*4.1.3. Phase-contrast X-ray computed tomography*

X-rays are electromagnetic waves with characteristic amplitude and phase. When X-rays penetrate a sample, its amplitude decreases and the phase gets shifted. Conventional X-ray imaging (radiography) is based on absorption contrast (i.e. amplitude imaging) and represented by the internal mass density distribution within the sample (**Figure 6A** and **B**). Unfortunately, only sensitivity to X-ray distribution is not enough for a detailed analysis of the samples containing biological soft tissues such as embryos, unless it is either combined with contrast agents or performed at higher X-ray doses. Another way of solving this issue is by exploiting the phase information of X-rays. Since lighter elements, such as hydrogen, carbon, nitrogen, and oxygen are 1000 times more sensitive to phase-shift compared to the actual absorption [56], they can be used to detect the phase-shift. To that end, it is essential to convert the phase shift into a change in X-ray intensity, which can be measured easily by current-detecting devices. Conversion methods, such as interferometry and diffractometry, are applied for the

**Figure 5.** The results of MRI from several imaging devices. A, B: 2.34 T super parallel MRM (MR microscope), developed by Prof. Kose et al. in the University of Tsukuba. C, D: Pre-clinical MRI (Bruker BioSpin, 7 T) in the Human Health Sciences, Kyoto University Graduate School of Medicine, Japan. E, F: Clinical MRI (Siemens Magnetom, 3 T) in the Kyoto University Hospital, Japan.

2D/3D images of the samples in combination with CT. An embryo or an early fetus, mostly

Congenital Anomalies in Human Embryos http://dx.doi.org/10.5772/intechopen.72628 35

Ultrasonography of living embryos and fetuses is very commonly performed nowadays, and many malformations can be diagnosed during the early prenatal period. In the cases of pregnancy termination, not all the aborted fetuses are dissected and pathologically diagnosed, due to technical difficulties associated with the dissection of small fetuses. However, the imaging modalities presented here can be used for autopsy imaging of embryos and fetuses, regardless of their size. If any clue to the fetal anomaly (that might have led to the abortion) could be identified by using these imaging modalities, supplemented by appropriate genetic tests, then a final accurate diagnosis can be obtained. Based on the final diagnosis, parents would be provided with sufficient detailing of their lost pregnancy, which would enable them to

The imaging modalities described in this section are summarized in **Figures 5** and **6**. The appropriate modalities for imaging dead embryos or fetuses should be used depending on

Amniotic fluid, chorionic villi, and umbilical cord blood are used for genetic analyses of human embryos and fetuses. Recently, a new approach for prenatal testing was proposed in the name of noninvasive prenatal testing (NIPT) that uses DNA fragments derived from maternal villus cells to determine the genetic information of the fetus. In comparison to maternal serum analysis, NIPT has considerably higher sensitivity and specificity for aneuploidy [65]. However, due to the infrequent derivation of cell-free DNA (cfDNA) from multiple sources such as in placental mosaicism, maternal conditions including cancer, or fetal and/or maternal copy number variation (CNV) [66], NIPT has a risk of predicting false-positive and false-negative results.

The cell samples obtained from amniotic fluid and chorionic villi may be used for both screening and diagnostic tests. Traditional karyotype analysis is the most commonly used method to examine cells, obtained from chorionic villus sampling (CVS) and amniocentesis (AC), for the diagnosis of aneuploidies and large rearrangements. The diagnostic accuracy of traditional karyotype analysis is higher than 99% for aneuploidy and for chromosomal abnormalities larger than 5–10 Mb [67]. On the other hand, fluorescence in-situ hybridization (FISH) analysis can detect specific chromosomes or chromosomal regions by using fluorescently labeled probes. The turnaround for FISH results (usually within 2 days) is faster than that of conventional karyotyping results (7–14 days, including the cell culture period). Due to the existence of false-positive and false-negative reports, FISH [68–70] is considered as a mere screening test, although still commonly used to screen chromosomes 13, 18, 21, X, and Y. Therefore, clinical diagnosis using FISH results should be supplemented by other clinical and laboratory analyses such as abnormal ultrasonography, positive screening test using maternal serum and/or soft markers, confirmatory traditional metaphase chromosome analysis, or chromosomal microarray analysis (CMA). CMA is capable of detecting small chromosomal aneuploidies that cannot otherwise be identified by conventional karyotyping [71]. Since CMA can be performed without cell or tissue culture, the results can be obtained within 3–7 days. Since CMA can also be carried out with

composed of soft tissue, is suitable for pCT imaging (**Figure 6C** and **D**).

receive a genetic counseling prior to the next pregnancy.

*4.2.2. Genetic analysis of the human embryo and fetus*

the stage of pregnancy.

**Figure 6.** The results of X-ray CT. A, B: Clinical CT (Toshiba Alexion) in the Laboratory of Physical Anthropology, Graduate School of Science, Kyoto University, Japan. C, D: Phase contrast CT, Photon Factory of the KEK (High Energy Accelerator Research Organization) in Tsukuba, Japan. A, C: Surface reconstruction and B, D: midsagittal section.

generation of 2D and 3D images using synchrotron radiations from appropriate devices [57, 58]. An image of a human embryo at CS 17, obtained by applying a two-crystal X-ray interferometer [59], is displayed in **Figure 6C** and **D**.
