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NORA: a simple and reliable parameter for estimating renal output with or without frusemide challenge
1Department of Radioisotopes, Centre Hospitalier Universitaire St. Pierre, Brussels, Belgium.
Nuclear Medicine Communications
|June 9, 2000
Summary
This study introduces Normalized Residual Activity (NORA) as a simple, reliable parameter for quantifying renal output. NORA demonstrates a strong correlation with output efficiency and is largely independent of overall renal function.
Area of Science:
- Nuclear Medicine
- Renal Physiology
- Medical Imaging
Background:
- Assessing renal output is crucial for evaluating kidney function.
- Existing parameters for renal transit may be influenced by overall renal function.
- A simple, reliable parameter for renal output quantification is needed.
Purpose of the Study:
- To evaluate Normalized Residual Activity (NORA) as a simple parameter for renal output.
- To compare NORA with output efficiency in simulated and clinical models.
- To determine NORA's independence from renal function levels.
Main Methods:
- Simulated models using various radiotracers (123I-hippurate, 99Tcm-DTPA, 99Tcm-MAG3) and retention functions.
- Clinical study involving 33 patients, comparing NORA and output efficiency.
- NORA calculation involved normalizing residual renal activity by activity at 2 minutes post-injection.
Main Results:
- In simulations, both output efficiency and NORA showed minimal influence from varying renal function.
- A strong correlation was observed between output efficiency and NORA in the clinical study across different phases (renogram, furosemide test, post-void).
- NORA proved to be a simple and reliable measure of renal output.
Conclusions:
- Normalized Residual Activity (NORA) is a simple and reliable parameter for quantifying renal output.
- NORA is nearly independent of the level of renal function.
- NORA can be utilized effectively regardless of furosemide injection timing.