Verification of fetal brain responses by coregistration of fetal ultrasound and fetal magnetoencephalography data

Fetal magnetoencephalography (fMEG) is used to study neurological functions of the developing fetus by measuring magnetic signals generated by electrical sources within the fetal brain. For this aim either auditory or visual stimuli are presented and evoked brain activity or spontaneous activity is measured at the sensor level. However a limiting factor of this approach is the low signal to noise ratio (SNR) of recorded signals. To overcome this limitation, advanced signal processing techniques such as spatial filters (e.g., beamformer) can be used to increase SNR. One crucial aspect of this technique is the forward model and, in general, a simple spherical head model is used. This head model is an integral part of a model search approach to analyze the data due to the lack of exact knowledge about the location of the fetal head. In the present report we overcome this limitation by a coregistration of volumetric ultrasound images with fMEG data. In a first step we validated the ultrasound to fMEG coregistration with a phantom and were able to show that the coregistration error is below 2 cm. In the second step we compared the results gained by the model search approach to the exact location of the fetal head determined on pregnant mothers by ultrasound. The results of this study clearly show that the results of the model search approach are in accordance with the location of the fetal head.     

Influence of fetal growth patterns on sonographic estimation of fetal weight

Six published fetal weight estimating regression models proposed for clinical use were evaluated in 259 pregnant women who delivered within 72 h of an ultrasound evaluation performed with sector scanner. The patient sample included 89 (33.2%) fetal weights that were below the 10th or above the 90th percentile for menstrual age. The actual mean percent error (systematic error), standard deviation (random error), and the number of large errors of prediction for all equations were greatest in fetuses that were small- and large-for-gestational age. Whereas there were no significant differences between equations for the patient sample as a whole, equation AC,BPD (Shepard) had the smallest systematic error in intrauterine growth retarded, premature, and normal-term fetuses less than 4000 g. Conversely, the systematic error of the models that included femur length was smallest at the upper end of the weight scale and in macrosomic fetuses in general. In that regard, the accuracy of fetal weight prediction could be increased by selecting the appropriate model for the proper clinical indications. Although these findings can be explained by the limitations of the current regression models in estimating fetal soft tissue mass, a subtle effect of the use of the sector scanner on the results of this study cannot be completely excluded and requires further investigation.     

Evaluation of fetal tissue viscoelastic characteristics for robotic fetal surgery

Purpose  

Minimally invasive fetal surgery is expected to improve therapeutic outcomes, and surgical robots are expected to aid the dexterous manipulation of fragile fetal tissues. Although robots are currently used for surgery on soft tissues, practical information concerning the viscoelastic characteristics of fetal tissues is lacking. Hence, the mechanical properties of fetal tissues should be quantified to design robotic devices that facilitate computer-assisted fetal surgery.     

不同胎龄胎儿半月板形态结构的光镜观察

目的 :研究不同胎龄胎儿半月板形态结构特点。方法 :半月板水平面、冠状面常规切片 ,HE染色。结果 :得到了胎儿半月板的形态、细胞、纤维、血管、表面被覆物的有关材料。结论 :胎儿半月板表面并不平坦 ,随胎龄增长 ,其胶原纤维逐渐增多而细胞密度减小 ,胎儿半月板血管丰富 ,有滑膜被覆。     

Effect of fetal breathing movements on fetal cardiac hemodynamics.

Maximum flow velocity waveforms were studied at atrioventricular and outflow tract level in 12 cases during fetal breathing activity and in 12 cases during fetal apnea matched for maternal and gestational age and maternal parity. Gestational age ranged between 27 and 40 weeks (median 30 weeks). All flow velocity waveforms were obtained using a mechanical sector scanner with a pulsed Doppler system (carrier frequency 3.5 MHz). Time-averaged flow velocities were clearly different between inspiration and expiration at all four recording levels, reflecting changes in venous return as a result of fluctuations in intrathoracic pressure during fetal breathing activity. Percentage change between inspiration and expiration at outflow tract level was positively correlated with gestational age. Time-averaged flow velocity at mitral level and ascending aorta level was significantly higher during fetal breathing activity than during apnea, suggesting increased shunting of blood flow through the foramen ovale. Acceleration time at outflow tract level demonstrated very little change relative to inspiration and expiration.     

