What is a VQ scan? Why is this test important to know about your lungs? (VQ Scan)

Have you suddenly had difficulty breathing or chest pain and the doctor told you to do a VQ scan? You may have felt a little scared when he said that. "What is this VQ scan?" "What does it look like?" "Does it hurt?" Many questions may come to mind. Don't worry, we will talk about this very simply today, in a way that you can understand.

Simply put, what is a VQ scan?

The VQ scan is a painless, two-part test that takes pictures of your lung function. It mainly looks at how well your lungs are working and how well your blood is flowing through them .

This is the meaning of the two letters in its name.

• The letter "V" stands for Ventilation . It is the process by which air enters and leaves the lungs when you breathe.
• The letter "Q" stands for Perfusion . It refers to the amount and flow of blood supplied to the tiny blood vessels in the lungs.

Simply put, this is like checking whether the roads in a city (airways) are in good condition and whether there is no traffic congestion on those roads (blood circulation).

Why would a doctor recommend a VQ scan?

The main and most common reason a doctor orders this test is when they suspect a blood clot in the lungs. This condition is medically known as a pulmonary embolism (PE) . This can be a very dangerous condition , so it is important to get a diagnosis and treatment as soon as possible.

In addition, this VQ scan is used in several other situations:

• Recognize the condition ``Chronic Thromboembolic Pulmonary Hypertension (CTEPH),`` which is a disease that increases blood pressure in the lungs.
• Check lung function after a lung transplant.
• Before surgically removing part or all of a lung, check the function of the remaining lung.
• Assess lung function in someone with other lung diseases, such as COPD.

What actually happens in this test?

Okay, now let's see what happens inside this test. This is done in two parts on the same day, one part is done as soon as the other is finished.

1. Part 1 (Ventilation): In this, you wear a special breathing device (like a mask). You are made to breathe through it. A very small, safe radioactive substance ``tracer'' is added to the air you breathe. This is like putting a small 'tag' in the air. Then a special camera takes pictures. Because of that 'tag', the places where air moves in your lungs can be clearly seen in the pictures.

2. Part 2 (Perfusion): In this, a similarly safe radioactive substance (tracer) is injected into a vein in your arm. This 'tag' travels with the blood throughout your body and into your lungs. The same camera used earlier takes pictures again. This shows where the blood is flowing in your lungs.

By comparing these two images, the doctor will determine if there is a problem with your lungs.

How is a VQ scan different from a CT scan?

This is a question that many people have. Although both VQ scans and CT scans take pictures of the lungs, there are some important differences between the two.

Do I need to prepare before the test?

This is the best thing. There is no special preparation required for a VQ scan. You can eat, drink, and take your medications as usual. However, there are a few things you should definitely tell your doctor:

• If you are pregnant or suspect you are: Your doctor may recommend another test, as radiation can affect the fetus.
• If you are a breastfeeding mother: Since radiation can pass to your baby through breast milk, you may be asked to stop breastfeeding for a few hours or a day after the test and express and discard the breast milk. Your doctor will give you instructions on this.
• If you have difficulty staying still for long periods of time: It's best not to move while taking pictures. Doing so will result in blurry images and a poor report.

Usually, a chest X-ray is performed 24 hours before the VQ scan. The information obtained from this will also help in understanding the VQ scan report.

What happens during the test?

The entire test takes between 30 and 60 minutes.

Part One: Ventilation Scan

In this, you will be seated in a chair or lying on a table. You will be given a mask or mouthpiece to breathe through. Then, a camera will take pictures as you breathe through it. You may also be turned in different directions to take pictures.

Part Two: Perfusion Scan

This will begin as soon as the first part is over. This involves putting an IV in a vein in your arm and injecting a radioactive substance through it. Then, as before, pictures are taken with a camera.

What happens after the test? What does the report say?

After the test is over, you can go about your normal activities. The radioactive material that was put into your body will naturally leave your body in your urine and stool within a few hours or days.

The report is usually received within 24 hours. Let's simply see what the contents of the report say.

Is there any risk in this?

The risks of a VQ scan are very minimal . The possible risks are:

• Radiation exposure: This uses a very small, safe amount of radiation. It is completely eliminated from the body within a few days.
• Allergic reaction: The chance of having an allergic reaction to the vaccine is very small, but it is usually mild.
• Minor discomfort: There may be some slight pain during the injection and having to remain still during the test.

At what point do you need to see a doctor urgently?

If you have the following symptoms, it could be a sign of a blood clot in the lungs (Pulmonary Embolism). In such a case , go to the nearest hospital Emergency Department (ETU) immediately.

• Sudden severe shortness of breath
• Sharp pain in the chest, arm, shoulder, neck, or jaw
• Coughing with or without blood
• Pale skin and sweating
• Blue discoloration of the skin, lips, or fingernails (Cyanosis)
• Heart palpitations
• Excessive sweating

VQ scan, ventilation-perfusion scan, pulmonary embolism, lung, blood clot, shortness of breath, chest pain