Before the scan you will be asked to drink plenty of water, as it is important to be well hydrated. Shortly before the test, you will be given a medication called an ACE-inhibitor, either orally or intravenously (through a vein). This is a drug used to treat high blood pressure. It is used in the renal scan to increase the likelihood of identifying a clinically significant renal artery stenosis.

Soon after the ACE-inhibitor is given, you are asked to lie on the scanner table and a small amount of radioisotope is injected into a vein. The kidneys are then scanned for approximately 30 minutes. The images are taken as the radioactive material flows through the renal arteries and into the kidneys. It is very important to remain still throughout the examination. Approximately 10 minutes after the radioisotope is injected, a medication called furosemide is given intravenously. This is a diuretic (commonly known as a water pill), which, like the ACE-inhibitor, increases the accuracy of the test.

After the scan, no recovery time is required. You will be asked to drink plenty of fluids to help excrete the radioactive material from the body.

There is no need for fasting or special diet. You will be asked to drink plenty of water before the scan. If you are currently taking an ACE-inhibitor for high blood pressure, you may be asked to discontinue this prior to the examination. You should always consult with your health care provider before discontinuing any medication.

You may be asked to wear a hospital gown. Remove all jewelry and metallic objects before the scan.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• 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)
• School age test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

There is a small amount of pain when the needle is inserted. You must remain still during the scan, and you will be instructed when to change positions by the technologist. There may be some discomfort as your bladder fills with urine during the examination. Inform the technologist if you must urinate before the completion of the scan.

The test evaluates blood flow to the kidneys, in the setting of suspected renal artery stenosis. Clinically significant renal artery stenosis may be a cause of high blood pressure (hypertension) and kidney problems.

Imaging reveals findings compatible with normal blood flow to the kidneys.

Abnormal findings on the scan using the ACE-inhibitor challenge may indicate renal artery stenosis. This is usually confirmed by comparison with a similar study in the absence of the ACE-inhibitor.

If you are pregnant or nursing, the test may be postponed to prevent exposure to the baby. The amount of radioactivity in the injection is very small, and virtually all activity is gone from the body within 24 hours. Although it is extremely rare with renal perfusion scanning agents, a person may develop rash, swelling, or anaphylaxis.

Any time the body is penetrated (such as by a needle prick) there is a risk for infection. Injection into a vein also carries a slight risk for bleeding. The risk is no greater for renal perfusion scan than for intravenous injection of any sort.

There are certain risks involved with the administration of ACE-inhibitors. You should consult your health care provider to determine if this test is appropriate for you.

The accuracy of this test may be diminished in individuals with pre-existing kidney disease. You should consult your health care provider to determine if this test is appropriate for you.