Norm of Renocystogram (Renogram Scan, Renal Scan)
Radionuclide contrast material should circulate bilaterally, symmetrically, and without interruption through the renal parenchyma, ureters, and urinary bladder; 50% of radionuclide should be excreted within the first 10 minutes. The initial uptake or vascular phase occurs within 30–45 seconds after administration of the radionuclide. The transit or tubular phase follows over the next 2–5 minutes, and drainage of the radionuclide from the kidneys occurs during the excretory phase.
Captopril Radiography Method
Renovascular hypertension: GFR decreases more than 20%, with a 10% difference between the left and right kidneys.
Renal Artery Stenosis
The kidney shows a disproportionate reduction in perfusion after administration of captopril.
Usage of Renocystogram (Renogram Scan, Renal Scan)
Azotemia, excretory defects, nephroureteral dilation, renal ischemia (acute tubular necrosis), renal obstruction or mass, renal parenchymal disease, renovascular hypertension, unilateral kidney disease, and upper urinary tract obstruction; assessment of renal perfusion and status before transplantation and after transplantation (to differentiate between acute tubular necrosis and transplant rejection); evaluation of hydroureteronephrosis and urinary tract patency; also used for clients hypersensitive to iodine-based contrast material used with intravenous pyelography or those in whom urethral catheterization is contraindicated. This study records the activity of the entire kidney but does not distinguish between specific areas of disease within the kidneys.
Description of Renocystogram (Renogram Scan, Renal Scan)
The renocystogram is a dynamic nuclear medicine study of the kidneys and ureters in which the dispersion, clearance, and excretion of a radionuclide are recorded by means of a gamma radiographic scan. Radionuclide uptake, transit, and excretion times are computed, and renogram curves are plotted on a graph for each kidney and ureter. Quantitative evaluation of renal function occurs as the external radiation detectors record vascular supply, perfusion, tubular filtration, and excretory phases. A renogram curve is produced as the radionuclide dispersion is plotted on a graph or computed. Comparisons of the right and left kidneys, curve shapes, and relative functions are calculated. Curve shapes are characteristic of certain disorders. This scan uses less radiation than an IVP or CT scan. However, IVP is better for anatomic definition, and arteriography is better for assessment of renal arterial anatomy. Renocystogram is superior to magnetic resonance imaging for medullary renogram evaluation (which must derive medullary information from a mixed study renogram), but equivalent in use for cortical renograms. When the evaluation is being done to identify the presence of renal vascularization abnormalities in hypertension and suspected renal artery stenosis, captopril radiography may be used. For suspected renal artery stenosis only, duplex ultrasound is less costly and invasive and provides similar diagnostic accuracy to captopril radiography.
Professional Considerations of Renocystogram (Renogram Scan, Renal Scan)
Consent form IS required.
Allergic reaction, bleeding, infection, urinary tract obstruction.
During pregnancy, this test is performed only when imperative. It is contraindicated during breast-feeding, with congenital renal abnormality, clients with open flank wounds present, or with previous allergic reaction to the same radionuclide.
During pregnancy, risks of cumulative radiation exposure to the fetus from this and other previous or future imaging studies must be weighed against the benefits of the procedure. Although formal limits for client exposure are relative to this risk:benefit comparison, the United States Nuclear Regulatory Commission requires that the cumulative dose equivalent to an embryo/ fetus from occupational exposure not exceed 0.5 rem (5 mSv). Radiation dosage to the fetus is proportional to the distance of the anatomy studied from the abdomen and decreases as pregnancy progresses. For pregnant clients, consult the radiologist/ radiology department to obtain estimated fetal radiation exposure from this procedure. In women who are breast-feeding, formula should be substituted for breast milk for 1 or more days after the procedure.
- Obtain the client's current weight.
- The client should empty the bladder. Insert an indwelling urinary catheter for pediatric clients.
- Establish intravenous access and infuse 500 mL of IV fluids (unless contraindicated). Unless contraindicated, the client should be well hydrated with 10 mL of water per kilogram of body weight.
- Have emergency equipment readily available.
- Just before beginning the procedure, take a “time out” to verify the correct client, procedure, and site.
- The client is positioned upright.
- After placement of external posterior radiation detectors over both kidneys, an intravenous injection of radionuclide 99mTc-DTPA (technetium with the chelating agent diethylenetriaminepentaacetic acid) or 131I-ortho-iodohippurate (radioiodine hippuran) is administered. Detectors record the uptake and excretion radiation counts when gamma scanning of both kidneys is completed.
- The scan takes about 45 minutes.
- If captopril renography will be done, captopril is administered and the scan is repeated 1 hour later. Monitor blood pressure every 15 minutes throughout the procedure.
- Urine or serum blood samples may be obtained.
- Assess the injection site for infiltration of radionuclide analog.
- Observe the client carefully for up to 60 minutes after the study for a possible (anaphylactic) reaction to the radionuclide.
- When urine is being discarded, rubber gloves should be worn for 24 hours after the procedure. Wash the gloved hands with soap and water before removing the gloves. Wash the ungloved hands after gloves are removed.
- If captopril was administered, continue blood pressure measurements every 30 minutes until the client meets discharge criteria. Assess for orthostatic hypotension.
Client and Family Teaching
- This is a screening test used when it is suspected that renal blood flow is reduced.
- This examination takes approximately 45 minutes and involves receiving an IV line to administer the test material and some fluids.
- Immediately flush the toilet after each voiding after the procedure, and meticulously wash your hands with soap and water after each void for 24 hours after the procedure.
- There will be a small amount of radiation exposure during testing.
- For captopril renography, eat and drink only liquids beginning midnight before the test. Do not ingest any milk products.
- For captopril renography, you will be given a glass of water to drink.
- For captopril renography, you will need to slowly change from a lying or sitting position to a standing position, in case you experience dizziness.
- If you are breast-feeding, substitute formula for breast milk for 1 or more days after the procedure.
Factors That Affect Results
- The presence of contrast material from prior diagnostic testing within 7 days interferes with accuracy.
- Abnormalities may be accentuated in the presence of dehydration or masked in the presence of overhydration.
- Injection of radiographic contrast material within 24 hours before the test invalidates the results.
- Health care professionals working in a nuclear medicine area must follow the federal standards set by the Nuclear Regulatory Commission. These standards include precautions for handling the radioactive material and monitoring of potential radiation exposure.
- Technetium half-life is 6 hours.