 MRI based assessment of GFR and RBF have been suggested to provide reasonable accuracy. Most of these studies did not compare the GFR and RBF estimation directly to Inulin and PAH clearance which are ther gold standards . In this study we propose to estimate MRI based GFR estimation directly to Inulin and noncontrast MRI based derived RBF to PAH to assess if MRI is an accurate test of kidney function. 