulation of blood in the pleural space
Causes of hemothorax:
Traumatic (blunt or penetrating trauma).
Spontaneous hemothorax
Malignancy
Anticoagulant
Vascular rupture
It is not possible to distinguish hemothorax from pleural effusion on
conventional chest x ray (same features)
But CT scan can distinguish by measuring density of fluid (blood had
attenuation 35-70 HU).
Pleural calcification
Irregular plaques of calcium may be seen with or without accompanying
pleural thickening.
Unilateral pleural calcification :
Old empyema usually TB.
Old hemothorax.
Bilateral pleural calcification:
often related to asbestos exposure
pneumothorax
Presence of the air within the pleural space.
The majority occur in young people with no recognizable lung disease
(idiopathic).
Occasionally pneumothorax is due to:
emphysema
trauma
interstitial pulmonary disease
pneumocystis carinii pneumonia
Metastases, rarely.
The diagnosis of pneumothorax depends on recognizing:
• Visualization of visceral pleural line
• Absence of vessel shadows outside this line.
Tension pneumothorax
Is pneumothorax with air under pressure in the pleural space.
most common following trauma or mechanical Ventilation
Resulting in one way valve, allowing air to enter the pleural space
and preventing the air from escaping naturally.
Radiological findings of tension pneumothorax on CXR
hyperlucent (black) hemithorax devoid of vascular markings.
collapse of lung on the side of pneumothorax
The diaphragm is depressed.
The mediastinum is pushed to the contralateral side
Hydropneumothorax or hemopneumothorax
If there is fluid and air in the pleural space, it assumes a different shape.
The diagnostic feature is air–fluid level
Pleural thickening (pleural fibrosis or scarring)
Benign pleural thickening less than 3mm in thickness
May follow resolution of a pleural effusion.
Following an asbestos-related pleural effusion.
Nearly always much smaller than the original pleural effusion.
Impossible to distinguish from small pleural effusion on
conventional X –ray
Malignant pleural thickening
Pleural thickening more than 1cm
Circumferential pleural thickening, encasing the lung.
Nodular irregular thickening
Mediastinal pleural involvement.
Involvement of fissure
Pleural based lesion VS. intrapulmonary lesion:
Pleural based lesion forms obtuse angle with the wall and displace
pulmonary vascularity.
Intrapulmonary lesion forms acute angle with the chest wall and engulf
pulmonary vascularity.
Pleural tumors
The commonest pleural tumors are
Pleural metastasis.
Primary pleural tumors, such as mesothelioma
Malignant mesothelioma
Most common primary malignant pleural tumor.
Occur in patient more than 50 years
Associated with asbestos-exposure
Radiographic features
Malignant pleural thickening(as mentioned previously)
Pleural effusion
Small volume hemithorax
Sometimes Pleural calcification
Differential diagnosis of malignant pleural thickening
Pleural metastasis (primary lung cancer, breast cancer).
Malignant mesothelioma
Non-Hodgkin lymphoma.
Invasive thymoma.
