Abstract
The placenta mediates oxygen exchange between mother and fetus. MRI T2* relaxometry provides a non-invasive, in vivo measure of placental oxygenation. The response of placental T2* to a controlled change in maternal oxygenation has been studied in human pregnancy under hyperoxia, but the converse experiment under maternal hypoxia can not be performed for ethical reasons, motivating a nonhuman primate model. Placental oxygenation is spatially heterogeneous, so the effect of hypoxia need not be uniform across the T2* distribution. Fourteen pregnant rhesus macaques were imaged across 106–155 days of gestation, nine at a single gestational age, four at two, and one at three. This gave 20 within-subject comparisons of a normoxia baseline against maternal hypoxia. Each was made with a shift function: the difference in T2* between the two conditions at each of the nine deciles. Uncertainty was quantified with a spatial block bootstrap that preserves dependence between neighbouring voxels, and the intervals were controlled jointly across deciles with a studentised sup-t band. Placental T2* was lower under hypoxia across most of the distribution (166 of 180 decile differences, 92.2%; 150 of them significant), with the mean shift rising from 2.9ms (first decile) to 32.5ms (ninth). The shift function decreased with gestational age (Pearson (r) about to , significant at the 5% level at every decile). Because the conditions are compared through their distributions rather than voxelwise, the framework requires no registration between acquisitions and can be applied to other imaging-derived distributions.
Links to Paper and Supplementary Materials
Main Paper (Open Access Version): https://papers.miccai.org/miccai-2026-sat/paper/PIPPI_019.pdf
SharedIt Link: Not yet available
SpringerLink (DOI): Not yet available
Supplementary Material: Not Submitted
Link to Open Review
BibTex
@InProceedings{FajDie_Shift_MICCAISAT2026,
author = { Fajardo-Rojas, Diego AND Schabel, Matthias AND Brudkiewicz, Katharine AND Xiao, Zhennan AND Kroenke, Christopher D. AND Roberts, Victoria H. J. AND Melbourne, Andrew},
title = { { Shift functions with a spatial block bootstrap for within-subject comparison of placental T2* distributions under maternal hypoxia in a nonhuman primate model } },
booktitle = {Medical Image Computing and Computer Assisted Intervention -- MICCAI 2026 Workshops and Challenges},
year = {2026},
publisher = {Springer Nature Switzerland},
volume = {LNCS 17257},
month = {pending},
page = {pending}
}