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Functional imaging of the nonhuman primate Placenta with endogenous blood oxygen level–dependent contrast
Author(s) -
Schabel Matthias C.,
Roberts Victoria H. J.,
Lo Jamie O.,
Platt Sarah,
Grant Kathleen A.,
Frias Antonio E.,
Kroenke Christopher D.
Publication year - 2016
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26052
Subject(s) - blood oxygen level dependent , placenta , endogeny , contrast (vision) , primate , nonhuman primate , biology , medicine , neuroscience , pregnancy , evolutionary biology , fetus , functional magnetic resonance imaging , computer science , artificial intelligence , genetics
Purpose To characterize spatial patterns ofT 2 *in the placenta of the rhesus macaque ( Macaca mulatta ), to correlate these patterns with placental perfusion determined using dynamic contrast‐enhanced MRI (DCE‐MRI), and to evaluate the potential for using the blood oxygen level–dependent effect to quantify placental perfusion without the use of exogenous contrast reagent. Methods MRI was performed on three pregnant rhesus macaques at gestational day 110. Multiecho spoiled gradient echo measurements were used to compute maps ofT 2 * . Spatial maxima in these maps were compared with foci of early enhancement determined by DCE‐MRI. Results Local maxima inT 2 *maps were strongly correlated with spiral arteries identified by DCE‐MRI, with mean spatial separations ranging from 2.34 to 6.11 mm in the three animals studied. Spatial patterns ofR 2 *( = 1/ T 2 * ) within individual placental lobules can be quantitatively analyzed using a simple model to estimate fetal arterial oxyhemoglobin concentration[ H b o , f]and a parameterv i P S / Φ , reflecting oxygen transport to the fetus. Estimated mean values of[ H b o , f]ranged from 4.25 mM to 4.46 mM, whereasv i P S / Φ ranged from 2.80 × 10 5 cm −3 to 1.61 × 10 6 cm −3 . Conclusions Maternal spiral arteries show strong spatial correlation with foci of extendedT 2 *observed in the primate placenta. A simple model of oxygen transport accurately describes the spatial dependence ofR 2 *within placental lobules and enables assessment of placental function and oxygenation without requiring administration of an exogenous contrast reagent. Magn Reson Med 76:1551–1562, 2016. © 2015 International Society for Magnetic Resonance in Medicine