Dynamic renal scintigraphy

A practical guide for referring physicians

Principle and method

Dynamic renal scintigraphy (nephrography) is a basic functional method in nuclear medicine for evaluating perfusion, function and urine outflow from both kidneys separately.

After intravenous administration of a radiopharmaceutical (most commonly 99mTc-MAG3 for evaluating tubular secretion or 99mTc-DTPA for glomerular filtration), its distribution and elimination are monitored in real time using dynamic scintigraphy.

The results are dynamic curves (nephrograms) that reflect:

  • the blood supply to the kidney (perfusion phase),
  • the accumulation of the radiopharmaceutical in the parenchyma (secretory phase),
  • its excretion into the pelvis and ureter (excretory phase).

The examination thus provides comprehensive and quantitative information about both kidneys separately, including their relative function.

Main clinical indications

  • Evaluation of differential renal function
    • in congenital and acquired kidney diseases,
    • before unilateral nephrectomy, surgical procedures or radiotherapy.
  • Obstructive uropathy with furosemide administration
    • evidence and quantification of the significance of urinary tract obstruction,
    • assessment of the difference between obstruction and simple dilatation (hydronephrosis vs. retention).
  • Congenital developmental defects
    • Reflux nephropathy, duplication of the ureter and renal pelvis, renal ectopia.
  • Arterial hypertension
    • in combination with pharmacological intervention (captopril test) to demonstrate renovascular hypertension.
  • Acute and chronic kidney disease
    • assessment of functional reserve and renal clearance.
  • Postoperative and post-traumatic conditions
    • monitoring of transplanted kidney function,
    • follow-up after urinary tract reconstruction procedures.

Interpretation 

  • Normal findings:
    • rapid onset of perfusion, accumulation in the parenchyma and gradual excretion into the pelvis and ureter,
    • the curve has a typical shape with a rapid rise and fall.
  • Pathological findings:
    • obstruction – accumulation of radiopharmaceutical in the pelvis without subsequent elimination (so-called "obstructive renogram"),
    • parenchymal involvement – reduced accumulation and flat, slow curve progression,
    • vascular disorder – delayed perfusion phase.

Supplemented with pharmacological tests:

  • Furosemide test (F+): administration of furosemide in cases of suspected obstruction → assessment of whether the pelvis empties.
  • Captopril test: see chapter on renovascular hypertension.

Practical information for the referring physician

  • Patient preparation:
    • sufficient hydration (0.5–1 litre of fluids 30–60 minutes before the examination),
    • empty bladder,
  • Examination procedure:
    • Intravenous administration of radiopharmaceutical,
    • dynamic imaging takes 30 minutes, patient lies on their back
    • administration of furosemide (diuretic test) or enalapril (RVH provocation) as needed.
  • Radiopharmaceuticals:
    • 99mTc-MAG3 (most common),
    • 99mTc-DTPA (GFR assessment),
  • Radiation exposure: low, less than 1 mWv.
  • Contraindications: pregnancy; relative in patients unable to cooperate.

Summary for practice

Dynamic renal scintigraphy is:

  • the basic method for functional assessment of the kidneys and urinary tract,
  • indispensable in the diagnosis of obstructive uropathies,
  • valuable in determining differential renal function prior to surgical procedures,
  • useful in the diagnosis of renovascular hypertension and monitoring of transplanted kidneys,
  • safe, accessible and low in radiation exposure.

Proper indication and combination with pharmacological tests increase its informative value and significantly contribute to decisions on further procedures in nephrology and urology.