Yi Zhang1, Oscar San Emeterio Nateras2,
Qi Peng1,2, Carlos A. Rosende3, John M. Johnson4,
Timothy Q. Duong1,2
1Research Imaging
Institute, University of Texas Health Science Center at San Antonio, San
Antonio, TX, United States; 2Radiology, University of Texas Health
Science Center at San Antonio, San Antonio, TX, United States; 3Ophthalmology,
University of Texas Health Science Center at San Antonio, San Antonio, TX,
United States; 4Physiology, University of Texas Health Science
Center at San Antonio, San Antonio, TX, United States
This study investigated the relation between perfusion pressure and blood flow (BF) in the human retina using MRI during rest and isometric exercise (squeezing a tennis ball inside the MRI scanner). Basal BF in the posterior retina was 13747mL/100mL/min (SD, N=4). Isometric exercise increased mean BF, heart rate, mean arterial pressure, and ocular perfusion pressure (P<0.05), but not intraocular pressure, arterial oxygen saturation, end-tidal carbon dioxide, or respiratory rate (P>0.1). A MRI approach provides objective quantitative BF with a large field of view without depth limitation. BF MRI during isometric exercise provides a unique means to study retinal physiology and autoregulation free of adverse pharmacological effects.
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