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Eur J Radiol. 2012 Mar;81(3):423-9. doi: 10.1016/j.ejrad.2010.12.047. Epub 2011 Jan 14.

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

Author information

  • 1Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Avenue, San Francisco, CA 94143-0628, United States.

Abstract

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.

Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

PMID:
21237601
[PubMed - indexed for MEDLINE]
PMCID:
PMC4130239
Free PMC Article

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