| ObjectiveUsing MRI balanced fast field echo (B-FFE) to evaluate the development of normal fetal brain and the size of ventricular system, to set up the reference value of normal fetal ventricle system between the different gestational age, to discuss the influence of gestational age, and to study the application of both MR and US in diagnosis of the fetus ventricle system abnormities.Materials and methods1. study population1)From March 2005 to March 2010, ninety-eight singleton pregnancy women whose fetus with CNS normities but other systems abnormities were investigated in US, and require further MRI examination. The age ranged from 21 to 45 years old, average (28.6±3.3) years old, The gestational weeks ranged from 24+0 to 40+6 weeks, average 31.5±5 weeks. Gestational age was determined on the basis of the last menstrual period and was confirmed by at least one previous sonographic examination performed during the first trimester.Normal cranial and fetal growth was obtained by measuring the biparietal diameter, head circumference, transverse cerebellar diameter, abdominal circumference and femur length.2) Ninety-eight singleton pregnancy women divided into 4 groups according to the embryo age and the research:group 1,24+0weeks-27 +6weeks,18 cases; group 2,28+0weeks～31+6 weeks,29 cases; group 3,32+0 weeks～35+6 weeks,30 cases; group 4,36-0 weeks～40+6 weeks, 21 cases. 3)From March 2005 to March 2010, forty-five singleton pregnancy women with US diagnosis of ventricle system abnormalities require further MRI examination. The age ranged from 23 to 39 years old? average (28.2±2.8) yeas old. The gestational weeks ranged from 27 to 40 weeks, averag 32.8±4.5 weeks. Both of them are healthy and their periods is regular. All MRI examination were carried out within 1 week after the ultrasound examination, before the examination, all of them were aware of the sensitivity, accuracy and limitations, and signed informed consent.2. Methods1)Fetus US was performed. The lateral cerebral ventricle plane, the thalamus plane and the cerebellum plane scanning were studied.2)MR1 was performed. The sequences included a multiplanar balanced fast field echo (B-FFE). The total examination time was approximately 30 minutes.3.observe index1) 98 cases of MRI B-FFE imaging, according to the changes of signals and morphological to assess the boundary of gray matter, the maturity of brain.2) The ventricle system was measured on MR in ningty-eight fetus, including the body and the triangle area of lateral ventricle, third ventricle, fourth ventricle.3) The results of the fouty-five fetus with ventricle abnormalities or suspected abnormities by US were campared with MRI. 4. Statistics analysisStatistical analysis was performed using the pearson correlation analysis method and SPSS 16.0 package for Windows. The results of them presented as mean±standard deviation. p<0.05 was considered statistically significant, p<0.01 was considered statistically very significant.Results1) Ninety-eight singleton pregnancy women whose fetus were conflmed or suspected of CNS abnormities by prenatal US accepted MR imaging. Ninety-three cases got satisfactory images. MR imaging was precluded because of claustrophobia(2 cases)and overfrequencyof fetal movement(3 cases).2) Ninety-three cases of MRI B-FFE imaging, the changes of fetal brain signals and morphological:24-26 or to 28 weeks of gestation, fetal brain was smooth, Parietooccipital sulcus, central sulcus and lateral fissure can be seen. The brain signal in real terms divided into three layers, cerebellar hemisphere divided into two levels signal. After 28 weeks the low signal levels around the brain ventricles disappeared.25 weeks later, cerebellar vermis appears.28-30 weeks of gestation, occipital and central regions of the brain groove back more obvious, gyri of occipital and parietal can be seen.30-33 weeks of gestation, gyrus of frontal and volume discount on cerebellar surface can be seen.36 weeks of gestation, the cerebral cortex folding is more extensive, closer and complete.3) Ninety-three cases of ventricle system measure1,lateral ventricle of the total group mean 5.92±0.69mm, showed close positive correlation with gestational age (r=0.772 P<0.01).2,The triangle area of lateral ventricle total group mean 6.59±0.84mm, showed close positive correlation with gestational age (r=0.777, P<0.01)。3n In second trimester, third ventricle difficult to observe, third trimester, the maximum value is 2mm。4,The anteroposterior diameter of the fourth ventricle of the total group mean 4.05±0.80mm, showed close positive correlation with gestational age (r=0.853, P<0.01)。5,Fourth ventricle transverse diameter of the total group mean 4.82±0.98mm, showed close positive correlation with gestational age (r=0.809, P<0.01)。4) The results of the Fouty-five fetus with ventricle abnormalities or suspected abnormities by US were campared with MRI. In 30(66.66%, 30/45)of 45 cases with confirmed or suspected of ventricle abnormalities by US, the diagnoses established by US and MR imaging were correct when compared with postnatal diagnosis:MR imaging provided more information than did US in 11 (24.44%,11/45)cases. MR corrected the US diagnosis in 3 (6.66%,3/45) cases, One (2.22 %,1/45)case provided more abnormal information on US and MR could not show.Conclusions1) MR B-FFE can clearly showed the process of fetal brain development and morphological changes, have more clinical value to evaluate the development of fetal brain。2) The body of a normal fetal lateral ventricle mean 5.92±0.69mm, the triangle area of lateral ventricle mean 6.59±0.84mm.Three ventricles are difficult to observe in the second trimester, third trimester, the maximum value is 2mm.The anteroposterior diameter of the fourth ventricle of the totalgroup mean 4.05±0.80mm.Fourth ventricle transverse diameter of the total group mean 4.82±0.98mm.The size of both lateral ventricles and fourth ventricle showed close positive correlation with gestational age.3) Gyrus, ventricular system morphology, midline structures such as the corpus callosum, septum pellucidum cavity as well as the posterior fossa strures, MRI compared with ultrasound has a greater diagnostic value, it is an important complement methods. |
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