Pulmonary ventilation/perfusion scan

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Pulmonary ventilation/perfusion scan

Definition:

A pulmonary ventilation/perfusion scan is a pair of nuclear scan tests that use inhaled and injected radioactive material (radioisotopes) to measure breathing (ventilation) and circulation (perfusion) in all areas of the lungs.

Alternative Names:
V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan
How the test is performed:

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A pulmonary ventilation/perfusion scan is actually 2 tests that may be performed separately or together.

The perfusion scan is performed by injecting radioactive albumin into a vein. The patient is immediately placed on a movable table that is positioned under the arm of a scanner. The lungs are scanned to detect the location of the radioactive particles as blood flows through the lungs.

The ventilation scan is performed by scanning the lungs while having the person inhale radioactive gas. A mask is placed over the nose and mouth, and the patient is asked to breathe the gas while sitting or lying on the table beneath the arm of the scanner.

How to prepare for the test:

No special diet, medications, or fasting are necessary before the test.

A chest x-ray is usually performed prior to or following a ventilation and perfusion scan.

You will sign a consent form and wear a hospital gown or comfortable clothing without metal fasteners.

Infants and children:

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

Infant test or procedure preparation (birth to 1 year)
Toddler test or procedure preparation (1 to 3 years)
Preschooler test or procedure preparation (3 to 6 years)
Schoolage test or procedure preparation (6 to 12 years)
Adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

The table may feel hard or cold. You may feel a sharp prick during injection of material into the vein for the perfusion portion of the scan. The mask used during the ventilation scan may give you a claustrophobic feeling. You must lie still during scanning.

The radioisotope injection usually does not cause discomfort.

Why the test is performed:

The ventilation scan is used to evaluate the ability of air to reach all portions of the lungs. The perfusion scan measures the supply of blood through the lungs.

A ventilation and perfusion scan is most often performed to detect a pulmonary embolus. It is also used to evaluate lung function in people with advanced pulmonary disease such as COPD and to detect the presence of shunts (abnormal circulation) in the pulmonary blood vessels.