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This Article Full Text Full Text (PDF) All Versions of this Article: 297/5/F1288    most recent 00388.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Atthe, B. K. Articles by Bansal, N. PubMed PubMed Citation Articles by Atthe, B. K. Articles by Bansal, N.

Early monitoring of acute tubular necrosis in the rat kidney by ²³Na-MRI

¹Departments of Radiology, ; ²Biomedical Engineering, ; ³Pathology and Laboratory Medicine, and ; ⁴Medicine, Indiana University-Purdue University at Indianapolis, Indianapolis; and ; ⁵Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana

Submitted July 9, 2009 ; accepted in final form August 18, 2009

Reabsorption of water and other molecules is dependent on the corticomedullary sodium concentration gradient in the kidney. During the early course of acute tubular necrosis (ATN), this gradient is altered. Therefore, ²³Na magnetic resonance imaging (MRI) was used to study the alterations in renal sodium distribution in the rat kidney during ischemia and reperfusion (IR) injury, which induces ATN. In-magnet ischemia was induced for 0 (control), 10, 20, 30 or 50 min in Wistar rats. ²³Na images were collected every 10 min during baseline, ischemia, and 60-min reperfusion periods. T₁ and T₂ relaxation times were measured by both ²³Na-MRI and -MRS on a separate cohort of animals during ischemia and reperfusion for correction of relaxation-related tissue sodium concentration (TSC). A marked decrease was observed in the medulla and cortex ²³Na-MRI signal intensity (SI) during the early evolution of ATN caused by IR injury, with the sodium reabsorption function of the kidney being irreversibly damaged after 50 min of ischemia. Sodium relaxation time characteristics were similar in the medulla and cortex of normal kidney, but significantly decreased with IR. The changes in relaxation times in both compartments were identical; thus the medulla-to-cortex sodium SI ratio represents the TSC ratio of both compartments. The extent of IR damage observed with histological examination correlated with the ²³Na-MRI data. ²³Na-MRI has great potential for noninvasive, clinical diagnosis of evolving ATN in the setup of acute renal failure and in differentiating ATN from other causes of renal failure where tubular function is maintained.

ischemia-reperfusion injury; relaxation times; tissue; sodium concentration