Placenta microstructure and microcirculation imaging with diffusion MRI.

Area of Science:

• Medical Imaging
• Biophysics
• Neuroimaging

Background:

• Diffusion-weighted MRI (DW-MRI) is crucial for assessing tissue microstructure.
• Understanding placental microstructure is vital for monitoring fetal development and identifying pathologies.
• Existing microstructural models may not fully capture the complexity of placental tissue.

Purpose of the Study:

• To evaluate and compare various microstructural models for explaining DW-MRI signals in the human placenta.
• To determine the most effective biophysical model for placental imaging.

Main Methods:

• Scanned placentas from nine healthy pregnant subjects using a 3T scanner with a multishell, multidirectional diffusion protocol.
• Fitted multiple multicompartment biophysical models to the diffusion MRI data.
• Ranked model performance using the Bayesian information criterion.

Main Results:

• Anisotropic extensions of the intravoxel incoherent motion (IVIM) model consistently yielded the lowest Bayesian information criterion values.
• These anisotropic IVIM models, accounting for coherent orientation in microvascular and tissue microstructure, outperformed other models.
• Generated model parameter maps aligned with placental physiology.

Conclusions:

• Anisotropic IVIM models provide a superior explanation of placental diffusion MRI signals compared to standard diffusion tensor imaging (DTI) and conventional IVIM models.
• Future research will explore the sensitivity of these model-derived parameters to placental pathologies like fetal growth restriction and pre-eclampsia.