Mediastinitis

Mediastinitis is a serious inflammatory condition affecting the mediastinum, the area in the middle of the chest between the lungs. This space contains vital structures including the heart, major blood vessels, trachea, esophagus, thymus, and lymph nodes. When infection or inflammation develops in this area, it can quickly become life-threatening and requires prompt medical attention. Radiological imaging plays an important role in diagnosing and monitoring this condition.

What Causes Mediastinitis?

Mediastinitis can develop through several different mechanisms. The most common causes include:

• Complications following cardiac or thoracic surgery
• Perforation of the esophagus
• Infections that spread from adjacent areas like the neck or lungs
• Trauma to the chest
• Descending infections from dental or throat procedures

Imaging tests help radiologists identify not just the presence of mediastinitis but often its underlying cause as well.

How Mediastinitis Appears on Chest X-rays

Chest X-rays are typically the first imaging study performed when mediastinitis is suspected. On X-rays, radiologists look for:

• Widening of the mediastinum
• Air within the mediastinal space
• Fluid collections
• Loss of normal mediastinal contours
• Pneumomediastinum (air in the mediastinum)

Chest X-rays can suggest mediastinitis, but often lack the detail necessary to make a definitive diagnosis.  Usually a CT scan is needed for a more confident diagnosis.

CT Scan Findings in Mediastinitis

Computed tomography (CT) is the best test for diagnosing mediastinitis. A CT scan provides detailed cross-sectional images that can reveal:

• Mediastinal fat stranding (streaky appearance of fat due to inflammation)
• Fluid collections or abscesses
• Gas bubbles within the mediastinum
• Thickening of the mediastinal fascia
• Evidence of the underlying cause (such as esophageal perforation)

CT scans with intravenous contrast are particularly valuable as they can highlight areas of inflammation and show fluid collections. This imaging modality also guides potential interventions such as drainage procedures.

MRI Evaluation of Mediastinitis

While CT is most commonly used, Magnetic Resonance Imaging (MRI) sometimes plays a role in evaluating mediastinitis, particularly in:

• Patients with contraindications to CT contrast
• Cases requiring better soft tissue delineation
• Chronic mediastinitis evaluation
• Assessment of complications involving the spine or neural structures

MRI shows excellent soft tissue contrast and can be helpful in distinguishing inflammation from fibrosis in cases of chronic mediastinitis.

Acute vs. Chronic Mediastinitis: Imaging Differences

Radiologists distinguish between acute and chronic forms of mediastinitis based on specific imaging characteristics:

Acute Mediastinitis Imaging Features

• Fluid collections with enhancing rims
• Air-fluid levels
• Inflammatory stranding of mediastinal fat
• Rapid changes between serial imaging studies

Chronic Mediastinitis Imaging Features

• Fibrosis and calcification
• Inflammation in the mediastinum
• Enlarged lymph nodes
• Narrowing of major vessels
• Stable appearance over time

The distinction is important as treatment approaches differ between acute and chronic presentations.

Complications Visible on Imaging

Advanced imaging can reveal potentially life-threatening complications of mediastinitis, including:

• Mediastinal abscesses
• Pericardial effusion or tamponade
• Pleural effusions
• Vascular complications (such as pseudoaneurysms)
• Airway compression

Identifying these complications early through imaging studies is important for proper management and improved patient outcomes.

Follow-up Imaging in Mediastinitis

After initial diagnosis and treatment, follow-up imaging helps monitor the response to therapy. Radiologists typically note progressive resolution of inflammatory changes and decreasing size of fluid collections when treatment is effective. Persistent or worsening findings may indicate treatment failure or development of complications requiring additional interventions.

When to Suspect Mediastinitis Beyond Imaging

While imaging findings are important for diagnosis, clinical correlation remains essential. Radiologists should suggest mediastinitis when imaging findings correlate with:

• Recent cardiac or thoracic surgery
• History of esophageal procedures
• Unexplained chest pain and fever
• Elevated inflammatory markers

The combination of clinical history, laboratory findings, and imaging features provides the most accurate diagnosis.

Conclusion

Mediastinitis represents a serious medical condition that requires prompt diagnosis and treatment.  Imaging with CT scans plays an important role in diagnosing this condition, identifying its cause, detecting complications, and monitoring treatment response.

Diagnosing mediastinitis promptly helps doctors initiate appropriate management strategies quickly, potentially saving lives. For patients seeing this term on their radiology reports, it means there is a condition requiring immediate medical attention and likely specialist consultation with thoracic surgeons or infectious disease specialists.

References

1. https://my.clevelandclinic.org/health/diseases/24295-mediastinitis
2. https://www.ncbi.nlm.nih.gov/books/NBK559266/
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC1312210/