Diffusion-T2 correlated spectroscopy imaging to explore possible placental composition changes over gestation.

BACKGROUND: Placenta plays a vital role for fetal growth and development during pregnancy. Currently, antenatal noninvasive imaging techniques to directly evaluate placental function remains challenge. Diffusion-T2 correlated spectroscopy imaging (DT2SI) can provide compositional information for different organs in-vivo. The aim of this study was to investigate the use of DT2SI as a tool to elucidate the placental composition change over gestation in healthy pregnancy. METHODS: Forty healthy singleton pregnancies were retrieved from our placental MRI research database. MRI was performed at 23.1-36.0 weeks of gestational age (GA) in a 3.0T system. DT2SI measurements were performed using DWI sequence with 7 b-values combining 4 TEs. ROIs were manually defined inside placenta on five cross-sectional slices covering the most central part of placenta. D-T2 Spectra were constructed and segmented into 9 compartments: A1(low D, short T2), A2(low D, medium T2), A3(low D, long T2), B1(medium D, short T2), B2(medium D, medium T2), B3(medium D, long T2), C1(high D, short T2), C2(high D, medium T2), C3(high D, long T2). Volume fraction Vm of each compartment m was obtained voxel by voxel, and general Vm of whole ROI was calculated for each participant. The relationships of Vm to GA were assessed by Pearson correlation. RESULTS: Four to five peaks could be observed in the spectrum for most subjects. Strong correlation between DT2SI Vm and GA was found. VA1 (r = 0.633, p < 0.001) showed a significant increase with GA. VA2 (r=-0.465, p = 0.002) and VA3 (r=-0.653, p < 0.001) showed a moderate/remarkable decrease. The compartment VB1 (r = 0.358, p = 0.023), VC1 (r = 0.411, p = 0.008) illustrate a slight/moderate increase. Other compartments have low concentration (average V < 3%). CONCLUSIONS: Comprehensive information on evolution of placenta composition with gestation could be provided by DT2SI, suggesting its unique value for assessing placental function during pregnancy.