Ventilation Perfusion Scan Procedure

Ventilation Perfusion Scan Procedure

Ventilation Perfusion Scan Procedure

A set of two lung scans is called a pulmonary ventilation/perfusion (or VQ) scan. Although they are frequently referred to as one operation, the scans can be carried out simultaneously or one after the other. One of the scans evaluates how well your lungs can move air. The other scan reveals the areas of your lungs where blood flows

Both scans use low-risk radioactive material that can be detected by a certain kind of scanner. The substance will be visible in the scanned image and can provide information to your doctor about the health of your lungs. The substance will collect where there is aberrant blood or airflow, which could be an indication of a lung blockage.

Why is Ventilation Perfusion Scan done?

A blood clot on the lung known as a pulmonary embolism can be found with a VQ scan test. A patient may be booked for the operation if they exhibit any of the following signs:

  • chest pain
  • Having trouble breathing
  • quick heartbeat
  • decreased blood oxygen levels

Before requesting a VQ Lung Scan for pulmonary embolism, your doctor will search for risk factors. Lifestyle choices like smoking, eating habits, and physical activity are risk factors. People who spend a lot of time sitting are particularly at risk. Travel, recuperation from surgery, or a sedentary lifestyle could all contribute to immobility. A VQ blood clot test may be performed as a result of certain risk factors.


  • You will receive an explanation from your doctor regarding the VQ scan's process and potential hazards. After the potential hazards have been discussed and you have had an opportunity to ask any questions, you will be required to sign a permission form.
  • You should let your doctor know if you have any known allergies before the test, especially to latex or contrast dyes. By doing this, you may be sure that your doctor and the rest of the medical team are ready in case an allergic reaction occurs during the test.
  • Additionally, you must let your doctor know if you're expecting or nursing a baby. The contrast dye used might get into the breast milk or the fetus.
  • If you've recently undergone a test called a nuclear test, which involved the use of radioactive materials, you should let your doctor know. If so, there might still be radioactive dye in your bloodstream, which could skew the test's outcomes.
  • To avoid having to change into a patient gown, try to wear comfortable clothing without any metal fasteners to the exam. You might want to refrain from wearing jewellery to the exam since you'll need to take off any metal jewellery, including piercings. In most cases, there is no need to fast before the scan or follow any other particular dietary instructions.
  • Additionally, you might be required to get a chest X-ray 24–48 hours before your


  • It takes about 45 minutes to complete the ventilation-perfusion test. While the medical assistant sets up the intravenous line, you will be lying on an examination table (IV). You will have the line placed into a vein on your arm or hand. The IV line could cause you a little discomfort.
  • The technician will administer radioactive dye through the IV line to your bloodstream. This color may contain trace amounts of radioactive technetium. The technician will cut off your IV line once the dye has entered your bloodstream and will then take you to a special scanner.
  • The dye's passage through your bloodstream and into your lungs is tracked by the scanner. Your technician can instruct you to hold still or to move while the scanner takes numerous pictures. The mouthpiece for the next phase of the VQ Scan Test will be given to you by the technician
  • The mouthpiece contains a specific gas that you must breathe through while the scanner takes pictures of your lungs. Avoid breathing in the gas if you can because it could distort your perception of your lungs. For some of the photographs, the technician might urge you to hold your breath.
  • The VQ Scan's imaging phase is finished, and then your technician will take the mouthpiece out. The scanner can then be closed. As you typically breathe, the gas will be naturally expelled from your lungs.

After Care

  • Following the test, you can be watched for a brief period to look for any allergic reactions. Additionally, someone will look for redness and swelling at the IV site. Due to lying down during the exam, you can feel a little lightheaded.
  • After the test, you should consume a lot of water to help your body flush out the radioactive materials. Once you go back home, if you experience any redness, swelling, or pain at the IV site, call your doctor right away as this could be an infection.
  • Unless your doctor advises otherwise, you can continue to eat and drink as usual. Additionally, refrain from any additional nuclear operations over the ensuing 24 to 48 hours.

-         Written By

Simran Kaushal

Nuclear Medicine Technologist



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