Establishing and Comparing the Normal apparent Diffusion Coefficient Values of Fetal Organs and Placenta Using 1.5 Tesla and 3.0 T MRI at Various Gestational Age.

Background: Diffusion-weighted imaging (DWI) is the random Brownian motion of water molecules within a tissue voxel. The apparent diffusion coefficient (ADC) is a quantitative parameter calculated from the DWI that directly reflects the mobility of water molecules in biological tissues. The objective of this study was to establish and compare the normal reference ADC values of fetal organs and the placenta using 1.5 T and 3.0 T MRI at various gestational ages. Methods: This was a retrospective and prospective observational study. This study included one hundred and three (103) singleton pregnancies for each magnetic field strength. Diffusion-weighted imaging was performed using single-shot spin-echo-planar imaging (EPI) in the axial plane of the fetal head-trunk with a slice thickness of 4mm and diffusion gradient values of b = 0 and b = 700-800 s/mm2. Results: The mean ADC values of cerebral WM areas were significantly higher than the deep grey areas in the brain. The white-matter regions, lung, and placenta showed a positive and significant correlation with increasing gestational age in both field strengths. A statistically weak negative correlation was observed between increasing gestational age and ADC measurements obtained in the thalamus, cerebellum, pons, and kidney. Conclusion: This study gives the reference values for both 1.5T and 3T MRI of vital organs. The current study shows that diffusion-weighted MRI can offer a promising technique to evaluate the structural development of fetal organs and can potentially act as a biomarker for predicting the functionality of the fetal organs in abnormalities.

Single Nucleotide Polymorphism-Based Noninvasive Prenatal Testing: Experience in India.

INTRODUCTION: Noninvasive prenatal testing (NIPT) has revolutionized prenatal screening for chromosomal aneuploidies in some countries. Its implementation has been sporadic in developing countries. Given the genetic variation of the people in different countries, we evaluated the performance of the SNP-based NIPT in India . MATERIALS AND METHODS: The Panorama™ NIPT was performed in 516 pregnancies, which had tested intermediate-to-high risk on conventional first and second trimester screening. Results were confirmed either by invasive diagnostic testing or by clinical evaluation after birth. RESULTS: Of 511 samples analyzed, results were obtained in 499 (97.7%). Of these, 480 (98.2%) were low risk and 19 were high risk. A sensitivity of 100% was obtained for detection of trisomies 21, 18, 13 and sex chromosomal abnormalities. The specificity ranged from 99.3 to 100% for abnormalities tested. Taken together, the positive predictive value for trisomies 21, 18, 13 and monosomy X was 85.7%. The average fetal fraction was 8.2%, which is lower than the average observed elsewhere. CONCLUSION: This is the first report of detailed experience with NIPT in India and demonstrates comparable performance in all aspects of testing to the results elsewhere.

A retrospective exploratory study of fetal genetic invasive procedures at a University Hospital.

This is a retrospective analysis of the patient demographics and cytogenetic results of patients who underwent prenatal invasive testing for genetic analysis at the Foetal Medicine Division of the Department of Obstetrics and Gynecology, Sri Ramachandra Medical College and Research Institute. The main objective of this study was to characterise the changing trends in indications of pregnant women for foetal karyotyping in a 7-year period. A total of 257 procedures were performed in this period, and there was a significant change in the trend of indications for invasive prenatal diagnosis from an advanced maternal age in 2009 to a positive screen test by 2014. Chromosome abnormalities were observed in 9.8% of the cases, with trisomy 21 being the most frequent finding. The findings demonstrate the changing trends in screening and diagnostic testing in the tertiary care centre, with an acceptance of the first and second trimester maternal serum screening tests as a determinant for high-risk pregnancies. Impact statement What is already known on this subject? Despite the fact that India has one of the world's highest birth rates, there is still no public health care policy for the application of cytogenetic prenatal diagnosis. Nevertheless, we have been offering this test in our university teaching hospital since 2008, allowing us to characterise the changing trends in indications of pregnant women who sought invasive diagnostic procedures for foetal genetic studies. What do the results of this study add? The results of our study show that there were major changes in the common indications for prenatal diagnosis during the study period. In 2009, the main indication was an advanced maternal age, referred to in 31% of the cases, which declined steadily to 5% by 2014. In 2014, 51% of cases opted for a prenatal diagnosis because of a first trimester screen positive result, increasing from 12% in 2009. What are the implications of these findings for clinical practice and/or further research? This data is relevant as it would encourage other tertiary hospitals in developing countries like India to consider extending first trimester screening for all women, regardless of age and educate them on the options of prenatal genetic diagnosis for reassurance.