Dynamic Renogram What is a dynamic renogram scan? measure the number of gamma ray counts over time and plot the uptake, excretion and clearance Water soluble substances are predominantly data on a graph to form an objective analysis. cleared from the body via the kidneys. The rate at which waste products are cleared is a reflection of But injecting different chemical tracers that are the efficiency of the kidney and referred to as excreted in different ways by the kidney, we can kidney function. infer information about different aspects of kidney function i.e. DTPA is filtered and used to assess Many conditions can affect this function. Without filtration function; MAG3 is secreted by the kidney being able to clear waste products the body would tubular cells and used to assess tubular function eventually deteriorate and eventually one organ (and indirectly assess filtration function) and OIH system after another with begin to fail. It is combines both of these and allows us the assess a imperative that we are able to assess renal parameter called the effective renal plasma flow. clearance or function so that we can intervene and These parameters are all very important for your act in a timeous fashion. doctor. In patients with renal failure it also allows us to see What can I expect to happen? when dialysis will become necessary. In patients with kidney transplants it allows us to see when the Many things can affect kidney function that can transplant starts to deteriorate and oftentimes tell give spurious results. These include: us what is causing the deterioration. • A dehydrated state • A full bladder The throughput of any tracer through the kidney • Immature kidneys e.g. in new-borns also effectively excludes any obstruction that can • Poor injection of the tracer be severely painful and cause rapid renal • Loss of tracer into other body spaces deterioration if not corrected e.g. by kidney stone. • Not following the same protocol between patients In nuclear medicine, we have utilized knowledge of • Not following the same protocol between chemicals that are almost exclusively cleared by successive studies in the same patient the kidneys and attached a radioactive isotope that emits gamma rays that allows us to image the As such the dynamic renogram protocol in our unit clearance process using the detectors of a special has been standardized. The results of our study machine called a gamma camera. Not only can we cannot be compared to that of another unit unless visualize the process, thus allowing us to create an they perform their studies in exactly the same way impression of the overall function, but we can 1 and often required them to use the same type of of the blood vessels that causes this high blood camera and processing software. pressure. Ultimately this vascular response is required to maintain blood flow to the kidneys. This Before the study we will require you to drink condition is called renovascular hypertension. plenty of water – at least 2-3 glasses. Will I feel claustrophobic? An IV line may be place before the study. While not as constricting as MRI scan, the gamma You will be asked to empty your bladder prior camera detectors can come very close to you. to imaging. There are, however, sensors built into the detectors preventing them from touching you. If A bolus injection of the tracer will be given with needs be and/or on request, we may administer a you already lying on the imaging bed. Immediately light sedative to assist us in acquiring the images we start acquiring a series of quick images to without much movement. assess the blood flow to the kidney and then to assess the tracer progression through the kidney. What are the radiation risks involved? After 20 minutes, if excretion and clearance isn’t Nuclear medicine procedures are very safe. Your visually demonstrated from the kidney reservoirs, doctor should have discussed the test you are having with you and will have considered the then a diuretic will be injected causing these benefits of having or not having the investigation, reservoirs to contract and empty. This allows us to before sending us your referral form. However, if assess for obstruction – obstruction prevents the you have any questions at all, please do not reservoirs from emptying. Another run of images hesitate to ask us. is acquired to image this process. Every day we live with all types of risk; this could be from travelling by road, rail or air, smoking a During this time the bladder may fill again. cigarette or using an electrical appliance. There is Oftentimes this may prevent the reservoirs from even a risk from background radiation depending emptying thus simulating obstruction. You will thus on where we live. be asked to empty the bladder and before and after images will be taken. If we are assessing to see if Risks from radiation there is reflux of urine back into the kidneys, a set There is a 1 in 10,000 chance of dying from a road of images will be taken so that we can visualize traffic accident and this is considered very rare. what the effect of pushing the urine out has on Exposure to any type of radiation increases the risk bladder pressure and whether that increased of getting cancer. This includes naturally occurring pressure causes reflux. This is particularly done in radiation. Radiation dose (an amount of radiation) children. is measured in ‘millisieverts’ (usually abbreviated to ‘mSv’) and we naturally receive between 1.5mSv A specialized test requires two separate and 7.5mSv from the sun and our surroundings, renograms where the kidney blood vessels are depending on where we live. This is known as the suspected of being the cause for a patient’s high average level of annual background radiation. The blood pressure. One scan acts as a baseline. The amount of radiation we can give in hospital tests is second requires us to see if there is a change in the regulated by radiation protection authorities. We renal function and curves if we inject or administer a blood pressure agent that “knocks-out” the effect evaluate and test each radiation exposure and give 2 the minimum amount to produce an effective test unchallenged. This is how cancer develops. The result. We give substantially less than our risk again is minimal with scans and only becomes colleagues in the USA. a problem at increased activity associated with radiation treatment. Your test For this reason, and for safety purposes, all female Nuclear medicine uses radioactivity to help patient suspected of being pregnant or uncertain diagnose and treat medical conditions. Risk from will be tested. For therapy patients, the benefit will diagnostic doses is usually very low, for example a be weighed against the risk and discussed with the thyroid scan has an ‘effective dose’ of 1mSv which patient. gives a predicted lifetime risk of developing a cancer by 1 in 20,000. Now compare this to the Will I be a danger to my family? lifetime risk for developing cancer on its own – 1 in 2.32. This would mean you have to do 8600 odd The activity involved in diagnostic studies is thyroid scans before you have the same random extremely low and simply by maintaining a distance lifetime risk for developing a malignancy. This is of approximately one meter from your relative significantly less than conventional x-rays and far protects them. There is no need for specialized less than with CT scans and fluoroscopy. If you are shielding. In fact, since nuclear medicine studies concerned and/or your test is not identified, we use high energy radiation, normally the radiation will be happy to discuss this with you when you would simply pass straight through the other attend your test and provide an exact value. person without interacting with tissue. By Alternatively, see contact details and give us a call. wearing lead shields etc., you slow the beams down thus allowing it to deposit its energy into the What damage can be expected if any? body tissues which is not a desired effect. Finally, by limiting the time of exposure, your family As with all radiation, there is a theoretical risk of members limit the likelihood that they will absorb causing tissue damage when undergoing a nuclear any radiation. We recommend limiting time in medicine scan. When this damage occurs in the close proximity to less than 20 minutes. DNA or chromosomes, the risk of a mutation in But remember the amount of radiation involved in these regions is increased. Such mutations in a Nuclear Medicine is far less than that of developing foetus can cause organ abnormalities conventional x-rays. The risks are minimal. Any or irreparable damage and if early enough with significant risks only really become a problem when high enough radiation dose can even cause foetal therapeutic activity levels are used which are 100- death. Fortunately, the activity used in Nuclear 500 times the activity used for scans. Even where a Medicine scans is incredibly low – much lower pregnant woman is exposed to gamma radiation, than conventional radiology. This decreases this we have yet to see any effect to the foetus or the risk from radiation to the point where the benefit breast tissue. Theoretically it is possible. In practice far outweighs the risk. The risk only becomes it remains to be shown. greater when activity is very high e.g. as with radiation treatments. In fact, this is exactly the How long will the whole scan take? desired effect when treating with radiation. Usually about 1-3 hours (including reporting time).