Value of susceptibility weighted imaging in evaluating renal excess iron deposition / 中华放射学杂志

ABSTRACT

Objective:To explore the value of susceptibility weighted imaging (SWI) in evaluating renal excess iron deposition.Methods:Thirty New Zealand white rabbits were randomly divided into iron group (injected iron dextran) with 15 rabbits and control group with 15 rabbits. All rabbits underwent SWI examination at 0th week before and 8th week after the injection of iron. MRI images of the control and iron group at the 0th and 8th week were analyzed. The phase value of renal cortex was measured on the phase images and the angle radian value was calculated. The distribution of renal iron deposition was observed by Prussian blue stain. The renal iron content was measured by atomic absorption spectrophotometer. The Mann-Whitney U or Wilcoxon test was used to compare the difference in angular radian value between the two groups. The independent sample t test was used to compare the difference in renal iron content between the two groups. Results:Only in iron group at 8th week, the SWI signal intensity of renal cortex was significantly lower than that of medulla. The renal cortical SWI signal intensity of iron group at 8th week was significantly lower than that of iron group at 0th week and control group at 8th week, respectively. The angle radian value of iron group at 8th week [0.202 3(0.161 8, 0.272 5)] was significantly higher than that of iron group at 0th week [-0.045 4 (-0.013 9, 0.008 0)] and control group at 8th week [-0.011 2 (-0.052 9, -0.001 4)], respectively ( Z=-3.408, -4.666, all P<0.05). Only in the iron group at 8th week, the obvious blue iron deposition were observed in renal cortex and few were observed in medulla. The renal iron content [(135.3±14.1) mg/kg] of iron group at 8th week was significantly higher than that [(75.5±9.8) mg/kg] of control group at 8th week ( t=13.938, P<0.001). Conclusions:SWI can evaluate the excess iron deposition in kidney. Excess iron is mainly deposited in the renal cortex and reduces its SWI signal intensity. The angle radian value calculated from the phase value can quantify the iron deposition.