A MAG3 scan is a nuclear medicine scan that allows your doctor to examine the function and drainage of your kidneys. MAG3 (which stands for Mercaptoacetyltriglycine) is a radiopharmaceutical that is injected into the bloodstream. MAG3 is linked to a radioisotope which emits (gives out) gamma rays which can be detected by a gamma camera.
MAG3 is taken up in the kidneys and passed out into the urine. The camera detects gamma rays emitted from the MAG3 as it is taken up in the kidneys and flows out of the kidneys in the urine to the bladder.
Indirect MicturatingCystogram (Reflux Study)
The MAG3 renogram can be combined with a micturating study to identify reflux of tracer from the bladder into the ureters and kidneys. This can be useful as a non-invasive method of investigating patients with recurrent urinary infections.
MAG3 scan preparation
What is a MAG3 renogram?
A MAG3 renogram involves an injection into a vein in the arm of a small quantity of radiopharmaceutical. This goes around in the bloodstream and is carried to the kidneys. It then gets extracted by the kidneys, so that it accumulates in the bladder. The gamma camera detects the radiation coming from the tracer in the kidneys, the tubes leading from the kidneys to the bladder (the ureters) and the bladder itself. A picture is produced of the kidneys showing what they look like while they are working and also a graph showing how well each kidney is working. This is what is called the renogram.
Are there are any risks?
As the gamma rays are similar to X-rays, there are small risks associated with being exposed to radiation. However, the radiation decays away over a few hours and the amount of radiation used in medical imaging is very low. This is comparable to the natural radiation we all receive from the environment over about two years. In fact, the risks from missing a disorder by not having a bone scan may be considerably greater than the risks of the radiation. If you are concerned about the risks of the radiation, please speak to a member of our team.
Is there any special preparation for the scan?
Yes. In order to get the best pictures of your kidneys you need to drink at least 2 pints (1 litre) of liquid in the two hours before your appointment. Water and refreshments are available in the waiting room at Trinity Medical Imaging, but it is worth making sure you have plenty to drink before you arrive.
You should take any medicines you need as usual. If you leave the department, you do not need to take any special precautions, but if you stay then you should use the special toilet for nuclear medicine patients.Your technologist will show you where the toilet in the department is.
If you are pregnant or breastfeeding
If you are pregnant, or think you may be pregnant, you mustinform the department before attending, and certainly before the radiopharmaceutical is administered.
If you are breastfeeding, please inform the department before attending and you will be advised as to whether you will need to take any precautions. You may be advised to avoid breastfeeding for a few hours afterwards and you may need to express milk before your scan.
Can you bring a relative/friend?
Yes you can, but for reasons of safety, they may not be able to accompany you into the examination room, except in very special circumstances. Please do not bring children with you as they will potentially be exposed to radiation from other patients.
Arriving for your appointment
When you arrive for your appointment, please go to the reception desk, after which you will be shown where to wait until collected by a technologist.
The technologist will explain the procedure, and you have the opportunity to ask any questions. You may be asked some questions about your health, or whether you have had this examination before. You do not need to undress but you should remove any jewellery and metallic objects such as keys, coins or buckles.
What happens during the scan?
You will be taken to the examination room and made comfortable either sitting or lying down. The technologist will position the gamma camera behind your back and pelvis and ask you to keep as still as possible. The technologist will then give you an injection of a drug called furosemide into a vein, generally the one near your elbow. This drug helps the kidneys drain and you may feel that you want to pass water. The needle, attached to a small plastic tube, will generally be left in the vein. After fifteen minutes, the technologist will give you an injection of the radiopharmaceutical through the plastic tube in your arm. The technologist will remain in the control room and watch you through the glass screen in the examination room. It will be necessary to scan you continuously for 20 or 30 minutes. At the end of the scan, you may be asked to empty your bladder and further images may be taken.
Will it be uncomfortable?
No. Apart from the injection, you will not feel anything.
How long will it take?
The scanning process usually takes about 40 minutes, and your total time in the department should be about one hour.
Can I listen to music while I have my scan?
Your technologist will ask you whether you would like to listen to music during your scan. You may bring in a CD or select music from our selection.
Are there any after-effects?
No, not unless you have had the furosemide injection to make you pass more urine. The radiopharmaceutical injection causes no side-effects, nor will you feel drowsy. You can drive home afterwards and go about your normal activities.
In addition to mothers who are breastfeeding, mothers with young children should notify the radiographer, who will explain that it is advisable not to have prolonged close contact with them for the rest of the day. This is to avoid their being exposed to unnecessary radiation.
When will you get the results?
The scan will be examined after your visit and a written report on the findings will be sent to your referring doctor within 7 days.
The radiopharmaceutical required for this examination is ordered especially for you. If you cannot attend your appointment, please let the department know as soon as possible, so that we can use it for someone else.
We hope that this leaflet has answered your questions, but remember that this is only a starting point for discussion about your treatment with the doctors looking after you. Make sure you are satisfied that you have received enough information about the procedure.