Magnetic Resonance Urography (MRU)

What is magnetic resonance urography?

Magnetic resonance urography (MRU) is an exam that uses magnetic waves to create detailed pictures of the kidneys, ureters and bladder. It is a radiation-free way to look at the structure and function of the urinary tract, which is the part of the body that produces and transports urine.

The MRU study is done in a magnetic resonance imaging (MRI) machine. A urinary catheter (tube inserted through the urethra and into the bladder) and an intravenous (IV) catheter (tube inserted through the skin into the vein) are required. Together, these catheters help us measure drainage of the urine to assess the function of your child’s kidneys. The MRU study takes about one hour.

What to expect before the MRU

Your child must arrive at least two hours before the test. A registered nurse will insert the IV catheter and administer fluid through this catheter before the test. The urinary catheter will also be inserted prior to the test. This tube will help the bladder drain.

Important information

Some medical devices placed into the body contain metal and cannot be near the strong magnets of an MRI machine. For this reason, we need to know if a child has metal in or on their body to make sure it is safe for them to have this test. Your child should not wear metal, jewelry or glitter makeup/tattoos to the examination. Situations in which this test may not be used include:

  • Metal in any part of the body
  • Pacemaker or cardiac defibrillator
  • Brain aneurysm clip
  • Cardiac stent
  • Stimulators
  • Pregnancy

What to expect during the MRU

The images are obtained while your child is lying face down, very still, inside the MRI machine. Lying in this position helps the kidneys drain the urine. There is a speaker system and video monitor inside the MRI room so your child and our staff can speak to each other.

Medications are administered through the IV catheter, including furosemide and contrast. Furosemide will help the kidneys drain the urine faster, and the contrast will show how the kidneys work. Both medications are necessary to check the function of the kidneys.

What to expect after the MRU

Once the exam is complete, a registered nurse will remove the IV and urinary catheters. Some children report a small amount of burning when they first urinate after the catheter is removed. The radiologist will review your child’s pictures and send a written report to the provider who requested the study.

If sedation is required

If your child requires sedation in order to successfully complete the MRU, you will need to speak with a sedation/radiology nurse before scheduling the procedure. Your child will not be able to eat or drink before the study. Specific instructions will be discussed the day before the test. For children being sedated, the urinary catheter is placed after the child is asleep.