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Pharmacological MRI of the choroid and retina: Blood flow and BOLD responses during nitroprusside infusion

Authors

  • Yen-Yu I. Shih,

    Corresponding author
    1. Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
    • Research Imaging Institute, University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Dr, San Antonio, TX 78229
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  • Guang Li,

    1. Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
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  • Eric R. Muir,

    1. Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
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  • Bryan H. De La Garza,

    1. Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
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  • Jeffrey W. Kiel,

    1. Department of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas, USA
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  • Timothy Q. Duong

    Corresponding author
    1. Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
    2. Department of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas, USA
    3. Department of Radiology, University of Texas Health Science Center, San Antonio, Texas, USA
    4. Department of Physiology, University of Texas Health Science Center, San Antonio, Texas, USA
    5. South Texas Veterans Health Care System, San Antonio, Texas, USA
    • Research Imaging Institute, University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Dr, San Antonio, TX 78229
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Abstract

Nitroprusside, a vasodilatory nitric oxide donor, is clinically used during vascular surgery and to lower blood pressure in acute hypertension. This article reports a novel application of blood flow (BF) and blood oxygenation level dependent (BOLD) MRI on an 11.7T scanner to image the rat chorioretinal BF and BOLD changes associated with graded nitroprusside infusion. At low doses (1 or 2 μg/kg/min), nitroprusside increased BF as expected but decreased BOLD signals, showing an intriguing BF–BOLD uncoupling. At high doses (3−5 μg/kg/min), nitroprusside decreased BF and markedly decreased BOLD signals. To our knowledge, this is the first pharmacological MRI application of the retina. This approach has potential to open up new avenues to study the drug-related hemodynamic functions and to evaluate the effects of novel therapeutic interventions on BOLD and BF in the normal and diseased retinas. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.

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