: Technetium-99m Mercaptoacetyltriglycine (MAG3) Renal Scan (Kidney Function and Perfusion Imaging Study)

: What the Test Measures

: The scan looks at three main things: blood flow to each kidney (perfusion), how well kidney tissue takes up and clears the tracer (function), and how the tracer moves from the kidneys through the urinary tract (drainage). By comparing the two kidneys over time, your care team can see whether one kidney is working or draining differently from the other.

: How the Procedure Is Done

: You will receive the tracer as an injection into a vein. A special camera placed near your back detects the tracer as it passes through the kidneys and is cleared into the bladder. Images are recorded over a period of time, and you may be asked to lie still, drink fluids, or empty your bladder at certain points. Sometimes a medicine is given to help assess drainage. The test is generally painless apart from the injection.

: How to Prepare

: Your care team will give you specific instructions. You may be asked to stay well hydrated before the test and to empty your bladder right before imaging. Tell the staff about all medicines you take, any allergies, whether you are pregnant or breastfeeding, and any recent imaging studies, because these can affect scheduling and preparation.

: What the Results Mean

: A specialist reviews the images and the time-based measurements to judge each kidney's blood flow, function, and drainage. Results are usually described as normal, or as showing reduced function or delayed drainage on one or both sides, and are interpreted together with your symptoms, other imaging, and lab tests. Ask your provider to explain what your specific results mean for your care, since findings alone do not diagnose a condition.