How It Is Done
A kidney scan is usually done by a nuclear medicine technologist.
The scan pictures are usually interpreted by a
radiologist or
nuclear medicine specialist.
You will need to remove any jewellery that might interfere with the
scan. You may need to take off all or most of your clothes, depending on which
area is being examined (you may be allowed to keep on your underwear if it does
not interfere with the test). You will be given a cloth or paper covering to
use during the test.
The technologist cleans the site on your arm where the radioactive
tracer will be injected. A small amount of the radioactive tracer is then
injected. Medication to increase your urine output (a diuretic) may also be
injected. You may lie on your back on a table, stand, or sit upright. A large
scanning camera will be positioned closely above your abdomen. After the
radioactive tracer is injected, the camera will scan for radiation released by
the tracer and produce pictures as the tracer moves through your
kidneys.
You need to lie very still during each scan to avoid blurring the
pictures. The camera does not produce any radiation, so you are not exposed to
any additional radiation while the scan is being done.
For the kidney function study, a different tracer may be injected
and a series of pictures will be taken every few minutes for 30 minutes. These
images monitor flow of the tracer through the kidneys, into the ureters and,
finally, into the bladder. As each picture is being taken, you must lie
completely still. Occasionally, scans may be done while you are sitting upright
or standing. In some studies, other medications such as captopril or a
diuretic, may be given to help assess specific functions of the kidneys.
A chart called a renogram may be made using the information from
the perfusion study scans by plotting the movement of the tracer through the
kidneys and recording it on a graph. A series of chart recordings is then made
based on the amount of tracer uptake in the kidneys over a period of time.
These recordings provide information about different phases of blood flow and
kidney function. Another type of scan, called a static scan, also may be done
several hours after a tracer is injected.
The kidney scan usually takes about 1 to 2 hours but can last up to
4 to 5 hours depending on what functions are being studied.