Diffusion-weighted magnetic resonance imaging in the evaluation of renal function: a preliminary study

Abstract

Purpose: Magnetic resonance diffusion-weighted imaging (MR-DWI) is useful to assess proton motion by the computation of an apparent diffusion coefficient (ADC). This property could be used to assess renal damage, with special regard to unilateral dysfunction. The aim of this study was to estimate the correlation between ADC and the stage of chronic renal failure (CRF) using a spin-echo echo-planar imaging (SE-EPI) sequence with the sensitivity encoding (SENSE) technique.

Materials and methods: Fourteen patients (nine men and five women, mean age 49 years, range 22-66 years) underwent an MR examination on a 1.5-T system. Seven patients had a history of hypertension or CRF, one had Takayasu disease and one had nephrovascular hypertension. Five subjects without known kidney disease were used as controls. The glomerular filtration rate (GFR) assessed by Cockcroft-Gault's equation was used as a functional marker. The imaging protocol consisted of T1- and T2-weighted sequences followed by a SE-EPI acquisition with a diffusion gradient of 600 s/mm(2) and SENSE factor 2 and pixel-by-pixel ADC map reconstruction. In five patients, the SE-EPI-DWI sequence was repeated after i.v. administration of 1 mg of furosemide.

Results: ADC was of 2.44+/-0.24 x 10(-3) mm(2)/s in patients with normal GFR and of 2.05+/-0.33 x 10(-3) mm(2)/s (p<0.05) in subjects with altered GFR; a significant difference was found between stage III and IV (p<0.01), whereas no differences were found between stage I and II (p=0.27) and between stage II and III (p=0.39). A good correlation was found between GFR and ADC (r=0.79; p<0.01), with no significant change after furosemide administration (p=0.7).

Conclusions: DWI is a feasible MR technique for assessing renal damage. Further studies with scintigraphic correlation are needed to confirm these results and to establish reference values for this imaging technique.