Experimental study of renal damage assessment after injection of iodine contrast medium: the role of blood oxygen level-dependent functional MRI with a 3.0 T system / 中华放射学杂志

ABSTRACT

Objective To evaluate blood oxygen level-dependent (BOLD) MRI on assessing renal damage after injection of iodine contrast medium with a 3.0 T system. Methods Routine MRI examination,including T1WI and T2WI, and BOLD MRI were performed in 29 SD rats with a 3.0 T system before the injection of iodine contrast agent and 20 min, 24 h, 48 h, 72 h after the injection, respectively. T2 * and R2 * ( = 1/T2 * ) measurements were obtained in the cortex, inner and outer medulla of kidney,respectively. The results obtained before contrast agent administration were considered as the self-controls.AVONA test were used for the comparison of R2 * values in different parts of both kidneys before contrast agent administration. Two-sample t test was used to compare R2 * values before and at each time point after contrast agent administration, and R2 * values in different parts of the kidneys. Results Before contrast agentadministration, R2 * values in outer medulla in both sides of kidney [R2 *left oM = (31.76 ± 2.73 ) / s,R2 * right OM = (32.77±3.07) /s] were higher than those in cortex [R2 * left c=(30.20±3.48) /s,R2 * right c = (28.84 ±3.11 )/s] and in inner medulla [ R2 * letf IM = (29.54 ± 2.42) /s, R2 * right IM =(28.37±2.80) /s ] ( F = 3.357 and 14.961, P＜ 0.05 ). There was no statistical significance in R2 *values in the three parts between left and right kidney, including cortex, outer and inner medulla (P＞0.05). After contrast agent administration, R2* values in outer medulla changed obviously, which reached to the peak values at 20 minutes after contrast agent administration [R2* left OM = ( 43.57 ± 3.84 )/s,R2*right OM= (44.58±3.13) /s] and dropped from 24 hours [R2*left OM = (42.07 ±4.82) /s,R2* right OM = (42.89±3.40) /s]. R2* values in inner medulla and cortex only presented slight changes.Conclusion R2* values reflected the changes of oxygen content in renal cortex and medulla quantitatively,which helped for detecting medullar ischemia and hypoxia. BOLD MR imaging could offer a feasible method for evaluating oxygen metabolism and renal injury in cortex and medulla.