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Pneumonia, Bronchitis, COVID: How Chest Imaging Helps to Make the Correct Diagnosis

Why an accurate diagnosis is essential in winter.

Autumn and winter bring with them an increase in respiratory infections. Persistent cough, fever, difficulty breathing – the symptoms can seem similar, whether it's a simple viral bronchitis, bacterial pneumonia, or even a complication related to COVID-19.

But what do these symptoms really mean? How can you distinguish a mild infection from severe pneumonia? When does imaging become crucial?

The answer lies in precise chest imaging. A simple X-ray may suffice, but a chest CT scan offers a far more reliable diagnosis – crucial for starting the right treatment at the right time.

In Switzerland, due to seasonal variations, emergency and pulmonology departments see a significant increase in workload between November and March. Rapid and accurate diagnostic imaging can change the patient's journey and accelerate recovery.

Understanding respiratory infections: deceptive similarities

Viral Bronchitis

Viral bronchitis is an inflammation of the bronchi usually caused by viruses (rhinovirus, influenza virus, adenovirus). It is characterized by a productive or dry cough, often persisting for 2 to 3 weeks.

Typical symptoms:

  • Dry or productive cough
  • Slight fever (less than 38.5 °C)
  • Moderate fatigue
  • No severe respiratory difficulties

Imaging: Generally normal or mild bronchial inflammation. A radiograph is often sufficient.

Bacterial Pneumonia

Pneumonia is an infection of the lung tissue (alveoli) usually caused by bacteria such as pneumococcus or Haemophilus. It is more serious than bronchitis and requires antibiotic treatment.

Typical symptoms:

  • Higher fever (38.5-39.5 °C)
  • Productive cough with sometimes colored sputum
  • Shortness of breath
  • Pain when breathing (pleurisy)
  • General signs: fatigue, chills

Imaging findings: Characteristic opacities (consolidations) in the pulmonary areas. X-ray is often sufficient, but CT scans offer greater precision.

COVID-19 and Respiratory Complications

COVID-19 can start as a simple viral infection of the upper respiratory tract, but can progress to severe lung involvement (COVID pneumonia).

Typical presentation:

  • Fever, dry cough, anosmia (loss of smell)
  • In severe cases: shortness of breath, bilateral pneumonia
  • Thromboembolic complications (pulmonary embolisms)

Imaging findings: A characteristic bilateral ground-glass opacity pattern is seen in cases of COVID-19 lung involvement. A chest CT scan is essential to assess severity.

The problem of clinical diagnosis alone

The symptoms of viral bronchitis, bacterial pneumonia, and COVID-19 can overlap considerably. Two patients with the same cough and fever may have entirely different illnesses.

Concrete example: A 65-year-old female patient presents to the emergency room with a fever and cough that has lasted for 5 days. The clinical examination suggests bronchitis. However, she also has mild dyspnea (shortness of breath). Is it viral bronchitis or early pneumonia? Without imaging, the uncertainty remains.

The consequence: Inappropriate treatment, unfavorable outcome, complications. This is where diagnostic imaging becomes crucial.

The role of chest imaging

Chest X-ray: The First Step

Chest X-ray (frontal and lateral views) is the recommended initial imaging for any suspicion of lung infection.

Benefits :

  • Quick (5 minutes)
  • Low radiation
  • Accessible everywhere (doctor's office, emergency room)
  • Moderate cost

Limitations:

  • Moderate sensitivity (70-75%) for detecting early pneumonias
  • Difficult to interpret in cases of obesity
  • Does not always distinguish between bacterial and viral infections
  • Of little use in diagnosing pulmonary embolism

Indication

Suspected classic pneumonia, followed by bronchitis.

Chest CT Scan: The Diagnostic Gold Standard

Chest CT scans (computed tomography) offer infinitely higher resolution, allowing detailed visualization of each lung structure.

Key advantages:

  • Very high sensitivity (95%+) for detecting lung abnormalities
  • Accurate diagnosis of bacterial vs. viral vs. atypical pneumonia
  • Detects complications (pulmonary embolism, pleural effusion, abscess)
  • Assess the severity and extent of the infection
  • Distinguishes bacterial superinfection from a simple viral infection

When to propose it:

  • Suspected severe pneumonia
  • No improvement with antibiotic treatment (suspected atypical pneumonia)
  • Complications: disproportionate shortness of breath, suspected embolism
  • Immunosuppression (risk of opportunistic infection)
  • Suspected COVID with signs of severity
  • Difficult differential diagnosis

Radiation:

The CID Lausanne uses Ultra Low Dose CT technology , which drastically reduces radiation exposure while maintaining optimal diagnostic quality. Ideal for cases where multiple scans may be required.