胎儿颜面部的产前超声研究

目的 探讨宫内胎儿颜面部的超声表现与显示手法，提高产前超声对胎儿颜面部正常结构及畸形的认识。方法 选择2000年8月至2002年6月在我院行彩超产前检查的连续病例4200例，确定胎位后，对每一胎儿颜面部均进行冠状、矢状及横切面扫查。结果 99．62％(4184例)的胎儿颜面部各个结构均能够通过常规胎儿颜面部冠状切面、矢状切面、横切面正确显示，其深部骨性结构大部分亦能清楚显示，但硬腭与软腭不能显示。检出各种颜面部畸形29例78个，总检出率89．66％，漏诊7例9个(10．34％)，均经产后或引产证实。产前超声诊断胎儿颜面部畸形的敏感性、特异性、准确性、阳性预告值和阴性预告值分别为85．29％，99．95％，99．83％，93．55％和99．88％。结论 常规二维超声产前对胎儿颜面部大部分表面结构与深部骨性结构均能清楚显示，是显示胎儿颜面部结构与诊断胎儿颜面部畸形的可靠影像诊断方法。     

超声检测胎儿肝静脉频谱在胎儿期外收缩诊断中的价值

目的评价超声检测胎儿肝静脉频谱在胎儿期外收缩诊断及预后判断中的价值。方法 139例心律不齐胎儿,超声检查其肝静脉和行超声心动图检查,分别于2周后、分娩时和出生后3 d内复查。结果超声检查示124例(89.8%)胎儿室上性期外收缩,15例(10.2%)室性期外收缩;分娩时室上性期外收缩14例(11.3%),室性期外收缩3例(20.0%);出生后3d内16例心律恢复正常,1例室上性期外收缩发展为室上性心动过速。结论超声检测胎儿肝静脉频谱可鉴别室上性期外收缩与室性期外收缩,室性期外收缩更易在整个妊娠期持续存在,只有极少数期外收缩病例发展为心动过速或伴有先天性心脏畸形。     

胎儿超声生物学指标的Z-评分值在评估胎儿生长发育中的应用研究

摘 要 目的 探讨孕中、晚期超声生物学指标的Z-评分对评估胎儿生长发育的应用价值。方法 选取我院单胎孕妇中,筛查出巨大儿（A组）103例,胎儿生长受限（B组）48例,合并妊娠期糖尿病而血糖控制满意、出生体质量正常儿（C组）169例分别作为观察组,正常妊娠、胎儿体质量正常的196例为正常对照组。回顾分析中孕期（20+1～24周）、晚孕早期（28+1～33周）、晚孕晚期（34+1周～分娩）三个阶段的生长参数,包括胎儿双顶径（BPD）及头围（HC）、腹围（AC）、股骨长（FL）、头腹围比值（HC/AC）、腹围的Z-评分（AC的Z-评分）、头腹围比值的Z-评分（HC/AC的Z-评分）,比较不同阶段两组间各生长参数的差异、GDM的巨大儿与非GDM的巨大儿间的差异。结果 在中孕期、晚孕早期、晚孕晚期三个阶段,A组腹围的Z-评分值明显大于正常对照组、B组腹围的Z-评分明显小于正常对照组（P＜0.05）,且随孕龄的增加, A组、B组腹围的Z-评分值与正常对照组的偏离度进行性加大。C组在中孕期、晚孕早期腹围的Z-评分值与正常对照组无明显差别,仅在晚孕晚期其腹围的Z-评分值略高于正常对照组（P=0.045）。GDM的巨大儿组与非GDM的巨大儿组在体型上存在差异,表现为晚孕后期,GDM的巨大胎儿组头腹围比的Z-评分值小于非GDM的巨大儿组（P＜0.05）。传统超声生物学指标中,在中孕期（20+1～24周）只有A组的AC与正常对照组有差异、B组与正常组无明显差异。晚孕早期、晚孕晚期两阶段A组、B组BPD、HC、AC、FL、HC/AC均与正常对照组有差异（P＜0.05）,但无法直观判断各指标与正常对照组的偏离程度。结论：超声生物学指标的Z-评分有助于更准确定量评估胎儿宫内生长发育状况,在诊断胎儿宫内生长发育异常以及动态观察随访中有一定临床应用价值,值得推广。     

Human fetal brain imaging by magnetoencephalography: verification of fetal brain signals by comparison with fetal brain models

Fetal magnetoencephalogram (fMEG) is measured in the presence of a large interference from maternal and fetal magnetocardiograms (mMCG and fMCG). This cardiac interference can be successfully removed by orthogonal projection of the corresponding spatial vectors. However, orthogonal projection redistributes the fMEG signal among channels. Such redistribution can be readily accounted for in the forward solution, and the signal topography can also be corrected. To assure that the correction has been done properly, and also to verify that the measured signal originates from within the fetal head, we have modeled the observed fMEG by two extreme models where the fetal head is assumed to be either electrically transparent or isolated from the abdominal tissue. Based on the measured spontaneous, sharp wave, and flash-evoked fMEG signals, we have concluded that the model of the electrically isolated fetal head is more appropriate for fMEG analysis. We show with the help of this model that the redistribution due to projection was properly corrected, and also, that the measured fMEG is consistent with the known position of the fetal head. The modeling provides additional confidence that the measured signals indeed originate from within the fetal head.     

