Purpose: Study of the kidney by apparent diffusion coefficient (ADC) measurements is interesting because of the organ's high blood flow and water transport functions. We investigated the relationship between ADC values of the kidney and the estimated glomerular filtration rate (eGFR).
Methods: We retrospectively evaluated 180 patients (113 men, 67 women, aged 20 to 89 years, mean age, 61.06 years) who underwent abdominal magnetic resonance (MR) imaging at 1.5 tesla. Transverse multisection echo-planar diffusion-weighted imaging (DWI) was performed using diffusion gradient b-values of 50 and 1000 s/mm(2). Regions of interests (ROIs) were manually delineated in the parenchyma as large as possible at the level of the middle portion of the bilateral kidneys. For each kidney, 2 nonoverlapping ROIs were placed at different locations; 4 total ROIs from the bilateral kidneys were averaged for each patient. ADC values were measured directly from the ROIs. The eGFR was calculated by an equation based on serum creatinine level. The patients were divided into 3 groups: eGFR<30 mL/min/1.73 m(2); 30<==eGFR<60; and 60<==eGFR.
Results: The mean ADC values of the 3 groups were 1.71+/-0.18 for the group with eGFR<30 mL/min/1.73 m(2); 1.87+/-0.11 for those with eGFR>or=30; and 1.88+/-0.12x10(-3) mm(2)/s for those with eGFR>or=60. The mean ADC values were significantly lower in the patients with eGFR<30 than in the other groups (P<0.05); no difference was found between the other groups; and there was no statistically significant correlation between mean ADC and eGFR values.
Conclusion: Patients with low eGFR tended to have lower ADC values. However, this study failed to show significant correlation between mean ADC values and eGFR.