Assessing within‐subject rates of change of placental MRI diffusion metrics in normal pregnancy

Abstract

Studying placental development informs when development is abnormal. Most placental MRI studies are cross-sectional and do not study the extent of individual variability throughout pregnancy. We aimed to explore how diffusion MRI measures of placental function and microstructure vary in individual healthy pregnancies throughout gestation. Methods: Seventy-nine pregnant, low-risk participants (17 scanned twice and 62 scanned once) were included. T 2 -weighted anatomical imaging and a com-This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Advanced magnetic resonance imaging detects altered placental development in pregnancies affected by congenital heart disease

“…As expected, we show that placental volume increases with advancing gestation. Consistent with previous work, we also identify a decrease in both T2* and ADC values with advancing gestations 39,40,62 , which appear consistent in healthy participants undergoing two scans 63 .…”

“…The acquired data were then anonymised and reconstructed using in-house tools, including denoising and motion-correction, as previously described 49 . The reproducibility of this T2*-diffusion sequence has been demonstrated in MR phantom, adult brain, and placental studies 49,63 .…”

“…The T2*-ADC model described in Eq. ( 1 ) was then fit voxelwise using a modified version of the diffusion microstructure imaging in python toolbox 77 , as described in 63 , enabling calculation of the mean T2* and ADC values for the whole ROI.

Figure 6 Data flow.

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Placental T2* as a measure of placental function across field strengths: Normal values from 0.55T to 3T.

“…Most studies evaluate mean T2* over the entire organ with some variation in terms of coverage, from 3-5 slices at prede ned locations 3 to whole organ coverage ( [11][12][13] ). Other derived quantities have been suggested such as histogram based measures 14 and texture-based scores were employed on T2weighted imaging [11][12][13] .…”

“…Most studies evaluate mean T2* over the entire organ with some variation in terms of coverage, from 3-5 slices at prede ned locations 3 to whole organ coverage ( [11][12][13] ). Other derived quantities have been suggested such as histogram based measures 14 and texture-based scores were employed on T2weighted imaging [11][12][13] . Visual assessment of the placenta, in particular, increased heterogeneity both over gestational age and in disease 15 has also been described as an additional measure to mean T2*.…”