Normal ultrasonic fetal growth ratios evaluated in cases of fetal disproportion

During a 2-year period, 5476 normal routine obstetrical ultrasound investigations were performed in the 2nd trimester (16th to 20th week). Data on biparietal diameter (BPD), abdominal diameter (AD) and femur length (FL) have been obtained from this material. Ratios between BPD/AD and BPD/FL have been calculated, and from these ratios, graphs were constructed. Only nine normal fetuses (0.2%) were found to be outside mean +/- 3 SD, and none of the normal cases were +/- 4 SD, so this is perhaps a better guideline for those warranting further investigation. To evaluate if these ratios could better reflect disproportional fetal growth, three cases of triploidy and four cases of dwarfism were tested against these ratios. Triploidy was obvious on the BPD/AD graph and dwarfism on the BPD/FL graph. The ratios were not found to be conclusive in the intrauterine diagnosis of trisomy 21 or of trisomy 18, as only 4 of 17 cases were obvious on the graphs.     

根据胎儿体积模型超声预测胎儿体重

目的探讨胎儿体积模型推导超声预测胎儿估计体重（ＥＦＷ）的公式,并验证其准确性。方法根据胎儿体积模型,胎头重量与头围（ＨＣ）３成比例,胎儿躯干重量与腹围（ＡＣ）２×股骨长度（ＦＬ）成比例,以１９９５～１９９６年２４５例胎儿的超声结果经多元线性回归分析推导出比例常数和新公式：ＥＦＷ＝０．０２６１×ＨＣ３＋０．３０４０８×ＡＣ２×ＦＬ。１９９６～１９９８年应用新公式预测３４１例胎儿的出生体重以验证其准确性,并与Ｓｈｅｐａｒｄ公式比较。结果新公式和Ｓｈｅｐａｒｄ公式的平均相对误差±标准差分别为（３．９±２．９）％和（５．８±４．１）％（Ｐ＜０．０５）,新公式ＥＦＷ与出生体重间有明显相关性（ｒ＝０．９３３,Ｐ＜０．００１）。结论新公式在一定体重范围内（２０００～４５００ｇ）可准确预测胎儿体重。     

胎肝的免疫活性

应用酶组织化学和免疫组织化学方法,观察12例4～9月胎肝组织中的T淋巴细胞和树突状细胞,并用2例成人标本作对照。结果发现胎肝与成人肝比较,其免疫活性并不弱。用组织包埋方法进行动物实验也证实了这一点。     

Estimation of fetal weight by ultrasonic measurement of several fetal growth parameters

Fetal biparietal diameter (BPD) and head, chest and abdominal circumferences (HC, CC, AC) were measured by means of real-time B-scan echography. The study population consisted of 198 patients who were hospitalized at Tohoku University Hospital. All live-born infants were delivered within 48 hr after ultrasonic examination. This study was intended to establish criteria for diagnosis of fetuses weighing more than 2,500 g by means of a single ultrasonic measurement of several different fetal growth parameters. When estimated diameter of BPD exceeded 9.0 cm, 96.1% of the infants weighed more than 2,500 g. In all cases in which HC, CC, and AC exceeded 30 cm, the infants weighed more than 2,500 g. Finally, a multiple regression equation was constructed for estimation of birth weight by the values of fetal BPD, HC, CC and AC. The prediction error between prospective birth weight given by this formula and actual birth weight was +/- 200 g. The present method for estimation of fetal weight is simple and useful in obstetrical clinic.     

胎儿侧脑室增宽的超声与MRI评估一致性分析

目的 评价超声和MRI测量胎儿侧脑室宽度和诊断侧脑室增宽的一致性。方法 回顾性分析200胎胎儿头颅轴位声像图和冠状位MRI测量的双侧侧脑室宽度,评价两种检查方法测量的一致性和诊断侧脑室增宽的一致性（采用κ系数）,评价不同MRI医师间测量侧脑室宽度的一致性（采用ICC）。结果 超声和MRI测量侧脑室1（宽度较宽的侧脑室）、侧脑室2（宽度较窄的侧脑室）宽度的一致性很好（ICC=0.98、0.96）,超声和MRI诊断侧脑室增宽的一致性很好（κ>0.8）。2名MRI医师测量侧脑室1、侧脑室2宽度的一致性很好（ICC＝0.999、0.997）。结论 超声与MRI测量侧脑室宽度和诊断侧脑室增宽具有很好的一致性。