Renal Scintigraphy

What Is Renal Scintigraphy?

Renal scintigraphy is a nuclear medicine procedure that can be used to assess the shape, location, and size of the kidneys and their function. In addition, the outflow of urine from the kidneys and the blood flow to the organs can also be examined. For this purpose, radioactive drugs (radiopharmaceuticals) are administered, accumulating in the kidney for a short time before being excreted. These radiopharmaceuticals emit radiation that is recorded by a gamma camera. Based on this imaged scintigram, the physician can make statements about the kidneys and possible diseases.

A distinction is made between static renal scintigraphy, in which the radiopharmaceutical accumulates in the functioning kidney tissue, and only this is visible in the scintigram. The physician can estimate the approximate kidney function and make statements about the shape, size, location, and any morphological abnormalities.

Furthermore, there is dynamic renal scintigraphy (renal sequence scintigraphy, functional scintigraphy), by which the blood flow to the kidneys, the renal function (especially the clearance and glomerular filtration rate), and the urine outflow can be assessed.

When Is Renal Scintigraphy Carried Out?

In general, renal scintigraphy is usually carried out when abnormalities have already been found in other examinations, such as ultrasound or blood analysis, or when specific diseases are known in the patient's medical history.

Renal scintigraphy is carried out to show the renal function of the two kidneys in a side-by-side comparison, especially if diseases that potentially affect the function of a single kidney are familiar. These include, for example, kidney stones, tumors, and previous inflammations, but also kidneys that are altered or malformed in their position in the body congenital or as a result of other diseases (e.g., scars, degenerative kidney diseases, horseshoe kidneys, cirrhosis of the kidneys, nephroptosis). It can be determined whether individual areas of a kidney or the entire organ are restricted in their detoxification function. Scintigraphy is also a diagnostic option for urinary outflow disorders or obstructions of the urinary tract. In addition, it can be used before kidney transplantation to assess the organ to be transplanted and before living donation to assess excretory function and, thus, donor suitability.

Renal scintigraphy can also be helpful in emergencies to detect possible injury to the kidneys, sudden vascular occlusion of the renal vessels, acute urinary retention, or leakage of urine into the body.

How Is Renal Scintigraphy Performed?

Before a renal scintigraphy examination, the patient is informed by a knowledgeable physician about the benefits and possible risks of the procedure. Radiation exposure is very low, and the method is even used in children. Preliminary examinations such as an ultrasound, determining important blood values, and interrogating the medications taken are usually necessary. Pregnancy should be excluded, and nuclear medical examinations are also not performed if the patient is breastfeeding or has significantly impaired kidney function.

The patient should consume sufficient liquid (1-1.5 liters) about one hour before the scintigraphy (as a drink or an infusion) and empty the bladder afterward. Then, the radioactive drug is injected into a vein and quickly enters the bloodstream. In static renal scintigraphy, DMSA-99m-Tc is used as the radiopharmaceutical, and after about 2 hours, imaging can be performed with a gamma camera. The radiation emitted by the injected drug, which has accumulated in the kidney, is captured and imaged. For this purpose, the patient is positioned lying in front of the camera, once from the front and once from the back; the procedure is entirely painless. Dynamic renal scintigraphy is most commonly performed with the radioactive drug MAG3-99m-Tc. It is also injected, but in this case, the gamma camera images are taken immediately afterward and then at specific time intervals up to 30 minutes after injection to image the formation, secretion, and excretion of the radiopharmaceutical in the kidney. Blood is also drawn several times to measure the radioactivity of the drug. Under certain conditions, a diuretic, i.e., a drug for dehydration, is administered during or after the examination.

Finally, the physician receives scintigraphy images of the kidneys for evaluation and specific diagrams and values to assess the organs and any diseases.

How Long Does Renal Scintigraphy Take?

The actual scintigraphy in front of the gamma camera typically takes only 20-30 minutes. However, additional preparation time must be calculated. In the case of static renal scintigraphy with DMSA-99m-Tc, the examination can only be carried out after about 2 hours, plus the time required for informing, venous access must be established, possibly an infusion is given, and finally, the radiopharmaceutical is applied. Therefore, about 3-4 hours should be planned.

Dynamic renal scintigraphy takes less time, as the examination begins immediately after administering the radioactive drug and lasts about 30 minutes. Including all preparations, about one hour is needed.

What Can Be Assessed with Renal Scintigraphy?

Using static renal scintigraphy, the physician can subsequently assess the kidney morphology, i.e., make statements about the localization, shape, and size of the kidneys. Malformations such as horseshoe kidneys, double kidneys, or even scars in the organs can be detected. Since only the functioning kidney tissue is visualized, the proportional function of the right and left kidneys can be analyzed separately; usually, both organs work about equally. However, a scarred or malformed kidney, for example, will accumulate much less radiopharmaceutical than a healthy one; the damaged kidney will appear paler in the scintigram, and the physician will recognize that it contributes little or not at all to the detoxification of the body.

With dynamic functional scintigraphy, the clearance can be assessed as a functional value of the kidney. Clearance measures the amount of blood that can be cleansed of a substance in a given time. Another measured value is the glomerular filtration rate, which describes the amount of urine filtered from the blood by the kidney at a particular time. Each kidney can be assessed individually, and side-by-side comparison can be made. It is also possible to plot specific activity curves to represent kidney function over time accurately.

In addition to these values, a scintigram also shows urine outflow. Constrictions or pathological reflux of urine become visible.

In addition, dynamic renal scintigraphy allows conclusions to be drawn about the blood supply to the kidneys, which is important, for example, for diagnosing constrictions of the vessels.

Which Doctors and Clinics are Specialists in the Field of Renal Scintigraphy?

Every patient who needs a doctor wants the best medical care. Therefore, the patient is wondering where to find the best clinic. As this question cannot be answered objectively, and a reliable doctor would never claim to be the best one, we can only rely on a doctor's experience.

We will help you find an expert for your condition. All listed doctors and clinics have been reviewed by us for their outstanding specialization in renal scintigraphy and are awaiting your inquiry or treatment request.

Source:

• Leitlinie Verfahrensanweisung zur Nierenfunktionsszintigraphie

www.nuklearmedizin.de/leistungen/leitlinien/html/nierenfunkt_szin.php

• Amboss Apparative Diagnostik in der Urologie

www.amboss.com/de/wissen/Apparative_Diagnostik_in_der_Urologie/

• Universitätsklinikum Halle Nierenfunktionsszintigraphie

www.medizin.uni-halle.de/einrichtungen/kliniken-und-departments/department-fuer-strahlenmedizin/abteilung-fuer-nuklearmedizin/patientinnen-und-patienten/nierenfunktionsszintigraphie