Relationship between renal apparent diffusion coefficient and glomerular filtration rate: preliminary study

Objective To determine the relationship between apparent diffusion coefficient (ADC) values measured by diffusion-weighted MR imaging and split renal glomerular filtration rate (GFR) determined by renal scintigraphy. Methods Diffusion-weighted echo-planar imaging (EPI) sequences with b value (0, 500 s/mm 2) were performed in 55 patients whose split renal GFR were measured by 99 Tc m-DTPA scintigraphy. The whole kidney ADC was calculated and the 110 kidneys were divided into 4 groups: Group 1 (normal renal function, n=44), GFR≥34 ml/min; Group 2 (mild renal impairment, n=36), 34GFR≥20 ml/min; Group 3 (moderate renal impairment, n=21), 20GFR≥10 ml/min; Group 4 (severe renal impairment, n=9), GFR10 ml/min. Differences between the 4 groups respect to the mean renal ADCs and the correlation of the renal ADC value and GFR were analyzed. Results There was statistically significant difference in renal ADCs among the 4 groups. The ADC of kidney showed positive linear correlation with GFR (r=0.709). Conclusion The ADC values of impaired kidneys were significantly lower than those of normal. DWI may be useful to evaluate renal function.