Classification of patterns in the scanner

Radiologists describe the observed patterns using a standardized classification:

Consolidation opacity: Homogeneous white area, classic sign of bacterial pneumonia. Often unilobar, localized.

Frosted glass pattern: Lighter, diffuse areas of opacity, characteristic of COVID-19 and viral infections. Often bilateral and peripheral.

Reticulated pattern: Fine network of lines, suggesting bronchial or viral inflammation.

Bronchiectasis or bronchitis: Thickening of the bronchial walls, a sign of chronic inflammation or infection.

This classification guides treatment: localized consolidation? Specific antibiotic. Diffuse ground-glass opacities? Monitoring, antiviral treatment if COVID-19 is confirmed.

Differential diagnosis: beyond simple infection

Distinguishing Between Bacterial and Viral Pneumonia

Viral pneumonia (rhinovirus, RSV, parainfluenza) is NOT treated with antibiotics. Administering antibiotics unnecessarily promotes bacterial resistance.

The scanner helps to:

  • Detect typically viral patterns (ground-glass opacities, peripheral distribution)
  • Identify areas of classic bacterial consolidation
  • Recognizing a possible bacterial superinfection of an initially viral pneumonia

Identifying Superinfections

Common case: patient with initial viral pneumonia, partial improvement, then sudden worsening. New fever, productive cough.

Diagnosis: Secondary bacterial superinfection.

The scan shows: New areas of consolidation, often different from the initial viral areas. Urgent need for appropriate antibiotic treatment.

Pulmonary Embolism: A Diagnosis That Can Be Missed

Symptom: Patient with dyspnea, hypoxia, supposedly pneumonia, but almost normal radiograph.

Suspicion: What if it was a pulmonary embolism rather than pneumonia?

A chest CT scan with pulmonary angiography (contrast injection) allows direct visualization of the pulmonary arteries. Thrombosis in these vessels will be immediately visible – a diagnosis impossible with a standard X-ray.

Importance in COVID: Severe COVID patients are at increased risk of pulmonary embolism. A well-performed CT scan can save a life.

Other Differential Diagnoses

  • Pulmonary edema (heart failure): characteristic pattern on CT scan
  • Atelectasis (lung collapse): visible on CT scan
  • Pulmonary mass : detected incidentally, requires follow-up
  • Lung abscess : a serious complication of advanced pneumonia

Winter season: the importance of diagnostic responsiveness

Between November and March, Swiss emergency departments face an overload of respiratory infections. Diagnostic delays lengthen – increasing the risk of adverse outcomes.

Typical case: Patient presented on Monday with cough and fever. X-ray finally performed on Thursday. In the meantime, three days of treatment uncertainty. Pneumonia worsening.

With rapid access to the scanner: Diagnosis on Monday. Treatment begins immediately. Accelerated recovery.

At the CID Lausanne:

  • Chest scan available quickly (priority appointment for suspected pneumonia)
  • Extended hours (6:30am-7:00pm) adapted to emergencies
  • Detailed reports sent directly to the doctor within hours
  • Free transport for patients with mobility difficulties

Key points for patients and professionals

For Patients

If you have a persistent cough, fever, and shortness of breath that lasts for more than 5-7 days, see your doctor promptly. A simple X-ray may be sufficient, but don't be surprised if a CT scan is recommended – this is to ensure an accurate diagnosis and appropriate treatment.

The scan is not "overdiagnosis" – it's an investment in your health quickly.

For Healthcare Professionals

Current recommendations (FOPH, FMH) suggest:

  • Chest X-ray : first line of investigation for suspected pneumonia
  • Chest CT scan: in cases of diagnostic uncertainty, suspected complications, or lack of improvement with treatment
  • CT angiography: if pulmonary embolism is suspected
  • CT follow-up: recommended at 6-8 weeks for severe pneumonia or immunosuppression, to document resolution

Optimization in the COVID era: Low Dose CT allows repetitions without excessive radiation concern – crucial for monitoring.

Conclusion: accurate imaging, effective treatment

In the winter season, with the increase in respiratory infections, rapid and accurate diagnostic imaging is much more than a comfort – it is a medical necessity.

Distinguishing viral bronchitis from bacterial pneumonia, identifying superinfections, excluding pulmonary embolism – these are all challenges where chest imaging is crucial.

CID Lausanne, with its cutting-edge technologies including Ultra Low Dose CT and expertise in thoracic uro-imaging, positions itself as a trusted partner for rapid and reliable diagnosis.

Contact details and next steps

Do you (or your patient) have persistent respiratory symptoms?

For a simple chest X-ray or a complete chest CT scan , contact the CID Lausanne:

Free transportation available.

For professionals: A radiology form is all that's needed. Detailed and fast reports guaranteed.