To evaluate the value of blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) in the assessment of renal oxygenation of patients with type 2 diabetes mellitus (T2DM).

From April 2014 to October 2015, kidney scans were conducted in eighteen patients with T2DM and twenty-two healthy controls with a Philips 3.0T scanner by using a BOLD-MRI sequence. The medullary and cortical apparent relaxation rate(R2^*)values were measured in both groups. Paired samples t-test and independent samples t-test were used in data comparison within or between groups. The correlation between the renal glomerular filtration rate estimated using cystatin C(CysC-GFR) and the R2^* values was analyzed by Pearson correlation coefficient analysis.

The medullary R2^* values were significantly higher than those of cortex in both groups (t=21.5, 21.1, both P<0.01). The cortex R2^* values in patients with T2DM and healthy controls were (15.3±1.9) and (15.0±1.7) 1/s respectively, and there was no significant differences between two groups (t=0.7, P>0.05). The medullary R2^* values in the patients with T2DM and healthy controls were (38.1±4.1) and (29.6±2.7) 1/s respectively, it was significantly higher in the type 2 diabetic patients than that in healthy controls (t=8.0, P<0.01). Medullary R2^* value had a high sensitivity (83.33%) and specificity (100%) in identifying patients with T2DM with an area under the receiver operating characteristic curve of 0.965, and the best testing threshold was 34.1 1/s. The medullary R2^* value was found positively correlated with CysC-GFR level in patients with T2DM (r=0.7, P<0.01), but no correlation was found between the cortical R2^* value and CysC-GFR (r=0.1, P>0.05).

BOLD-MRI can detect and assess the renal medullary hypoxia in patients with T2DM at the early stage, and medullary R2^* value may reflect the changes of renal function.

Diabetes mellitus, type 2; Renal function; Blood oxygen level-dependent magnetic resonance imaging