Functional Magnetic Resonance Imaging Of Fetus

Partâ… The study of feasibility of MRS of fetal brainObjective To investigate the feasibility of single voxel ¹H magnetic resonancespectroscopy in fetal brain combination with fetal dynamic magnetic resonance imaging.Methods 50 cases of fetuses were divided into three groups; polyhydramnios (n=6),normal amount of amniotic fluid (n=21) and oligohydramnios (n=23). Gestatinal weeksranged from 20 weeks to 40 weeks, with median week of 32.6 weeks.Fetal dynamic MRIwere performed sagittally using SSFSE to observe fetal brain motion.On the basis ofsite-specific three planes, Point resolved spectroscopy sequence (PRESS) was used forsingel voxel ¹H MRS (TE=144ms) and the view of interest (VOI) was located in bothcerebral hemisphere at the level of semiovale centrum and basal ganglia with respiratorytrigger technique. Results The index of amniotic fluid of polohydramnios,normalamount of amniotic fluid and oligohydramnios were (8.0±0.7) cm,(5.7±1.4)cm and(3.8±1.4) cm, respectively.there is significantly statistical difference (F=17.95, P＜0.001).In group of polohydramnios, dynamic MRI can clearly display frequent motion withmultiple regional turnover, extention and turning of head. The resolution of MRS was low,each metabolin could not been distinguished Conclusion ¹H MRS in fetal brain is feasible.the achievement ratio is zero, In group of normal amount of amniotic fluid ,fetal headmotion decreased, each metabolin cound be distinguished with much noise.and theresolution is slightly low, the achievement ratio is 42.85% (9/21). In group ofoligohydramnios, fetal head motion is restricted and the achievement ratio is 95.65%(22/23),there is a significantly statistical difference between the group of oligohydramniosand normal amniotic fluid (X²= 14.69, P＜0.05 ). Conclusion MRS of fetal head is feasibleand can play an important role in the evaluation of fetal brain development and diagnosisof disease. Partâ…¡Normal MRS of fetal brain maturationObjective To explore the metabolic level change of normal fetal brain with increasedgestational age. Methods 12 cases of gravidas during the second trimester and 23 cases ofgravidas during the third trimester consistant with the standard of investigation wereincluded into the study.Gestatinal weeks ranged from 20 weeks to 40 weeks, with medianweek of 34.6 weeks Cranial axial, sagittal and coronal planes T2WI were performed usingSSFSE within 1-2 days after US examinantion. On the basis of site -specific three planes,Point resolved spectroscopy sequence(PRESS) was used for singel voxel 1HMRS(TE=144ms and 35ms) using respiratory triggered technique and the view ofinterest(VOI) was located in both cerebral hemisphere at the level of semiovale centrumand basal ganglia .Measure value of spectra was automaticly provided, the metabolities inthe spectra included : N-acetylaspartate(NAA),Choline,com-pounds(Cho),Creatinecompounds(Cr),myo-inositol(mI),glutamate and glutamine(Glx) and so on. ResultsThere is no significantly statistical diffenence between the study group and the controlgroup about the head circumference,biparietal diameter,abdominal circumference andfemur length. Brain MRI and postnatal examination were normal ,Similar to the brain ofpostnatal neonates, MRS of the fetal brain showed three dominant resonance atTE=144ms,the highest choline peak at 3.2ppm, the creatirie peak at 3.0ppm and the NAApeak at 2.0ppm. Before 34 weeks, creatine peak is the second highest and after 34weeks,NAA is the sceond one. Five dominant resonance: MI, Cho, Cr, Glx and NAA wereobserved at the short echo time(TE= 35ms). During brain maturation in utero, at a longecho time (TE = 144 ms), a significant increase in NAA/S (P＜0.007, r2 =0. 