Objectives: The usefulness of ultrafast sequence called balanced turbo field echo sequence with sensitivity encoding(sBTFE),that has been used routinely in a clinical practice is not well established in fetal brain imaging in vivo.We investigated the usefulness of sBTFE sequence in the achievement of a high quality image of the fetal brain and whether sBTFE might improve diagnostic confidence.Using sBTFE we further measured the white matter signal intensities(SI)in fetal brains across the spectrum of gestational age that could provide indirect information on the white matter alteration in the fetal brain.Methods: Brains of 160 physiological singleton fetuses in unsedated conditions ranging from 21 to 39 gestational week(GW)were imaged with sBTFE sequence at 1.5 T scanner.Signal heterogeneity correction for the variations in the sensitivities of abdominal phased array coils was done using…what?(how did you correct for this?)..Signal intensity(SI)values from 15 regions of interest(ROI)were calculated(using what,do you have a name of algorithm?),and SI ratios(SIR)were determined by scaling SI from respectibe ROIs by SI from Cereberospinal fluid.We grouped fetal brains to four groups A-D based on the gestational age.We calculated SIRs for the bilateral prefrontal,occipital,temporal,parietal and precentral white matter regions and thalamus,Cerebellum and pons separately for each gestational age group.Group-wise differences in SIRs within a forementioned ROIs were assessed using analysis of covariance.Results: sBTFE imaged the white matter in the fetal brain with optimized diagnostic confidence(3.35 ± 0.42)because of its excellent CSF-white matter-gray matter contrast and a high spatial resolution.150 fetal brain images were finally enrolled into next analysis with only10 fetuses excluded due to their poor image quality with the diagnostic confidence score less than 3.0.In group-wise analysis of SIRs in across the gestational spectrum,and the prefrontal zone was characterized by lower SIR than other subplate zones during GW 21-23.This finding could be explained by the germinal matrix being present exclusively in the frontal lobe white matter at this time point.Conversely,we found a higher SIR in the temporal lobes,Cerebellar white matter and pons as compared to the other brain regions in gestational week,which was consistent the pattern of heterogeneous alteration in different brain regions in other studies.Conclusions: This study used a relative large cohort to demonstrate differences in SIR of the white matter in the fetal brain at the different stages of its alteration using otherwise routinely used clinical sBTFE sequence.White matter SIR would differ with respect to the gestational age,reflecting the temporal order when and where the germinal matrix migrates and how myelination progresses.