In vivo evaluation of renal function using diffusion weighted imaging and diffusion tensor imaging in type 2 diabetics with normoalbuminuria versus microalbuminuria.

This work aims to estimate the value of diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) in detecting early-stage kidney injury in type 2 diabetic patients with normoalbuminuria (NAU) versus microalbuminuria (MAU) prospectively. A total of 30 T2DM patients with normal kidney function were recruited and assigned to the NAU group (n = 14) or MAU group (n = 16) according to 8 h overnight urinary albuminuria excretion rate (AER) results. A contemporary cohort of health check-up recipients were included as controls (n = 12). DWI and DTI scans were performed on bilateral kidney using SE single-shot EPI, and apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the renal parenchyma was determined from ADC and FA maps of the three groups. ADC and FA values were compared among the three groups. According to DWI with a b value of 400 s/mm(2), the MAU and NAU groups showed significantly lowered mean ADC values compared with the healthy controls (P < 0.01). The mean ADC in the MAU group [(2.22 ± 0.07) × 10(-3)mm(2)/s] was slightly lower than that of the NAU group [(2.31 ± 0.22) × 10(-3)mm(2)/s], but this difference was not statistically significant (P > 0.05). The FA value in the MAU group was higher than that in the control group (0.45 ± 0.07 vs. 0.39 ± 0.03, P = 0.004) but did not differ from that in the NAU group (0.42 ± 0.03) (P > 0.05). ADC and FA values may be more sensitive than urine AER in reflecting early-stage kidney injury and, hence, may facilitate earlier detection and quantitative evaluation of kidney injury in T2DM patients. Combined evaluation of ADC and FA values may provide a better quantitative approach for identifying diabetic nephropathy at early disease stages.