Measurement of Glomerular Filtration Rate With Magnetic Resonance Imaging: Principles, Limitations, and Expectations
Résumé
Glomerular filtration rate (GFR) is the most useful quantitative index of renal function and is used clinically as the gold standard of renal dysfunction. Follow-up of patients with impaired renal function requires reliable measurements of GFR. Thus, serial GFR values estimated from magnetic resonance imaging (MRI) would be worthwhile if easy to obtain, accurate, and reproducible. Nuclear medicine-based techniques remain at present the reference method for quantification of GFR, but MRI should be able to compete in the near future. Several methods are available for measurement of GFR using MRI and freely filtered Gd-chelates: (1) measurement of the clearance of the agent using blood samplings; (2) measurement of the clearance of the agent using signal intensity changes within abdominal organs; (3) measurement of the extraction fraction of the agent; and (4) monitoring of tracer intrarenal kinetics. A high heter-ogeneity of protocols (e.g., in acquisition mode, dose of contrast, postprocessing techniques) is noted in the literature, reflecting the number of technical challenges that will have to be solved before to reach a consensus, and the reported accuracy and reproducibility are insufficient for justifying their use in clinical practice now.
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