【作者】 张亚林；

【导师】 周启昌；

【作者基本信息】 中南大学 ， 影像医学与核医学， 2010， 博士

【摘要】 目的应用核磁共振成像(Magnetic resonance imaging, MRI)平衡式快速梯度回波(balanced fast field echo, B-FFE)序列评价正常胎儿脑发育及脑室系统大小,建立24孕周至40孕周间不同孕龄段正常胎儿脑室系统大小的参考值,评价胎龄对正常胎儿脑室大小的影响,探讨联合应用超声(Ultrasonography, US)与MRI对胎儿脑室扩张病因的诊断价值。对象与方法研究对象1)2005年3月-2010年3月,98例US提示胎儿神经系统无异常,伴有其他系统异常需要进行MRI检查的单胎妊娠孕妇,年龄21-45岁,平均(28.6±3.3)岁,胎龄24+0-40+6孕周,平均31.5±5周。既往体健,月经规律,孕周以末次月经时间计算,US检查胎儿双顶径、头围、腹围、股骨长度均符合相应孕周。2)98例孕妇根据胎龄分成4组：1组,24+0周-27+6周,18例；2组,28+0周-31+6周,29例；3组,32+0周-35+6周,30例；4组,36+0周-40+6周,21例。3)2005年3月-2010年3月,45例因US诊断脑室异常需要进一步进行MRI检查的单胎妊娠孕妇,年龄23-39岁,平均(28.2±2.8)岁,胎龄27+5-40+1孕周,平均32.8±45周。既往体健、月经规律,无妊娠合并症。所有胎儿均在US检查后1周内进行MRI检查,行MRI检查前孕妇均知晓该检查的敏感性、准确度及局限性,并签署知情同意书。2.扫描方法(1)US扫描方法：嘱孕妇仰卧位,经腹横切扫查,常规扫查侧脑室平面、丘脑平面、小脑平面。(2)MRI扫描方法：嘱孕妇平静均匀呼吸,仰卧位,取足先进方式。常规定位后,以胎头为中心,分别进行冠状位、横断位、矢状位T2WI(B-FFE序列)扫描。完成所有序列扫描时间约需时30min.3.观察指标(1)对98例行MRI B-FFE技术成像胎儿,根据MRI脑实质信号及形态变化评估脑灰白质的分界情况、脑回的成熟度。(2)对98例行MRI B-FFE技术成像胎儿进行脑室系统大小测量,包括侧脑室体部及三角区、三脑室、四脑室。(3)对45例US提示脑室系统异常或可疑异常的结果与MRI检查结果相对照,记录US与MRI诊断结果的符合情况。4.统计学分析所有数据均用SPSS16.0统计软件包录入和处理。测量结果以平均值±标准差(X士s)的形式描述,用Pearson相关分析法进行变量间的相关性分析。P<0.05为差异有显著性意义,P<0.01为差异有极显著性意义。结果1、98例孕妇接受MRI检查,93例成像顺利,2例因幽闭恐惧症、3例因胎动过频中断检查。2、93例胎儿MRI B-FFE成像脑信号及形态变化：24-26或28孕周,胎儿大脑表面基本光滑,顶枕沟、中央沟及外侧裂可见,大脑实质分三层信号,小脑半球分两层信号,28周后大脑脑室周围低信号层消失。25周小脑蚓部出现。28-30孕周,枕叶和中央回区域脑沟比较明显。30-33孕周后,额叶可见脑回,小脑表面可见卷折。36孕周,大脑皮层折叠较广泛,紧密而完整。3、93例胎儿脑室系统大小MRI测量：(1)侧脑室体部总群体均值为5.92±0.69mm,与孕周呈密切正相关(r=0.772,P<0.01)。(2)侧脑室三角区总群体均值为6.59±0.84mm,与孕周呈密切正相关(r=0.777,P<0.01)(3)三脑室测量结果显示：孕中期,三脑室难以观察到,孕晚期三脑室最大值为2mm。(4)四脑室前后径总群体均值为4.05±0.80mm,与孕周呈密切正相关(r=0.853,P<0.01)。(5)四脑室横径总群体均值为4.82±0.98mm,与孕周呈密切正相关(r=0.809,P<0.01)。4、45例US提示胎儿脑室系统异常或可疑异常的结果与MRI检查结果相对照,MRI与US诊断完全符合的病例30例占66.66%(30/45)；MRI补充US诊断11例占24.44%(11/45)；MRI更正US诊断3例,占全部病例的6.66%(3/45)；1例US提示异常而MRI未显示,占全部病例的2.22%(1/45)。结论1)磁共振B-FFE成像技术可清楚显示胎儿脑发育过程中信号及形态的变化,对于评价胎脑发育具有一定的临床价值。2)正常胎儿侧脑室体部均值为5.92±0.69mm,侧脑室三角区均值为6.59±0.84mm。胎儿三脑室孕中期均难以观察到,晚期横径小于2mm。四脑室前后径均值为4.05±0.80mm,宽度均值为4.82±0.98mm。MRI测量所得孕中晚期胎儿侧脑室及四脑室大小均与孕周呈密切正相关。3)胎儿脑沟回、脑室系统形态、脑中线结构如胼胝体、透明隔腔以及后颅窝等结构,MRI较US具有更大的诊断价值,是US检查的重要补充技术。更多还原

【Abstract】 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.更多还原