Pitfalls and Limitations of Radionuclide Renal Imaging in Adults
Section snippets
Applied Physiology of the Kidney
To understand the pitfalls and limitations of renal imaging with radionuclides, it is essential to understand the relevant physiology of the kidney.
For a standard-sized adult, renal blood flow is approximately 500 mL/min per kidney, which is approximately 20% of cardiac output. Renal perfusion is 300-350 mL/min/100 g. The blood volume of a single kidney is approximately 50 ml. Renal plasma flow (RPF) is 250-300 mL/min per kidney. Glomerular filtration rate (GFR) is 50-60 mL/min per kidney, so
Pharmacokinetics of Radiopharmaceuticals for Imaging the Kidneys
For dynamic imaging:
Tc-99m-diethylene triamine pentaacetic acid (DTPA) (Pentatate; 492 Da)
Tc-99m-MAG3 (Mertiatide; 350 Da)
For static imaging:
Tc-99m-dimercaptosuccinic acid (DMSA) (Succimer; 281 Da)
Tc-99m-DTPA, like inulin, circulates in blood with negligible binding to plasma proteins and does not penetrate red cells. It is freely filtered at the glomerulus. As a small hydrophilic molecule, Tc-99m-DTPA crosses capillary endothelium throughout the body by passive diffusion between the
Native Kidneys
The patient should be well hydrated and have recently voided. The supine position, with the gamma camera under the imaging couch, is the most comfortable for the patient. Some departments image patients in a semi-recumbent or even sitting position to promote drainage from the renal collecting systems but this is an awkward position for the patient to maintain and is therefore prone to movement artefact. In any event, it should be routine practice to take the patient from the imaging couch at
Indications for Renal Scintigraphy in Adults
A useful general rule in deciding between dynamic and static renal imaging in a particular clinical scenario is to choose DMSA, which is best for relative function and focal cortical loss, unless information is required of renal blood flow and outflow tract drainage, or both.
Dynamic Renal Imaging
It is helpful to approach the study by interpreting the 3 phases of the renogram, in order.
Conclusion
Renal imaging remains an important subspecialty in nuclear medicine. In the era of hybrid imaging in which anatomy is all important, a proper understanding of renal imaging, including an appreciation of pitfalls and limitations, requires a sound basing in applied physiology, the classical benchmark of nuclear medicine.
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Semin Nucl Med
(1999) Pitfalls and limitations of radionuclide renal imaging in pediatrics
Semin Nucl Med
(2015)- et al.
Extracellular fluid volume and glomerular filtration rate in 1878 healthy potential renal transplant donors: Effects of age, gender, obesity and scaling
Nephrol Dial Transplant
(2012)