R1 changes in the human placenta at 3 T in response to a maternal oxygen challenge protocol

Ingram, Emma; Hawkins, Lauren; Morris, David; Myers, Jenny; Sibley, Colin P.; Johnstone, Edward; Naish, Josephine H.

doi:10.1016/j.placenta.2016.01.016

Cited by 13 publications

(19 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A constrained background suppression scheme, which applied nonselective inversion pulses within the PLD, was implemented for this study to keep the labeling scheme intact. Although placenta was reported to have longer T 1 values than the 1400-1700 msec optimization range used in this study, 30 a similar background suppression effect is achievable for PLDs from 1000-2000 msec, as reported in our previous research. 14 To ensure the accuracy for ATT estimation, the labeling plane was placed at the aortic bifurcation, which is easy to identify compared to tortuous uterine arteries, by trained MR technicians and research fellows.…”

Section: Discussionsupporting

confidence: 87%

Measuring human placental blood flow with multidelay 3D GRASE pseudocontinuous arterial spin labeling at 3T

Shao

Liu

Martin

et al. 2017

Magnetic Resonance Imaging

View full text Add to dashboard Cite

show abstract

Section: Discussionsupporting

confidence: 87%

Measuring human placental blood flow with multidelay 3D GRASE pseudocontinuous arterial spin labeling at 3T

Shao

Liu

Martin

et al. 2017

Magnetic Resonance Imaging

View full text Add to dashboard Cite

show abstract

“…In ASL FAIR, and ASL generally, for any signal difference to occur, spins must travel from the labeling region to the imaging voxel within a postlabel delay period. In this work, this delay was 2 seconds, a typical value used for ASL at 3 T. Extending the postlabel delay would theoretically allow for ASL with reduced transit‐time dependence but with the tradeoff that the magnetic‐inversion label will decay exponentially according to the T 1 of blood (T 1 = approximately 1.6 seconds at 3 T) degrading SNR.…”

Section: Discussionmentioning

confidence: 99%

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

Ludwig

Fain

Nguyen

et al. 2018

Magnetic Resonance in Med

View full text Add to dashboard Cite

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.

show abstract

“…It is thus an obvious candidate for assessing placental function in a range of other placental conditions . Extensive recent work has also been carried out investigating T1 relaxometry and T2* relaxometry, which is intrinsically linked to blood oxygenation . Notably, there is a high spatial variability in placental T2* maps that has been observed, which corresponds to the known macroscopic lobular structure of the placenta and its division into discrete functional units.…”

Section: Introductionmentioning

confidence: 99%

Separating fetal and maternal placenta circulations using multiparametric MRI

Melbourne

Aughwane

Sokolska

et al. 2018

Magnetic Resonance in Med

127

View full text Add to dashboard Cite

PurposeThe placenta is a vital organ for the exchange of oxygen, nutrients, and waste products between fetus and mother. The placenta may suffer from several pathologies, which affect this fetal‐maternal exchange, thus the flow properties of the placenta are of interest in determining the course of pregnancy. In this work, we propose a new multiparametric model for placental tissue signal in MRI.MethodsWe describe a method that separates fetal and maternal flow characteristics of the placenta using a 3‐compartment model comprising fast and slowly circulating fluid pools, and a tissue pool is fitted to overlapping multiecho T2 relaxometry and diffusion MRI with low b‐values. We implemented the combined model and acquisition on a standard 1.5 Tesla clinical system with acquisition taking less than 20 minutes.ResultsWe apply this combined acquisition in 6 control singleton placentas. Mean myometrial T2 relaxation time was 123.63 (±6.71) ms. Mean T2 relaxation time of maternal blood was 202.17 (±92.98) ms. In the placenta, mean T2 relaxation time of the fetal blood component was 144.89 (±54.42) ms. Mean ratio of maternal to fetal blood volume was 1.16 (±0.6), and mean fetal blood saturation was 72.93 (±20.11)% across all 6 cases.ConclusionThe novel acquisition in this work allows the measurement of histologically relevant physical parameters, such as the relative proportions of vascular spaces. In the placenta, this may help us to better understand the physiological properties of the tissue in disease.

show abstract

R1 changes in the human placenta at 3 T in response to a maternal oxygen challenge protocol

Cited by 13 publications

References 9 publications

Measuring human placental blood flow with multidelay 3D GRASE pseudocontinuous arterial spin labeling at 3T

Measuring human placental blood flow with multidelay 3D GRASE pseudocontinuous arterial spin labeling at 3T

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

Separating fetal and maternal placenta circulations using multiparametric MRI

Contact Info

Product

Resources

About