MR determination of glomerular filtration rate in subjects with solitary kidneys in comparison to clinical standards of renal function: feasibility and preliminary report. 
This study was conducted to demonstrate the feasibility of quantifying single kidney glomerular filtration rate (skGFR) by magnetic resonance (MR) by comparison to the clinical estimates of GFR in volunteer subjects with a single kidney.  Seven IRB-approved subjects with a solitary kidney, stable serum creatinine (SCr) and a 24 h creatinine clearance (CrCl) volunteered to undergo an MR examination that determined renal extraction fraction (EF) with a breathhold inversion recovery echo planar pulse sequence and renal blood flow with a velocity encoded phase imaging sequence.  The product of EF and blood flow determines GFR.  These values were compared with the 24 h CrCl, estimated GFR by the modification of diet in renal disease (MDRD) regression analysis and the Cockroft-Gault (CG) determination of CrCl.  The mean and standard deviation of differences between the MR GFR, MDRD and CG vs the 24 h CrCl were 12.3+/-35.7, -8.9+/-18.5 and 1.2+/-19.6, respectively.  The Student t-test showed that none of the mean differences were statistically significant between techniques.  This clinical investigation shows that MR can be used for skGFR determination in human subjects with comparable values to those derived from clinically used serum-based GFR estimation techniques.