ABSTRACT
Objectives:To explore the value of blood oxygen level-dependent (BOLD) MRI in evaluating the changes of placental oxygenation during maternal hyperoxia.Methods:From October 2017 to March 2020, 22 singleton pregnant women with normal placenta showed by ultrasound were prospectively included in Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. Pregnant women wore oxygen mask before examination, and then underwent BOLD MRI examination for 10 min. The pregnant women inhaled air in the first 3 min and continuously inhaled oxygen with purity greater than 90% in the next 7 min (flow rate 12 L/min). The average value of BOLD signal of the whole placenta, fetal side of placenta, maternal side of placenta and maternal kidney were measured and calculated in the first 3 min as before oxygen and the last 3 min of the end of oxygen inhalation as after oxygen. The ΔBOLD was calculated which was the change value of BOLD signal before and after oxygen inhalation. The BOLD values of placenta and maternal kidney before and after oxygen inhalation were compared by using paired t-test. The ΔBOLD of the whole placenta, the fetal side of the placenta and the maternal side of the placenta were compared by using one-way ANOVA, and the LSD method was used for pairwise comparison between groups. Results:There were significant differences in BOLD values of the whole placenta, fetal side of placenta and maternal side of placenta before and after oxygen inhalation ( t=-4.62, P<0.001; t=-4.73, P<0.001; t=-3.57, P=0.002). There was no significant difference in BOLD value of maternal kidney before and after oxygen inhalation ( t=0.35, P=0.740). The ΔBOLD values of the whole placenta, fetal side of placenta and maternal side of placenta were (12.8±2.2)%, (15.1±2.7)% and (6.4±1.3)% respectively. The overall difference was statistically significant ( F=4.49, P=0.015). The results of pairwise comparison showed that there was no significant difference in ΔBOLD between the whole placenta and the fetal side of the placenta ( P=0.450). There were significant differences in ΔBOLD between whole placenta and maternal side of placenta ( P=0.037) and between fetal side and maternal side of placenta ( P=0.005). Conclusion:Under the condition of maternal hyperoxia, the BOLD signal of placenta increased significantly, and the change of fetal side of placenta was more obvious than that of maternal side. BOLD-MRI has the potential of semi-quantitative and real-time evaluation of placental oxygenation.
ABSTRACT
Objective To investigate the feasibility of ADC values in the evaluation of normal fetal brain development by measuring ADC values changes in specific regions with advancing gestational age.Methods Forty fetuses(gestational age:24 to 41 weeks) with normal brain underwent DWI(b value were 0 and 600 s/mm2).ADC values of the frontal white matter(WM),occipital WM,thalamus,basal ganglia,and cerebellum were measured by post-processing software.The differences among different regions' ADC values were calculated by repeated measurements of ANOVA,and simple linear regression was used to evaluate the relationship between ADC values and gestational age.Results The mean ADC valuesof 40 fetuses were(1 800±214) ×10-6mm2/s in frontal WM,(1 400±100) ×10-6mm2/s in basal ganglia,(1 300±126) ×10-6mm2/s in thalamus,(1 700±133) ×10-6mm2/s in occipital WM and(1 400± 155) × 10-6mm2/s in cerebellum,respectively.There was significant difference in the ADC values among the five regions(F=80.813,P＜0.01).In pair-wise comparison,ADC values of basal ganglia,thalamus and cerebellum had no significant difference; however,others had significant difference between each other.With the increasing gestational age,ADC values of basal ganglia,thalamus,occipital WM and cerebellum decreased,and had significant negative correlations with gestational age(Pearson correlation coefficient were-0.568,-0.716,-0.830 and-0.700,respectively,all P＜0.01).In terms of ADC value,occipital WM declined fastest with gestational age,followed by cerebellum and thalamus,and the slowest was basal ganglia.Frontal ADC values showed no correlation with gestational age(P＞0.05).Conclusions Specific regions of fetal brain have specific ADC values,and ADC values of the region undergo regular change with advancing gestational age.ADC value is a specific quantitative parameter that could help to evaluate normal brain development and early diagnosis of fetal brain lesions.
ABSTRACT
Objective To demonstrate the value of eombined application of prenatal ultrasonography with fetal magnetic resonance imaging(MRI) in the diagnosis of monochorionic muhifetal realformations. Methods Fourteen cases of muhifetal malformations,detected by prenatal ultrasonography,received MRI within 48 h afterwards.All diagnosis were confirmed after delivery or mid-term termination.All imaging results of the 14 cases were retrospectively reviewed. Results Among the 14 cases,there were 7 acardias,5 Conjoined twins and 2 demise of multifetuses.Comparing ultrasound with MRI,we found that:(1)In cases with acardia and demise of multifetusea,ultrasound could diagnose correctly and be an important tool for follow-up,while MRI could demonstrate organs and structures of the acardiac recipient more clearly and detect the secondary changes of brain in the donor and survived fetus.(2)In Conjoined twins,ultrasound was superior to MRI in demonstrating the structure and function of cardiovascular system : and equivalent to MRI in identifying stomach,kidney,bladder and limbs;but inferior to MRI in identifying esophagus,lung,liver and intestinal,especially in the brain. And MRI could demonstrate two fetuses and the relationship between them in COnjoined twins simultaneously. Conclusions Prenatal ultrasonography and MRI have their own advantages and disadvantages in diagnosing monochorionic multifetal malformations.But the combination of prenatal ultrasonography and fetal MRI may be more valuable.