Placental Flattening via Volumetric Parameterization

Abstract

We present a volumetric mesh-based algorithm for flattening the placenta to a canonical template to enable effective visualization of local anatomy and function. Monitoring placental function in vivo promises to support pregnancy assessment and to improve care outcomes. We aim to alleviate visualization and interpretation challenges presented by the shape of the placenta when it is attached to the curved uterine wall. To do so, we flatten the volumetric mesh that captures placental shape to resemble the well-studied ex vivo shape. We formulate our method as a map from the in vivo shape to a flattened template that minimizes the symmetric Dirichlet energy to control distortion throughout the volume. Local injectivity is enforced via constrained line search during gradient descent. We evaluate the proposed method on 28 placenta shapes extracted from MRI images in a clinical study of placental function. We achieve sub-voxel accuracy in mapping the boundary of the placenta to the template while successfully controlling distortion throughout the volume. We illustrate how the resulting mapping of the placenta enhances visualization of placental anatomy and function. Our implementation is freely available at https://github.com/mabulnaga/placenta-flattening.

Placental MRI: Development of an MRI compatible ex vivo system for whole placenta dual perfusion

“…As new therapies are investigated for diseases such as preeclampsia, MRI-based assessments of the placenta's vasoactive profile in vivo could prove crucial, and with improvement the platform we proposed here could be well suited to develop and validate these assessments [32,33,35]. Additionally, as we become more adept at our procedures, we hope to compare in vivo and ex vivo imaging of the same placenta with the help of software tools to coregister the images [44].…”

The use of functional placental magnetic resonance imaging for assessment of the placenta after prolonged preterm rupture of the membranes in vivo: A pilot study

“…Further advances in MRI acquisition and reconstruction strategies would enable the use of further high resolution three‐dimensional reconstruction techniques 33 and so facilitate this in the future. Efforts to display the placental tissues in an agreed coordinated system could further add to the specificity of the localization of lesions 34,35 …”

APPLAUSE: Automatic Prediction of PLAcental health via U-net Segmentation and statistical Evaluation

“…These include placental 3D reconstruction, i.e. using orthogonal slice stacks or multiple dynamics as has been recently proposed for T2* data of the brain ( Blazejewska et al., 2017 ) and the placenta ( Uus et al., 2020 ) or inter-slice motion correction techniques ( Luo et al., 2017 ) to improve the 3D continuity of the data thus enabling 3D patch-based segmentation and/or placental flattening techniques ( Abulnaga, Abaci Turk, Bessmeltsev, Grant, Solomon, Golland, 2019 , Miao, Mistelbauer, Karimov, Alansary, Davidson, Lloyd, Damodaram, Story, Hutter, Hajnal, Rutherford, Preim, Kainz, Groller, 2017 ), resulting in representations in a common coordinate system.…”