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Right-to Left Shunt Study

WB MAA Study


  • You have been referred for a Right-to Left Shunt Study (WB MAA Study) in which imaging of your whole body (WB) is done.

  • A WB MAA Study is very sensitive in looking at the systemic/pulmonary ratio (SPR) in individuals suffering from Hepatopulmonary Syndrome (HPS).

  • Hepatopulmonary syndrome is defined by hypoxemia, an increase of alveolo-arterial gradient during inhalation of room air and intrapulmonary vascular dilatation in the presence of hepatocellular insufficiency.

  • In R-L shunts, deoxygenated blood crosses into the left system, diluting the oxygenation being delivered to the systemic tissues and resulting in hypoxia.

  • The test involves a small injection of  “tracer” (like having a blood test).

  • The tracer we use is called 99mTc-MAA (99m-Technetium Micro Aggregated Albumin).

  • There are rarely any side effects with this injection.

  • Images are done immediately following the injection of your WB using a Gamma Camera (1). This takes 10 minutes.

  • You receive a slight radiation dose by having a WB MAA Study  ~ up to 0.7 times your yearly background radiation (2).


Patient Preparation:

  • If you are pregnant, trying to fall pregnant or breast feeding, you must inform our staff.

  • If you have had prior imaging e.g. PET, Nuclear Scan, CT, MRI, X-Ray, Ultrasound, etc... please bring these with you.

  • Please also bring your referral and any blood results that you may have had done.

  • There is no preparation for a WB MAA Study i.e. eat and drink as normal.

  • If you are on any medications, please take these as normal.

  • Wear comfortable clothing and minimise the amount of metal jewellery you have on (all metal objects will need to be removed prior to imaging).

  • Important Note: You cannot have this test if you have had a PET or Nuclear Scan within 24 hours prior to this test. If you have had Iodine-131 therapy, allow 4-weeks before having this test. Please ring to discuss booking options.​


Breast-Feeding Mothers: Once you have been given the tracer, you need to stop breast-feeding for 13-hours. During this time, you need to express and discard your breast milk as often as required. You will need to bottle-feed your child during this period.



(1) A Gamma Camera is a device that detects gamma-rays (gamma-rays are very similar to x-rays) and does not emit any radiation.

(2) We all receive a yearly background radiation dose ~ 2.4mSv. WB MAA Study ~ 1.7mSv = 0.7 times yearly background dose.

value. quality care. convenience.

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