Lung Perfusion/Ventilation Scan (V/Q Scan)

Lung Perfusion/Ventilation Scan (V/Q Scan) – Details & Precautions

A Lung Perfusion/Ventilation (V/Q) Scan is a nuclear medicine test used to evaluate lung function and detect blood flow or airflow abnormalities. It is primarily used to diagnose pulmonary embolism (PE) (a blood clot in the lungs) and assess conditions like chronic obstructive pulmonary disease (COPD) or lung infections.

Details of a Lung Perfusion/Ventilation Scan

Purpose

• Detects pulmonary embolism (PE) (blood clots in the lungs).
• Evaluates lung blood flow (perfusion) and airflow (ventilation).
• Assesses lung function before lung surgery or transplantation.
• Diagnoses chronic lung diseases (e.g., COPD, emphysema).

Types of V/Q Scan

1. Ventilation Scan (Airflow Test)

   • You inhale a small amount of radioactive gas/aerosol (e.g., Xenon-133 or Technetium-99m DTPA).
   • A gamma camera takes images of how well air moves through the lungs.

2. Perfusion Scan (Blood Flow Test)

   • A small amount of Technetium-99m labeled macroaggregated albumin (MAA) is injected into a vein.
   • A gamma camera captures images of blood flow in the lungs.

3. Comparison of Ventilation & Perfusion Images

   • If there is normal airflow but reduced blood flow, it suggests a pulmonary embolism (PE).
   • If both ventilation and perfusion are abnormal, it may indicate lung disease (e.g., COPD, pneumonia, or fibrosis).

Precautions for a Lung Perfusion/Ventilation Scan

Before the Test

✅ Fasting:

• No fasting is required, but avoid heavy meals before the test.

✅ Hydration:

• Drink plenty of water before the test unless instructed otherwise.

✅ Medication Restrictions:

• Inform your doctor about blood thinners (e.g., warfarin, heparin) or asthma medications.
• If you have COPD or asthma, bring your inhalers in case you need them.

✅ Recent CT or X-ray Studies:

• Inform your doctor if you recently had a chest CT scan with contrast.
• A CT pulmonary angiogram (CTPA) is sometimes preferred over a V/Q scan for detecting PE.

✅ Pregnancy/Breastfeeding:

• Inform your doctor if you are pregnant or breastfeeding, as the radioactive tracers could affect the baby.
• Breastfeeding mothers may need to pump and discard milk for 12–24 hours after the test.

During the Test

• Stay still during imaging to avoid blurry results.
• You may feel mild dizziness after inhaling the radioactive gas.
• Inform the technician if you have trouble breathing, chest pain, or anxiety.

After the Test

✅ Drink plenty of water to flush out the radioactive tracer.
✅ Resume normal activities and diet unless otherwise instructed.
✅ Avoid close contact with infants or pregnant women for a few hours if advised.