Purpose: To investigate the potential of bi-exponential model of diffusion-weighted (DW) signal decay to quantify diffusion and perfusion changes in human placenta of normal pregnancies due to its development.
Methods: 26 normal pregnancies at 19-37 weeks of gestation underwent Magnetic Resonance Imaging (MRI) examination at 1.5 T. DW Spin-Echo Echo Planar Imaging with diffusion gradients applied along 3 no-coplanar directions at seven different b-values (0,50,100,150,400,700,1000 s/mm2) was used. Apparent diffusion coefficient (ADC), pseudodiffusion (D*) and perfusion fraction (f) were extracted in selected placenta regions: umbilical (U-ROI), central (C-ROI) and peripheral (P-ROI). The relation between ADC, D*, f and mother age, gestational age (GA), Body-Mass Index (BMI), basal Glycaemia (bG), were evaluated. Pearson correlation with Bonferroni correction was used.
Results: A significant negative correlation was found between ADC and GA, for GA≥30w in P-ROI, while no-dependence of ADC on GA was observed in GA range 19-29 weeks. A positive linear correlation was found between f and GA in the C-ROI and between f and GA in P-ROI for GA≥30 week. No significant correlations were found between ADC, D*, f and age, BMI, bG.
Conclusion: ADC measurements in P-ROI of normal placenta reflects tissue changes occurring in the third trimester of gestation. Specifically, ADC decreases with GA increase. Besides, f increases with the GA increase in the C-ROI and during the third trimester of pregnancy in the P-ROI. These results suggest the potential of diffusion and perfusion parameters extracted by using a biexponential model to provide information about placenta changes during its development.
Keywords: ADC; DWI; Magnetic Resonance Imaging; Normal placenta; Perfusion.
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