• Ditte Nymark Hansen
5. Term (Master thesis), Medicine, Master (Master Programme)
Objective
The prediction of inter-twin birth weight discordance by different markers is presented in the literature with very low specificity and sensitivity. Fetal markers such as discordance in crown rump length, abdominal circumference and estimated fetal weight (EFW) are associated with, but poor predictors of, birth weight discordance. Therefore, new placental markers to predict inter-twin birth weight discordance are highly needed.
Recently, it has been suggested that placental diffusion is reduced in FGR singleton pregnancies, which makes it a potential marker for weight discordance in twin pregnancies.
The aim of this study was to investigate the association between inter-twin placental apparent diffusion coefficient (ADC) differences, estimated by diffusion weighted imaging (DWI), and inter-twin birth weight differences.
Methods
We retrospectively evaluated 1.5T placental magnetic resonance imaging (MRI) using the DWI sequence (10 b-values in range from 0-1000 sec/mm2) from 17 dichorionic twin pregnancies (gestational age 20+4 to 35+4 weeks). One pregnancy was excluded from the analysis because of contractions during the DWI sequence. Regions of interest were drawn in five slices in each placenta. ADC values (mean of 5 slices) were calculated as a linear regression analysis in each placenta, based on the signal intensity in the three highest b-values (200-1000 sec/mm2) of the MRI. Inter-twin placental ADC differences were calculated as the placental ADC value of the smaller twin subtracted from the placental ADC value of the larger twin, expressed as a percentage of the larger ADC value. Inter-twin birth weight differences were calculated as the birth weight of the smaller twin subtracted from the birth weight of the larger twin, expressed as a percentage of the larger birth weight.
The hypothesis that placental ADC was lower in the smaller twin when compared to the larger co-twin was tested using a paired t-test. The association between inter-twin placental ADC differences and the inter-twin birth weight differences was investigated using linear regression.
Results
The mean inter-twin placental ADC difference was -0.03±9.45 % (mean±SD). This difference was not significant, when tested using a paired t-test, p-value = 0.989. Consequently, no association could be demonstrated between the inter-twin placental ADC difference and the inter-twin birth weight difference.
Conclusion
Placental ADC is not a good marker of inter-twin birth weight difference.
LanguageMultiple languages
Publication date21 Dec 2015
Number of pages52
External collaboratorGynækologisk-Obstetrisk afdeling, Aalborg Universitetshospital Nord
Overlæge Anne Sørensen anns@rn.dk
Place of Internship
ID: 224392791