Mercuric Chloride-Induced Acute Tubular Necrosis in the Rabbits: Gd-DTPA Enhanced Dynamic IVIR Imaging

ABSTRACT

PURPOSE: To evaluate potential usefulness of dynamic Gd-DTPA enhanced MRI in the diagnosis of HgCI2 induced acute tubular necrosis of rabbits. MATERIALS AND METHODS: Sixteen rabbits were used as control group, and 14 rabbits and 12 rabbits were used as acute tubular necrosis groups of 24 hours and 48 hours after HgCI2 injection, respectively. Sequential dynamic MR imagings were acquired using Gd-DTPA(0.25mmol/kg), and time-signal intensity curves were obtained from cortex, outer medulla and inner medulla. RESULTS: In control group, a dark band, which reflects concentrated Gd-DTPA, migrated from cortex to inner medulla of the kidney, and the ratio of the signal intensity of post Gd-DTPA injection to the signal intensity of pre Gd-DTPA injection(RSI) decreased below 1 at 13sec and 26sec (mean17 +/- 6.2sec) in cortex, at 52sec (mean52sec) in outer medulla, and after 117sec(mean112 +/- 33.9sec) in inner medulla of the kidney. In acute tubular necrosis group of 24 hours after HgCI2 injection, the dark band did not appear and signal intensity in cortex and medulla increased diffusely, and RSI increased above 1 in all locations. In acute tubular necrosis group of 48 hours after HgCI2 injection, the dark band appeared only in the cortex and no sign of migration was observed, and RSI is little changed except in cortex at 13sec(0.76 +/- 0.05) and 26sec(0.86 +/- 0.06). There were statistically significant differences in the time-RSI curves among cortex, outer medulla, and inner medulla in study groups, respectively (p<0.0001). CONCLUSION: Dynamic Gd-DTPA enhanced MRI of the kidney could be utilized to evaluate both renal structure and functional changes.