Renal Function Scintigraphy

Renal function scintigraphy (synonym: renal sequence (function) scintigraphy) is a diagnostic procedure in nuclear medicine. Renal function scintigraphy is of high value for nuclear medicine diagnostics of the kidney, as the function of both kidneys can be evaluated (examined) individually or in combination with the help of this procedure. In this regard, renal sequence (functional) scintigraphy allows estimation of renal blood flow (vascular phase), visualization of functional renal parenchyma (parenchymal phase/renal tissue phase), depicts the excretory phase (excretion of radiopharmaceutical from renal parenchyma via renal pelvis and ureters/ureters into the bladder), and also allows determination of whether radioactive urine flows back from the bladder into the kidney (vesicorenal reflux).

Indications (areas of application)

  • Side-by-side functional assessment of the kidneys – renal function scintigraphy is performed for: Outflow obstruction, postoperative follow-up, and suspected vesicorenal reflux (determination of whether radioactive urine is refluxing from the bladder into the kidney.
  • Nephrolithiasis (kidney stone disease) – in this often unilaterally emphasized pathological (pathological) findings, renal function scintigraphy is an important diagnostic procedure, because using this method, an optimal side-separated renal function determination can be made.
  • Renal tumors – analogous to nephrolithiasis, a side-separated clarification of function is also necessary and possible in the case of a renal tumor, regardless of its origin.
  • Double kidney – in the presence of a double kidney, the functional assessment of the present partial function is of great diagnostic importance.
  • Hypertension – in the case of suspected renal hypertension (renal hypertension), renal function scintigraphy is essential in the diagnosis.
  • Kidney transplant – the assessment of the function of a transplant kidney is possible by renal function scintigraphy. Furthermore, the procedure is also used in progress controls after successful transplantation.
  • Renal embolism – if renal embolism is suspected, the procedure should be used as part of emergency diagnostics.
  • Traumatic loss of kidney function – to rule out possible kidney trauma, the procedure should be used as part of the emergency diagnostic workup.

Contraindications

Relative contraindications

  • Lactation phase (breastfeeding phase) – mothers should discontinue breastfeeding for 48 hours to avoid 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

  • Drug history – due to interference with renal function measurement, it must be known if ACE inhibitors are taken by the patient. Renal function scintigraphy is performed with an ACE inhibitor in addition to the native form, so if the medication is unknown, the measurement would not be meaningful.
  • Basic diagnostics – renal function scintigraphy represents an important diagnostic procedure, which is usually combined with additional procedures. Previously, as a rule, among other things, laboratory values (creatinine clearance) are determined and diagnostic measures such as renal sonography are performed.
  • Hydration – before the examination, ensuring adequate hydration (drinking enough water) is crucial for the procedure to be performed.
  • Application of the radiopharmaceutical – via a previously placed venous access, 99mTc-mercapto-acetyltriglycine is usually administered as a radioactive pharmaceutical. In addition to this substance, imaging of renal function can also be performed using iodine-123-hippuran or 99mTc-diethylene-triamine-pentaacetic acid.

The process

Scintigraphic assessment of renal function can be used to indicate pathologic (disease) processes due to nuclide retention.In particular, the radiopharmaceutical 99mTc-mercapto-acetyltriglycine, which is tubularly extracted in the kidneys, makes the procedure a valuable diagnostic examination method due to its good image quality combined with low radiation exposure. As a tubular-secreted radiopharmaceutical, it images the effective renal plasma flow (represents the amount of blood cleared from the nephrons during the first passage). For optimal study results, it is necessary that renal function scintigraphy be performed immediately after intravenous administration of the radiopharmaceutical. Renal sequence (function) scintigraphy thereby allows:

  • The estimation of renal blood flow (vascular phase).
  • The visualization of functional renal parenchyma (parenchymal phase/renal tissue phase); represents the excretion of the radiopharmaceutical from the renal parenchyma via the renal pelvis and ureters/ureters into the bladder
  • Whether radioactive urine flows back from the bladder into the kidney (vesicorenal reflux).

To minimize radiation exposure after performing scintigraphy, the patient should empty his or her bladder after the examination.

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.
  • An increased risk of complications is present with combined scintigraphy with an ACE inhibitor or a diuretic (drug used to flush water out of the human body).