Measurement of Glomerular Filtration Rate With Contrast-enhanced Dynamic MR Imaging in Renal Transplant Recipients: Evaluation of the Agreement With the Cr51 -EDTA Method and of Reproducibility

Cr51- EDTA method is considered the reference method for measurement of glomerular filtration rate (GFR). However, this method requires several hours and several blood and urinary samplings. Therefore, the ability to get access to this parameter with a simple, valid and reliable method would be a significant progress in clinical follow-up of patients with renal disease. Contrast-enhanced dynamic MRI is now able to give this access to functional parameters as GFR, rapidly and non invasively, becoming an alternative to Cr51-EDTA method. If the acquisition method has been optimized, some problems remain unsolved: is the movement correction worthwhile for the accuracy of the measurement ? Which model provides the most accurate results ? What is the best way to calculate the total GFR (addition of all the voxels or the product of a mean value by the cortical volume)? These questions can be answered only by a comparison with a reference method.

The reference method will be performed after standard hydration, with intravenous injection of 100 µCi of Cr51- EDTA and urinary and blood samplings every 30 minutes during 3h. Dynamic MRI will be performed with fast 3D T1-weighted gradient-echo sequences during 5 minutes after injection of a third of a clinical dose of gadolinium. Post-treatment of images will be done on an off-line program allowing movement correction, conversion of signal intensity into concentration and application of different models. 8 combinations of post-treatment will be tested and compared to the reference method.