Congenital anomalies: cysts, defects, and diverticula
Pericardial cysts (pericardial cysts) are the most common benign lesions of the pericardium, although they are generally rare. They are typically located in the cardiophrenic angles, more often on the right. As a rule, they are asymptomatic and found incidentally. Morphologically, they are thin-walled, septation-free lesions attached to the pericardium.
- Radiography: bulging of the cardiac contour in the right cardiophrenic angle.
- CT: well-defined fluid-attenuation lesion with no contrast enhancement. The shape may change with respiration.
- MRI: low signal on T1-weighted images (can be high if protein is present) and high on T2-weighted images. No contrast enhancement.
Pericardial defects can be complete or partial (the latter being more common). They result from embryogenesis disorders and may be associated with other malformations (Tetralogy of Fallot, bronchogenic cysts). The main danger is herniation (herniation) of the heart or left lung, which can lead to incarceration and infarction of the left atrial appendage.
Pericardial diverticulum is a rare outpouching of the serous layer through a defect in the fibrous layer. It is usually located on the right and tends to grow. On CT, it appears as a water-density lesion.
Pericardial effusion and tamponade
Pericardial effusion (pericardial effusion) is the accumulation of more than 50 ml of fluid in the pericardial cavity. Causes are diverse: heart failure, infections, tumors.
- Echocardiography: the primary method. Small effusion is visible posterior to the left ventricle, moderate and large effusion surrounds the heart. The disadvantage is the inability to distinguish transudate from exudate.
- Radiography: informative when the volume is 200 ml or more (water-bottle heart shape).
- CT and MRI: more accurately assess size and extent, especially in loculated effusions (distance between layers > 4 mm).
Acute and abundant fluid accumulation leads to cardiac tamponade (cardiac tamponade). Fluid compresses the chambers, limits their filling, and reduces cardiac output. Echocardiographic signs include right atrial compression and diastolic collapse of the right ventricle.
Pericardial tumors
Tumor involvement is often accompanied by abundant hemorrhagic effusion. Contact invasion from adjacent structures (e.g., in mediastinal tumors) is frequently observed, manifesting as a disruption of the pericardial contour.
Some specific tumors have a characteristic imaging appearance:
- Lipoma: low attenuation on CT, high signal on T1 and T2 MRI.
- Melanoma (metastases): high signal on T1-weighted images due to melanin.
- Teratoma: contains calcifications or fat.
- Fibroma: low signal on T2-weighted images.
Important: imaging methods determine localization and boundaries, but biopsy remains the "gold standard" of diagnosis.
Briefly: answers to topical questions
What causes pericardial effusion?
Pericardial effusion (pericardial effusion) is caused by various systemic, infectious, and neoplastic processes. The main causes include:
- Heart failure — leads to fluid accumulation.
- Renal or hepatic failure — systemic metabolic disorders.
- Infections — bacterial, viral, and fungal infections.
- Neoplastic processes — lung cancer, breast cancer, lymphoma.
Effusion can also occur against the background of acute pericardial inflammation caused by myocardial infarction, mediastinal irradiation, connective tissue diseases, or uremia.
What echocardiographic signs are characteristic of cardiac tamponade?
Cardiac tamponade (cardiac tamponade) is characterized by specific echocardiographic signs reflecting chamber compression and hemodynamic impairment. The main manifestations include:
- Right atrial compression — compression of the chamber from the outside.
- Diastolic collapse of the RV free wall — a typical sign that may be absent in right ventricular hypertrophy and pulmonary hypertension.
- Increased respiratory variability — assessed at the mitral and tricuspid valves.
- Blood flow impairment — changes in diastolic flow velocity and abnormal right-sided venous flow.
- Changes in the inferior vena cava — reduced inspiratory collapse.
What is the normal thickness of the pericardial layers according to CT and MRI?
The normal thickness of the pericardial layers on computed tomography and magnetic resonance imaging is less than 2 mm. An increase in this parameter indicates pathology. For example, visualization of a thickened pericardium measuring 4 mm or more is the main diagnostic criterion for constrictive pericarditis (constrictive pericarditis) when differentiating from restrictive cardiomyopathy.
How to differentiate transudate and exudate in the pericardial cavity using CT?
Differential diagnosis of transudate and exudate in the pericardial cavity on CT is based on the evaluation of fluid X-ray attenuation.
| Characteristic | Transudate | Exudate |
|---|---|---|
| X-ray attenuation | Low attenuation (0–20 HU) | Higher attenuation (up to 50 HU and more) |
| Typical composition | Simple fluid | Purulent exudate or hemopericardium |
In the presence of hemorrhage or purulent contents, effusion attenuation increases, allowing it to be distinguished from protein-poor transudate.
Class and exam questions
Where are pericardial cysts most commonly localized?
In most cases, they are located in the cardiophrenic angles, predominantly on the right side.
At what volume does pericardial effusion become visible on a radiograph?
Chest radiography becomes informative when there is at least 200 ml of fluid in the pericardial cavity.
What is the danger of pericardial defects?
Herniation of the heart or lung can occur through defects, which, if incarcerated, can lead to coronary artery compression or left atrial appendage infarction.
What else to study on this topic
- Differential diagnosis of pericardial cysts and mediastinal cysts
- Quantitative evaluation of effusion using CT and MRI
- Imaging features of partial pericardial agenesis
- The role of T1 and T2 mapping in the diagnosis of myocardial and pericardial pathologies
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Pericardial diseases" and 2,199 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the «Chest Radiology» section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.