Renal perfusion scintigraphy is a diagnostic nuclear medicine procedure used to assess renal perfusion and is of particular importance in monitoring the function of transplanted kidneys. To determine renal perfusion, a radiopharmaceutical (radiolabeled substance) is administered intravenously (into the vein) to the patient, allowing precise imaging of renal perfusion.
Indications (areas of application)
- Kidney transplantation – postoperative control of the transplanted kidneys must be performed to verify proper function. Renal perfusion scintigraphy is an important part of the postoperative control examination.
- Acute complications after kidney transplantation – In acute loss of kidney function after transplantation has taken place, renal perfusion scintigraphy is indicated because the procedure is a very sensitive method (probability that a pathological finding found is really present).
- Chronic complications after renal transplantation – perfusion, and therefore renal performance, can deteriorate over a long period postoperatively. Renal perfusion scintigraphy is useful for checking this perfusion.
- Renal perfusion disorders – renal perfusion scintigraphy is indicated in the assessment of perfusion disorders even in nontransplanted kidneys.
- Exclusion of graft rejection – after successful transplantation and reduced or completely absent renal function, renal perfusion scintigraphy can be used to exclude a hemodynamic (affecting blood flow) cause of the dysfunction.
Contraindications
Relative contraindications
- Lactation phase (breastfeeding phase) – breastfeeding must be interrupted for 48 hours to prevent risk to the child.
- Repeat examination – no repeat scintigraphy should be performed within three months due to radiation exposure.
Absolute contraindications
- Gravidity (pregnancy)
Before the examination
- Basic diagnostics – renal perfusion scintigraphy represents a more advanced diagnostic procedure. However, laboratory values (e.g., creatinine clearance) should be determined and diagnostic measures such as renal ultrasonography should be performed first, among others.
- Application of the radiopharmaceutical – various radiopharmaceuticals can be used as radioactive substances in renal perfusion scintigraphy. Among others, scintigraphy is performed with 99mTc-pertechnetate, and the radiopharmaceutical is administered intravenously as a bolus. Furthermore, renal perfusion scintigraphy can be performed with 99mTc-diethylene triamine pentaacetate, which is also applied intravenously. With 99mTc-diethylenetriamine pentaacetate, it should be noted that the substance is filtered exclusively glomerularly (via the renal corpuscles). The amount of radiopharmaceutical used depends on gender and body volume.
The procedure
The basic principle of renal perfusion scintigraphy is based on the imaging of the respective applied radiopharmaceutical in the arterial vascular system of the kidney. For optimal results of the diagnostic procedure, it is important that the patient be placed in the supine position following the injection of the radiopharmaceutical. When performing renal perfusion scintigraphy as a postoperative follow-up examination of a kidney transplant, the patient is asked to place his or her hand on the surgical area. The inserted camera is then adjusted to the patient’s hand. After the patient removes their hand from the surgical area, sequence images can be obtained. First, the physician creates planar sequence images from different positions, which are then used to calculate the perfusion index. The perfusion index calculation is based on plotting the measured radioactivity against time. Combination of renal perfusion scintigraphy with other diagnostic procedures.
Renal perfusion scintigraphy can be enhanced by the administration of a renal (affecting the kidney) drug.Of diagnostic importance is the combination of renal perfusion scintigraphy with the simultaneous administration of captopril (ACE inhibitor – antihypertensive drug). This combination procedure is used in cases of suspected pathological renal artery stenosis, provided that symptoms such as hypertension (high blood pressure) with flank pain or worsening of renal function have occurred under ACE inhibitor therapy. The radiopharmaceutical used in combination diagnosis is 99mTc-MAG3. As a follow-up, renal perfusion scintigraphy with 99mTc-MAG3 should be performed without concomitant captopril use.
After the examination
- No special measures are necessary after scintigraphy. The further procedure after the examination must be discussed with the attending physician.
Possible complications
- Intravenous application of radiopharmaceutical may result in local vascular and nerve lesions (injuries).
- Radiation exposure from the radionuclide used is rather low. Nevertheless, the theoretical risk of radiation-induced late malignancy (leukemia or carcinoma) is increased, so that a risk-benefit assessment should be performed.
- Combining an ACE inhibitor with renal perfusion is associated with higher risks.
