Perfusion of the placenta assessed using arterial spin labeling and ferumoxytol dynamic contrast enhanced magnetic resonance imaging in the rhesus macaque

• Published in: Magnetic resonance in medicine 2019-03, Vol.81 (3), p.1964-1978
• Main Authors: Ludwig, Kai D., Fain, Sean B., Nguyen, Sydney M., Golos, Thaddeus G., Reeder, Scott B., Bird, Ian M., Shah, Dinesh M., Wieben, Oliver E., Johnson, Kevin M.
• Format: Article
• Language: English
• Subjects: Amniotic fluid; Animals; arterial spin labeling; Arteries; Arteries - diagnostic imaging; Contrast Media; Cytokines; dynamic contrast enhanced; Female; Ferrosoferric Oxide - analysis; ferumoxytol; Fetuses; Image Processing, Computer-Assisted; Inflammation; Interleukin-1beta - metabolism; Interleukins; intervillous perfusion; Labeling; Macaca mulatta; Magnetic Resonance Angiography; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; NMR; Nuclear magnetic resonance; Perfusion; Placenta; Placenta - diagnostic imaging; Placenta - pathology; Pregnancy; Pregnancy, Animal; rhesus macaque; Saturation; Spin dynamics; Spin labeling; Spin Labels; Travel time
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.27548

Purpose To investigate the correspondence between arterial spin labeling (ASL) flow‐sensitive alternating inversion recovery (FAIR) and ferumoxytol DCE MRI for the assessment of placental intervillous perfusion. Methods Ten pregnant macaques in late second trimester were imaged at 3 T using a 2D ASL FAIR, with and without outer‐volume saturation pulses used to control the bolus width, and a 3D ferumoxytol DCE‐MRI acquisition. The ASL tagged/control pairs were averaged, subtracted, and normalized to create perfusion ratio maps. Contrast arrival time and uptake slope were estimated by fitting the DCE data to a sigmoid function. Macaques (N = 4) received interleukin‐1β to induce inflammation and disrupt perfusion. Results The FAIR tag modification with outer‐volume saturation reduced the median ASL ratio percentage compared with conventional FAIR (0.64% ± 1.42% versus 0.71% ± 2.00%; P < .05). Extended ferumoxytol arrival times (34 ± 25 seconds) were observed across the placenta. No significant DCE signal change was measured in fetal tissue (−0.6% ± 3.0%; P = .52) or amniotic fluid (1.9% ± 8.8%; P = .59). High ASL ratio was significantly correlated with early arrival time and high uptake slope (P < .05), but ASL signal was not above noise in late‐DCE‐enhancing regions. No significant differences were observed in perfusion measurements between the interleukin‐1β and controls (P > .05). Conclusion The ASL‐FAIR and ferumoxytol DCE‐MRI methods are feasible to detect early blood delivery to the macaque placenta. Outer volume saturation reduced the high macrovascular ASL signal. Interleukin‐1β exposure did not alter placental intervillous perfusion. An endogenous‐labeling perfusion technique is limited due to extended transit times for flow within the placenta beyond the immediate vicinity of the maternal spiral arteries.