Ventilation scintigraphy of the lungs

A practical guide for referring physicians

Principle and method

Ventilation scintigraphy of the lungs is a functional radionuclide method that allows regional lung ventilation to be visualised and correlated with perfusion. Its main benefit lies in its combination with perfusion scintigraphy (known as a V/Q scan), which provides essential information about the ventilation/perfusion ratio and is the basic method for diagnosing pulmonary embolism (PE).

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Radiopharmaceuticals used for ventilation studies:

  • 81mKr (krypton) – an inert gas, ideal for continuous inhalation, has a short half-life (13 s) but limited availability.

Imaging is performed planarly in several projections, but increasingly using SPECT/CT, which allows three-dimensional evaluation and fusion with CT images.

Main clinical indications

1. Diagnosis of pulmonary embolism (PE)

  • In combination with perfusion scintigraphy, ventilation scanning is a standard and validated method for detecting PE.
  • A mismatch of perfusion defect (normal ventilation but impaired perfusion) is a typical picture of acute embolisation.
  • Conversely, matched defects (impaired ventilation and perfusion) are more indicative of other pulmonary pathologies (e.g. COPD, pneumonia, tumour).

2. Preoperative examination in thoracic surgery

  • Quantification of regional ventilation before planned resection (lobectomy, pneumonectomy).
  • Enables prediction of postoperative function and risk of respiratory insufficiency.

3. Chronic obstructive pulmonary disease (COPD) and asthma

  • Evaluation of ventilation distribution, assessment of the degree and distribution of ventilation disorders.
  • Use in differential diagnosis to distinguish between restrictive and obstructive disorders.

4. Interstitial and other lung diseases

  • Ventilation scintigraphy can document irregularities and provide a supplement to HRCT or MRI.

5. Transplant medicine

  • Assessment of regional lung function in donors and recipients, monitoring of graft function.

Interpretation 

Positive findings

  • Mismatch – preserved ventilation, impaired perfusion → typical for PE.
  • Matched defect – ventilation and perfusion reduced to the same extent → chronic or structural lung disease.
  • Diffuse ventilation disorders – typical in COPD, emphysema or severe asthma.

Practical information for the referring physician

  • Patient preparation: no preparation required; the patient must be able to cooperate during inhalation.
  • Examination procedure:
    • inhalation of radiopharmaceutical (gas or aerosol),
    • imaging in several projections (planar or SPECT/CT),
    • followed by perfusion scintigraphy for correlation.
  • Examination duration: 20–40 minutes (ventilation + perfusion).
  • Radiation exposure: very low (ventilation component approx. 0.2–1 mSv, total V/Q examination 1.5–3 mSv).
  • Contraindications: relative – patients unable to cooperate during inhalation.

Summary for practice

Ventilation scintigraphy of the lungs is:

  • a key method in combination with perfusion scintigraphy for the diagnosis of PE,
  • essential in planning lung surgery,
  • valuable in the evaluation of ventilation disorders in COPD, asthma and interstitial diseases,
  • safe, with minimal radiation exposure and a wide range of clinical indications.

Together with the perfusion part (V/Q scan), it is one of the most sensitive methods for detecting pulmonary embolism and significantly complements modern imaging algorithms.