Miao et al. describe an in utero procedure for generating placenta maps. Typically, the placenta is evaluated ex vivo by placing it on a flat table and assessing its structure.

The placenta is a 3D organ that is typically compressed while inside the mother’s uterus. Due to the lack of space in the mother’s womb and fetal movements, the placenta is deformed in utero and appears much differently from the ex vivo placenta. The authors are developing this procedure for examining the placenta in utero so that clinical examinations and large population studies can be conducted.

Pathologies that could receive better diagnostics and treatment from this standardized procedure include twin-to-twin transfusion syndrome (TTTS), preeclampsia, preterm birth, and stillbirth.

In utero examination of the placenta is done by magnetic resonance imaging (MRI). Since this is a noninvasive method that does not use ionizing radiation, an MRI scan of the fetus can be done as early as 12 weeks or at the end of the first trimester.

Obtaining good imaging that can be compared across different placentas is a difficult task. In utero, the placenta is constantly moving due to the fetal and bowel motion and the mother’s respiration. Respiration motion is predictable and can be corrected. The other motions require oversampling of the input space, slice-to-volume registration, and super-resolution techniques.

In summary, the authors have developed a procedure for studying a placenta in utero by acquiring enough information for a 3D image of the placenta and then going through four steps: 1) segmentation, which generates the mask for the placenta; 2) slicing, which creates layers of the placenta structure; 3) splitting, which separates the layers into a fetal and maternal side and then flattens the output into two dimensions; and 4) visual mapping, which creates a standardized view of the isolated placenta.

The visual map is similar to a geographic map where an image of a 3D sphere is reduced to two dimensions (with some distortion) and parts of the map can be studied using a latitude and longitude coordinate system.

The authors presented their procedure for assessing placental structures to clinical staff consisting of pediatricians and radiologists. A Likert-style survey was given and the survey was divided into assessing the instructions given for using their procedure and assessing the acceptance of the authors’ procedure by clinical staff. Radiologists, who are familiar with studying MRI output, gave higher acceptance scores than pediatricians, who are not as familiar with interpreting this type of imaging.

This paper is a good example of developing a standardized procedure for studying a part of the human body within a clinical environment and assessing the effectiveness of the procedure by surveying the clinical staff who use this procedure.