Description of above image:
- Lateral chest radiograph shows small bilateral pleural effusions. Enlarged cardiac silhouette with abnormal bands of density noted anterior to the heart (between arrows). Of note, this band of density consists of a central soft tissue sandwiched by lucent stripes.
Key Facts about pericardial effusions:
- Pericardial effusion can be transudate or exudate (pus, blood, infection)
- Pericardial effusion refers to the accumulation of excess fluid within the pericardium, the sac surrounding the heart. This can occur due to various underlying causes, such as infections, autoimmune disorders, or trauma.
- Symptoms depend on the size and rate of accumulation of effusion
- Chest radiography is not diagnostic of pericardial effusion in most cases
- Ultrasound, CT and MRI used to assess size and extent of pericardial effusion
- Measurement of pericardial effusion by CT/MRI tends to be larger than in echocardiography
Imaging modalities such as echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) and X-Ray can be used to visualize and diagnose pericardial effusion. Here is a summary of the findings that may be observed on each modality:
Radiographic Signs of Pericardial Effusion
- All four signs are sensitive (71-100%) but not specific (12-46%).
- Enlarged cardiac silhouette with sharp margin, “water bottle” silhouette
- Pericardial fat stripe (separation of pericardial layers)
- Predominantly left-sided pleural effusion
- Increased transverse cardiac diameter compared with previous radiograph
- Pericardial effusion may cause an enlargement of the silhouette of the heart on a chest X-ray, resulting in a “water bottle” appearance.
- The presence of pericardial effusion may also cause an elevation of the diaphragm on the affected side, resulting in a “double diaphragm” appearance.
- However, it is important to note that chest X-ray has limited sensitivity for detecting pericardial effusion, and other imaging modalities such as echocardiography or CT may be more accurate in detecting and evaluating this condition.
Echocardiography:
- Pericardial effusion may appear as an anechoic (dark) area surrounding the heart on echocardiography.
- The thickness of the pericardial fluid layer can be measured and is typically expressed in millimeters. A thickness of more than 4 mm is considered abnormal.
- The presence of pericardial effusion may also cause changes in the size and shape of the heart, as well as alteration in the movement of the heart wall.
Computed Tomography (CT):
- Pericardial effusion may appear as a fluid-filled space surrounding the heart on CT images.
- The size and location of the effusion can be accurately measured on CT.
- CT may also be able to identify the underlying cause of the effusion, such as a mass or tumor.
Magnetic Resonance Imaging (MRI):
- Pericardial effusion may appear as a fluid-filled space surrounding the heart on MRI images.
- The size and location of the effusion can be accurately measured on MRI.
- MRI may also be able to identify the underlying cause of the effusion, such as inflammation or scarring of the pericardium.
It is important to note that the choice of imaging modality will depend on the specific clinical presentation and the availability of the equipment. Echocardiography is often the initial imaging modality used to evaluate pericardial effusion, but CT or MRI may be used for further evaluation or if the effusion is large or complex.
These images were contributed to this radiology teaching file courtesy of our radRounds Partner, RadiologyinThai.com.
