Introduction
The renal scan provides information concerning renal perfusion, function, morphology and drainage with a single intravenous injection of a radiopharmaceutical. Computer quantification of differential renal function is useful in the evaluation of hypertension or other renal parenchymal or obstructive problems. The use of Captopril in conjunction with a renal scan improves detection of hypertension that is caused by renovascular disease.
The renal scan with the administration of Lasix, is used in differentiating non-obstructive dilation of the urinary tract from ongoing obstruction.
Allergic reactions to nuclear medicine radiopharmaceuticals are rare, and this test may be used safely in patients with sensitivity to x-ray contrast agents.
Radioactive tracers are excreted by filtration by the glomeruli or secretion by the tubules and follow pathways of urinary drainage. Quantification of differential function is possible by this technique, unlike a radiographic or ultrasound examination. Poorly functioning kidneys are better visualized than with an IVP.
Main Indications
- Hypertension (to exclude renovascular hypertension).
- Renal failure.
- Obstructed kidneys, level of obstruction and residual function.
- Trauma: renal function, urine leaks.
- Flank pain, query infarct.
- Renal assessment when iodine sensitivity is present and IVP is contraindicated.
- Vascularity of renal mass lesions (in conjunction with ultrasound).
- Renal excretory pathways, postoperative.
- Lasix stimulation in hydronephrosis, to differentiate obstructed from non-obstructed dilation.
Patient Information
- Please ask the patient to be well hydrated before arriving for the study. Patients undergoing a renal scan with Lasix injection or Captopril administration will be asked to drink additional water on arrival.
- Sulphonamide sensitivity contraindicates Lasix administration.
- Allergic reactions to the radiopharmaceuticals are rare.
- For the renal scan with Captopril, the patient is to be NPO 3 hours prior to the test.
Procedure for Renal Scan ( without Lasix or Captopril administration)
Part I
The patient is given an intravenous injection of the radiopharmaceutical followed by sequential imaging for about 30 minutes.
Total Part I study time 30-45 minutes.
Procedure for Renal Scan with Lasix Administration
- The patient is given an intravenous injection of the radiopharmaceutical followed by sequential imaging for about 15 minutes.
- The patient is asked to void and then a physician administers the Lasix intravenously.
- Sequential imaging continues for another 30 minutes.
Total study time is 1.5 hours.
Renal Scan with Captopril Administration
- Patient must discontinue ACE inhibitors and angiotensin receptor block for 72 hours before the test. Patient should also discontinue diuretics and other anti-hypertensive medications the morning of the test.
- Patient is given 25 mg of captopril orally. Blood pressure is monitored for 60 minutes.
- Sequential imaging is performed for about 30 minutes.
- Depending on the result of the post-captopril scan, the patient may be asked to return for a baseline study.
Total study time is 2 hours.