Relationship between blood and myocardium manganese levels during manganese‐enhanced MRI (MEMRI) with T1 mapping in rats |
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| Authors: | Tom C‐C Hu Kai‐Hsiang Chuang Nathan Yanasak Alan Koretsky |
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| Affiliation: | 1. Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA;2. Small Animal Imaging, Department of Radiology, Medical College of Georgia, Augusta, GA, USA |
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| Abstract: | Manganese ions (Mn2+) enter viable myocardial cells via voltage‐gated calcium channels. Because of its shortening of T1 and its relatively long half‐life in cells, Mn2+ can serve as an intracellular molecular contrast agent to study indirect calcium influx into the myocardium. One major concern in using Mn2+ is its sensitivity over a limited range of concentrations employing T1‐weighted images for visualization, which limits its potential in quantitative techniques. Therefore, this study assessed the implementation of a T1 mapping method for cardiac manganese‐enhanced MRI to enable a quantitative estimate of the influx of Mn2+ over a wide range of concentrations in male Sprague‐Dawley rats. This MRI method was used to compare the relationship between T1 changes in the heart as a function of myocardium and blood Mn2+ levels. Results showed a biphasic relationship between ΔR1 and the total Mn2+ infusion dose. Nonlinear relationships were observed between the total Mn2+ infusion dose versus blood levels and left ventricular free wall ΔR1. At low blood levels of Mn2+, there was proportionally less cardiac enhancement seen than at higher levels of blood Mn2+. We hypothesize that Mn2+ blood levels increase as a result of rate‐limiting excretion by the liver and kidneys at these higher Mn2+ doses. Copyright © 2010 John Wiley & Sons, Ltd. |
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| Keywords: | T1 mapping cardiac MRI rat heart manganese imaging |
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