20), and areduction in Cho/S (P=0.005, r2=0.22) is Seen.No significant increasein Cr/S (P = 0.96,r2=0.001) is detected. Lactate is not foundin normal, a significant increase in NAA/S (P=0.05, r2 = 0.21). No significant increase in Cr/s (P = 0.2, r2 = 0.049), A significant asignificant reduction in the MI/S (P = 0.045, r2 = 0.12) and Cho/S (P = 0.014, r2=0.17)ratio with progressing GA were observed at a short echo time. Conclusion 1H MRS infetal brain is feasible, the achievement ratio using respitory gating technique. Partâ…¢Development of normal fetal brain by MRI withsingle-shot fast spin echo and diffusion tensor imagingObjective To evaluate normal maturation of the fetal brain combination with SSFSE andDTI. Methods The normal brains of 17 fetuses of 20-39 weeks gestational age wereexamined in utero with SSFSE series and DTI, gray and white matter differentiation,Gyrus maturation were evaluatedwith respect to gestational age, the data measured inADC maps and FA maps in different regions of normal fetal brain were analyzedstatistically. Results (1)At 20-23 weeks, the norma structure has been formed andtypical five layers were seen during the period .and three layers during 24-26weeks ,after27 weeks, only two layer were found.the brain had a smooth surface at about 20 weeksand lateral fissure could be found, the circuity and inner fovea of cortex were found withprogressive gestational weeks followed by gyrus and sulcus were formed and deepen, At30 weeks, sulcus and gyrus formation was observed in various regions of the brainparenchyma.(3)The mean ADC value was 1.83±0.3μm2/ms in frontal white matter,1.75±0.1μm2/ms in occipital white matter, 1.65±0.1μm2/ms in basal ganglia and2.9±0.6μm2/ms in cerebrospinal fluid, the difference between basal ganglia and both frontand occipital white matter was satistically significant (p＜0.05), a significant negativecorrelation between ADC value and gestational age could be found in frontal and occipitalwhite matter, as well as basal ganglia. Sensorimotor fibre could be tracted by the ventricleand bilateral sensorimotor could be clearly displayed in the hindlimb of interalcapsule .After 20 weeks, the fibre of genu and splenium could be tracted and FA value ofthem increase with progressive gestational weeks. Conclusion The change of brainparenchyma can be overallly and accurately assessed combination with SSFSE series andDTI. Partâ…£Three dimensional magnetic resonance imagingObjective To investigate the value of three dimensional magnetic resonance imaging indisplaying the normal and abnormal structure of fetus compared with theultrasonography(US). Methods fifty pregnant women (gestational age rangedfrom20～38 weeks, with a mean of 28.6 weeks.) with fetal malformations were performedwith conventional prenatal US and MRI, sixty-two fetuses with anomalies wereconformed by autopsy and follow-up. Axial, sagittal and coronal SSFSE T₂WIexamination by a 1.5T GE superconduting MR scanner within 1～2 days after USexaminations were performed, 41 cases were performed three dimensional MRI with fastimage employing steady-state acquisition (FIESTA), 9 cases were performed threedimensional colon image with fast spoiled gradient echo(FSPGR),imaging postprocessingwere performed on SUN workstation,the MR and US appearances of fetal malformationswere compared to each other and autopsy. Results fifty-eight cases of fetalmalformations were verified by autopsy and follow-up ,includeing anacephaly(n=8),encephalomeningocele(n=3), micro-cephaly(n=1), cystic lymphangioma(n=9), conjoinedtwins(n=4), congenital diaphragmatic hernia(n=5), congenital (n=4), omphalocele (n=6),gastro-schisis(n=4), body stalk abnormality (n=1), equinovarus foot (n=5), the sensi-tivityand specifity of 3D-US and 3D-MRI were 89.66%(52/58) and 98.11% (52/53) versus93.10% and 98.18%, ther was no statistically significance between the two modalities, but3D-MRI have larger FOV, higher tissue resolution and can demonstrate fetal surface andlesions with multiple planes. Conclusions three dimensional MRI can perspicuouslyperform surfacing, directly display surface character ,solid figure and position relation.