A prospective comparison of dynamic contrast-enhanced MRI and ⁵¹Cr-EDTA clearance for glomerular filtration rate measurement in 42 kidney transplant recipients

Objectives: To evaluate the performance of dynamic contrast-enhanced MRI measurement of glomerular filtration rate (GFR) compared with the reference standard technique of urinary clearance of ⁵¹Cr-EDTA.

Patients and methods: All kidney transplant recipients (KTRs) with an indication for non-urgent contrast-enhanced MRI at our institution were prospectively included between 2008 and 2012. Renographies were acquired by low-dose dynamic contrast-enhanced MRI (DCE-MRI) then fitted with a two-compartment pharmacokinetic model. MR-GFR was compared with reference isotopic measurements using Bland-Altman diagrams, intraclass correlation coefficient (ICC) and concordance rates.

Results: Forty-two KTRs (mean age 51.5 years, 26-74) were analyzed. Mean estimated GFR was 48.5 ± 27 mL/min/1.73m² (24-178 mL/min). The mean bias was +13.2 mL/min (6.4-20.0, +36.9%) ranging from -31.0 mL/min (-41.7%) to +101.4 mL/min (+89.2%) with a large variability (standard-deviation: 22.3 mL/min; limits of agreement: [-30.6 (-43.3--18.9); +57.0 (45.3-68.7)]). The ICC was 0.32 (0.02-0.56) and the concordance rate was 28.6% (14.9-42.2).

Conclusions: The large variability of MR-GFR compared with the reference technique precludes its use in KTRs, whose anatomical peculiarities make standardization of arterial input function (AIF) difficult.