Evaluation Of Brain Volumes Development Of Fetuses With Isolated Mild Ventriculomegaly Based On MRI

BackgroundIsolated mild ventriculomegaly(IMVM)is one of the common intracranial structural abnormalities observed prenatally.Previous studies have shown that the prognosis of fetuses with unilateral IMVM is slightly better than that of fetuses with bilateral IMVM.And there were no significant differences observed in the absolute brain volume of the brain hemisphere between the expanded and non-expanded hemispheres in fetuses with IMVM.However,there is currently limited research on the volumetric changes of various brain structures between the expanded and non-expanded hemispheres in fetuses with IMVM.Therefore,the developmental changes in brain volume of various brain regions in the expanded and non-expanded hemispheres of fetuses with IMVM remain unclear.ObjectiveTo investigate the developmental changes in brain volume of fetuses with IMVM based on MRI,and to explore the differences in brain volume development between the expanded and non-expanded hemispheres in fetuses with IMVM.MethodsA prospective study was conducted on 21 fetuses with IMVM at Guangzhou Women and Children’s Medical Center,with gestational ages ranging from 26W to 35W.Quantitative volume data of 30 brain regions,including the frontal lobe,parietal lobe,temporal lobe,occipital lobe,insula,gray and white matter of the cingulate gyrus,lateral ventricle,basal ganglia,and thalamus,were obtained by manually drawing the regions of interest(ROIs)of each brain region.The absolute volumes referred to the actual measured data of each brain region while the relative volumes referred to the ratio of the actual measured data of each brain region to the total volume of the supratentorial brain(the sum of all the absolute volumes of 30 brain regions).The absolute and relative volumes of each brain region of the expanded and non-expanded hemispheres were compared,and the correlations between the lateral ventricle and other brain regions of the expanded and non-expanded hemispheres in IMVM fetuses were analyzed.ResultsApart from the volume of the lateral ventricles,there were no statistically significant differences in absolute brain hemisphere volumes between the expanded and non-expanded hemispheres in fetuses with IMVM.The relative volumes of gray and white matter in the frontal lobe[9.36(8.68,10.4)vs.9.98(9.35,10.64)];(20.55±1.19 vs.21.3±1.36)and temporal lobe[6.80(6.39,7.08)vs.6.99(6.61,7.26)];(12.91 ±1.20 vs.13.62±0.90)of the expanded hemisphere were smaller than those in the nonexpanded hemisphere,with statistically significant differences(P<0.05).ConclusionsThe relative volumes of gray and white matter in the frontal and temporal lobes of IMVM fetuses were smaller in the expanded hemisphere than those in the non-expanded hemisphere,which might indicate that the frontal and temporal lobes of fetuses with IMVM may be more susceptible to the enlargement of the lateral ventricle.Furthermore,this could be a potential factor for adverse outcomes in fetuses with IMVM,and further large-scale studies would be needed to clarify the developmental patterns of the expanded and non-expanded hemispheres in fetuses with IMVM.BackgroundIsolated mild ventriculomegaly(IMVM)has an uncertain prognosis,and the outcomes can vary significantly among different IMVM fetuses.Some studies believe that IMVM may be a normal physiological variation that doesn’t affect the brain development of IMVM fetuses.However,current studies suggest that IMVM fetuses exhibit changes in the developmental relationship between the lateral ventricles and surrounding brain structures.Compared to normal fetuses,IMVM fetuses have increased absolute brain volume,mainly observed in the absolute volume of gray matter in the cingulate gyrus.However,there is still limited research on the specific changes in brain structure volume development of each brain structure in IMVM fetuses.The gestational age ranges are also narrowed in some studies.Therefore,the specific changes in brain structure volume in IMVM fetuses are still unclear and controversial.ObjectiveTo investigate the changes in brain structure volume development in IMVM fetuses based on MRI,and to explore the differences in brain structure development between IMVM fetuses and a control group(CG)of fetuses with normal MRI findings.MethodsA prospective study was conducted on 20 IMVM fetuses and 20 normal fetuses at Guangzhou Women and Children’s Medical Center,with a gestational age range of 26W35W.Quantitative volume data for each brain region were obtained by manually drawing 30 regions of interest(ROIs)in both cerebral hemispheres(frontal lobe,parietal lobe,temporal lobe,occipital lobe,insular cortex,gray and white matter of the cingulate gyrus,lateral ventricles,basal ganglia,and thalamus).The absolute volumes referred to the actual measured data of each brain region while the relative volumes referred to the ratio of the actual measured data of each brain region to the total volume of the supratentorial brain(the sum of the absolute volumes of 30 brain regions).The correlation between the lateral ventricles and other brain regions in the dilated side of the lateral ventricles of IMVM fetuses,the non-dilated side of the lateral ventricles of IMVM fetuses,and CG fetuses.The differences in brain volume development of different brain structures were also compared between the dilated and non-dilated sides of IMVM fetuses and CG fetuses.A two-tailed P-value<0.05 was considered statistically significant.ResultsIn the CG fetuses and the non-dilated side of IMVM fetuses,there was no statistical significance in the correlation between the absolute volume of the lateral ventricles and the absolute volume of other brain regions.The absolute volume of the dilated side of the lateral ventricles of IMVM fetuses was positively correlated with the absolute volume of other brain regions(P<0.05).In terms of total brain volume,the absolute volume of the supratentorial brain in the dilated side of IMVM fetuses was larger than that in CG fetuses(88.31 ± 29.36 vs.77.67 ± 25.80,P=0.001),while the absolute volume of the gray matter in the supratentorial area of the non-dilated side of IMVM fetuses was larger than that in CG fetuses(25.32 ± 7.02 vs.23.63 ± 6.35,P=0.031).In the comparisons of different brain regions,the absolute volumes of basal ganglia and occipital lobe gray matter in both dilated and non-dilated sides of IMVM fetuses were larger than those in CG fetuses.Additionally,the absolute volume of temporal lobe gray matter in the nondilated side of IMVM fetuses was larger than that in CG fetuses(5.81 ± 1.47 vs.5.32 ±1.36,P=0.031),while the absolute volume of occipital lobe white matter in the dilated side of IMVM fetuses was larger than that in CG fetuses[7.87(5.89,9.22)vs.7.18(5.38,8.42),P=0.017].However,in terms of relative volume,there were no statistically significant differences in the volume of each brain region between the non-dilated IMVM fetuses and CG fetuses(P>0.05).The relative volumes of gray and white matter in the frontal and parietal lobes and the white matter in the temporal lobe were significantly smaller in the dilated side of IMVM fetuses than those in CG fetuses.ConclusionsThere were differences in brain structure volume development between IMVM fetuses and CG fetuses,mainly in the dilated side of IMVM fetuses.The changes in brain structure volume might provide new evidences for the changes in brain volume in IMVM fetuses,which could be the basis for poor prognosis in IMVM fetuses.However,largesample,multi-center,and prospective studies combined with functional brain research need to be conducted to validate our findings.