Evaluation of the parenchymal distribution of renal steatosis in chronic kidney disease using chemical shift magnetic resonance imaging.

Abstract

Renal steatosis is an abnormal accumulation of fat in the kidney and may cause chronic kidney disease (CKD) or CKD progression. This pilot study aimed to evaluate the quantitative measurability of the parenchymal distribution of lipid deposition in the renal cortex and medulla using chemical shift magnetic resonance imaging (MRI) and investigate its relationship with clinical stages in CKD patients. The study groups included CKD patients with diabetes (CKD-d) (n = 42), CKD patients without diabetes (CKD-nd) (n = 31) and control subjects (n = 15), all of whom underwent a 1.5T MRI of the abdomen using the Dixon two-point method. The fat fraction (FF) values in the renal cortex and medulla were calculated from measurements made on Dixon sequences, and then compared between the groups. The cortical FF value was higher than the medullary FF value in control (0.057 (0.053-0.064) compared to 0.045 (0.039-0.052)), CKD-nd (0.066 (0.059-0.071) compared to 0.063 (0.054-0.071)), and CKD-d (0.081 (0.071-0.091) compared to 0.069 (0.061-0.077)) groups (all p < 0.001). The CKD-d group cortical FF values were higher than those of the CKD-nd group (p < 0.001). The FF values began increasing at CKD stages 2 and 3, and reached statistical significance at stages 4 and 5 in CKD patients (p < 0.001). Renal parenchymal lipid deposition can be quantified separately in the cortex and medulla using chemical shift MRI. Fat accumulation occurred in cortical and medullary parenchyma in CKD patients, though predominantly in the cortex. This accumulation increased proportionally with the disease stage.