Dual energy CT monitoring of the renal corticomedullary sodium gradient in swine

作者：Kumar Rahi; Wang Zhen J^*; Forsythe Carlos; Fu Yanjun; Chen Yunn Yi; Yeh Benjamin M

来源：European Journal of Radiology, 2012, 81(3): 423-429.

DOI：10.1016/j.ejrad.2010.12.047

• Dual-energy CT
• Renal corticomedullary sodium gradient
• Acute tubular necrosis

Objective: To evaluate the feasibility of dual-energy CT (DECT) for monitoring dynamic changes in the renal corticomedullary sodium gradient in swine.
Material and methods: This study was approved by our Institutional Animal Care and Use Committee. Four water-restricted pigs were CT-scanned at 80 and 140 kVp at baseline and at 5 min intervals for 30 min during saline or furosemide diuresis. The renal cortical and medullary CT numbers were recorded. A DECT basis material decomposition method was used to quantify renal cortical and medullary sodium concentrations and medulla-to-cortex sodium ratios at each time point based on the measured CT numbers. The sodium concentrations and medulla-to-cortex sodium ratios were compared between baseline and at 30 min diuresis using paired Student t-tests. The medulla-to-cortex sodium ratios were considered to reflect the corticomedullary sodium gradient.
Results: At baseline prior to saline diuresis, the mean medullary and cortical sodium concentrations were 103.8 +/- 8.7 and 65.3 +/- 1.7 mmol/l, respectively, corresponding to a medulla-to-cortex sodium ratio of 1.59. At 30 min of saline diuresis, the medullary and cortical sodium concentrations decreased to 72.3 + 1.0 and 56.0 + 1.4 mmol/l, respectively, corresponding to a significantly reduced medulla-to-cortex sodium ratio of 1.29 (P < 0.05). At baseline prior to furosemide diuresis, the mean medullary and cortical sodium concentrations were 110.5 +/- 3.6 and 66.7 +/- 4.1 mmol/l, respectively, corresponding to a medulla-to-cortex sodium ratio of 1.66. At 30 min of furosemide diuresis, the medullary and cortical sodium concentrations decreased to 68.5 +/- 0.3 and 58.9 +/- 4.0 mmol/l, respectively, corresponding to a significantly reduced medulla-to-cortex sodium ratio of 1.16 (P < 0.05). One of the 4 pigs developed acute tubular necrosis likely related to prolonged hypoxia during intubation prior to the furosemide diuresis experiment. The medulla-to-cortex sodium ratio for this pig, which was excluded from the mean medulla-to-cortex ratio above, was 1.07 at baseline and 1.15 at 30 min following the administration of furosemide.
Conclusion: DECT monitoring of dynamic changes in the renal corticomedullary sodium gradient after physiologic challenges is feasible in swine. c 2011 Elsevier Ireland Ltd.

• 出版日期2012-3