Improved fetal blood oxygenation and placental estimated measurements of diffusion-weighted MRI using data-driven Bayesian modeling.

Dimitra Flouri,Nada Mufti,Giles Kendall,Andrew Melbourne,Rosalind Aughwane,Magdalena Sokolska,David Atkinson,Sebastien Ourselin,Kasia Maksym,Alan Bainbridge,Anna L David,David Owen,Tom Vercauteren

doi:10.1002/mrm.28075

Abstract

PurposeMotion correction in placental DW‐MRI is challenging due to maternal breathing motion, maternal movements, and rapid intensity changes. Parameter estimates are usually obtained using least‐squares methods for voxel‐wise fitting; however, they typically give noisy estimates due to low signal‐to‐noise ratio. We introduce a model‐driven registration (MDR) technique which incorporates a placenta‐specific signal model into the registration process, and we present a Bayesian approach for Diffusion‐rElaxation Combined Imaging for Detailed placental Evaluation model to obtain individual and population trends in estimated parameters.MethodsMDR exploits the fact that a placenta signal model is available and thus we incorporate it into the registration to generate a series of target images. The proposed registration method is compared to a pre‐existing method used for DCE‐MRI data making use of principal components analysis. The Bayesian shrinkage prior (BSP) method has no user‐defined parameters and therefore measures of parameter variation in a region of interest are determined by the data alone. The MDR method and the Bayesian approach were evaluated on 10 control 4D DW‐MRI singleton placental data.ResultsMDR method improves the alignment of placenta data compared to the pre‐existing method. It also shows a further reduction of the residual error between the data and the fit. BSP approach showed higher precision leading to more clearly apparent spatial features in the parameter maps. Placental fetal oxygen saturation (FO2) showed a negative linear correlation with gestational age.ConclusionsThe proposed pipeline provides a robust framework for registering DW‐MRI data and analyzing longitudinal changes of placental function.

Highlights

Quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) parameters have been increasingly used to characterize abnormal placental microstructure.[1,2,3,4] Monitoring placental function using MRI may improve the understanding and diagnosis of placental insufficiency, which is a significant cause of perinatal morbidity and loss
We have described a framework for motion correction and parametric model fitting applied to quantitative placenta imaging data
model-driven registration (MDR) performance was compared to principal component registration (PPCR).[12]

Summary

Introduction

Quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) parameters have been increasingly used to characterize abnormal placental microstructure.[1,2,3,4] Monitoring placental function using MRI may improve the understanding and diagnosis of placental insufficiency, which is a significant cause of perinatal morbidity and loss. DW-MRI is becoming a powerful tool to obtain placenta perfusionrelated measures without the administration of a contrast agent.[5,6] DW-MRI in combination with the intra-voxel incoherent motion (IVIM) model provides a non-invasive technique to assess tissue properties related to perfusion and flow Another method for assessing placental function is T2 relaxometry which provides information on the static tissue composition and intrinsic tissue T2 value.[7,8] A recent study has proposed a joint placental model and acquisition, named Diffusion-rElaxation Combined Imaging for Detailed placental Evaluation (DECIDE).[6] The DECIDE model is a three-compartment model of placental perfusion that combines T2 relaxometry and DW imaging

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Conclusion