Ventilation/Perfusion Scan

A ventilation/perfusion scan, also known as a V/Q scan, is a medical imaging test used to evaluate lung function and diagnose certain conditions, such as pulmonary embolism.

What is the purpose of a Ventilation/Perfusion Scan?

The primary purpose of a V/Q scan is to assess how well air moves in and out of the lungs (ventilation) and how well blood flows through the lungs (perfusion). This information helps doctors diagnose and manage conditions that affect lung function.

How is a Ventilation/Perfusion Scan performed?

A V/Q scan typically involves two separate scans:

• Ventilation scan: The patient inhales a small amount of radioactive gas, such as xenon-133 or krypton-81m, through a mask. The gas is distributed throughout the lungs, and a special camera (gamma camera) detects the radiation emitted by the gas, creating images of lung ventilation.
• Perfusion scan: The patient is injected with a small amount of radioactive material, such as technetium-99m macroaggregated albumin (MAA), into a vein. The material travels to the lungs and is distributed according to blood flow. The gamma camera detects the radiation emitted by the material, creating images of lung perfusion.

What are the indications for a Ventilation/Perfusion Scan?

V/Q scans are commonly used to:

• Diagnose pulmonary embolism (blood clots in the lungs)
• Evaluate lung function before surgery
• Assess lung damage after injury or infection
• Monitor chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) or pneumonia

What are the benefits and risks of a Ventilation/Perfusion Scan?

Benefits:

• Non-invasive and relatively painless
• Provides valuable information about lung function and blood flow
• Helps diagnose and manage various lung conditions

Risks:

• Exposure to small amounts of radiation
• Allergic reactions to the radioactive materials (rare)
• Claustrophobia or anxiety during the scan (rare)

What are the limitations of a Ventilation/Perfusion Scan?

V/Q scans have some limitations, including:

• May not provide detailed information about lung anatomy
• May not detect small blood clots or other conditions
• May be affected by various factors, such as patient movement or respiratory disease

What are the alternatives to a Ventilation/Perfusion Scan?

Alternative imaging tests that may be used instead of or in addition to a V/Q scan include:

• Chest X-ray
• Computed Tomography (CT) scan
• Magnetic Resonance Imaging (MRI)
• Pulmonary angiography