PURPOSE: To determine whether MRI in combination with an intravascular contrast agent is sensitive to pharmacologically induced vasodilation and vasoconstriction in the rat kidney. MATERIALS AND METHODS: R(2) imaging was performed in 25 Sprague Dawley rats at 3 Tesla in the presence of ferumoxytol, an ultrasmall superparamagnetic iron oxide (USPIO) agent with a long plasma half-life. R(2) changes were measured following manipulation of blood volume by intravenous administration of adenosine, a short-acting vasodilator, or N(G)-nitro-L-arginine methyl ester (L-NAME), a long-acting nitric oxide synthase inhibitor with known vasoconstrictive effects. As a control, R(2) responses to adenosine and L-NAME were also examined in the absence of ferumoxytol. RESULTS: In the presence of ferumoxytol, adenosine induced a significant increase in R(2), while L-NAME produced a reduction, although the latter was not statistically significant. Control experiments revealed small R(2) changes in the absence of ferumoxytol. An incidental finding was that the cross-sectional area of the kidney also varied dynamically with adenosine and L-NAME. CONCLUSION: Our results suggest that ferumoxytol-enhanced R(2) imaging is sensitive to adenosine-induced vasodilation. The responses to L-NAME, however, were not statistically significant. The variations in kidney size and the R(2) changes in the absence of ferumoxytol may reflect alterations in the volume of the renal tubules.
PURPOSE: To determine whether MRI in combination with an intravascular contrast agent is sensitive to pharmacologically induced vasodilation and vasoconstriction in the rat kidney. MATERIALS AND METHODS: R(2) imaging was performed in 25 Sprague Dawley rats at 3 Tesla in the presence of ferumoxytol, an ultrasmall superparamagnetic iron oxide (USPIO) agent with a long plasma half-life. R(2) changes were measured following manipulation of blood volume by intravenous administration of adenosine, a short-acting vasodilator, or N(G)-nitro-L-arginine methyl ester (L-NAME), a long-acting nitric oxide synthase inhibitor with known vasoconstrictive effects. As a control, R(2) responses to adenosine and L-NAME were also examined in the absence of ferumoxytol. RESULTS: In the presence of ferumoxytol, adenosine induced a significant increase in R(2), while L-NAME produced a reduction, although the latter was not statistically significant. Control experiments revealed small R(2) changes in the absence of ferumoxytol. An incidental finding was that the cross-sectional area of the kidney also varied dynamically with adenosine and L-NAME. CONCLUSION: Our results suggest that ferumoxytol-enhanced R(2) imaging is sensitive to adenosine-induced vasodilation. The responses to L-NAME, however, were not statistically significant. The variations in kidney size and the R(2) changes in the absence of ferumoxytol may reflect alterations in the volume of the renal tubules.
Authors: Feng Wang; Rosie T Jiang; Mohammed Noor Tantawy; Dorin B Borza; Keiko Takahashi; John C Gore; Raymond C Harris; Takamune Takahashi; C Chad Quarles Journal: J Magn Reson Imaging Date: 2013-09-04 Impact factor: 4.813
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Authors: Pierre-Hugues Vivier; Pippa Storey; Hersh Chandarana; Akira Yamamoto; Kristopher Tantillo; Umer Khan; Jeff L Zhang; Eric E Sigmund; Henry Rusinek; James S Babb; Michael Bubenheim; Vivian S Lee Journal: Invest Radiol Date: 2013-07 Impact factor: 6.016
Authors: Pottumarthi V Prasad; Jon Thacker; Lu-Ping Li; Muhammad Haque; Wei Li; Heather Koenigs; Ying Zhou; Stuart M Sprague Journal: PLoS One Date: 2015-10-02 Impact factor: 3.240