Quantitative ultrasound-based characterization of placental microstructure during preeclampsia

Preeclampsia is a life-threatening pregnancy disorder resulting from improper development of the placenta. B-mode ultrasound imaging is the ubiquitous tool for pregnancy imaging but does not provide enough contrast to detect changes in placenta microstructure during preeclampsia. Quantitative ultrasound (QUS) methods have been used to assess tissue microstructure in various organs, including the placenta. Our goal was to demonstrate how QUS parameter maps of the placenta correlate with biological features in the placenta’s microstructure. Ultrasound image data of 9 pregnant Sprague-Dawley rats were collected on gestational day 18 using the Vevo 2100 equipped with the LZ250 transducer (21 MHz center frequency). QUS parameter maps of 4–6 placentas per rat were generated using radiofrequency (RF) data from ultrasound image acquisitions. For each placenta, we generated 9 parameter maps: 5 using backscatter coefficient methods and 4 using envelope statistics. After imaging, placenta tissue samples were embedded in paraffin, sectioned, stained with hematoxylin and eosin (H&E), and scanned at 20x magnification using the Zeiss Slide Scanner. Backscatter coefficient parameters exhibited a linear correlation with cell nucleus diameter across the different regions of the placenta (R2 = 0.58 and p = 3.8e-6). Future studies will focus on studying preeclampsia with QUS in human placentas.