Quantification of total fetal brain volume using 3D MR imaging data acquired in utero

Abstract

 Measurement of fetal brain volume from iuMR imaging is a relatively new area of investigation and has been derived from motion corrected ultrafast 2D imaging but there is limited published data due to small sample sizes. Fetal brain volumes can be derived from 3D iuMR acquisitions with a high degree of reproducibility using freehand segmentation. Our work demonstrated a quadratic model provided best fit to describe the changes of fetal brain growth in relation to gestational age, increasing from a Mean value of 22.5 cm 3 to 274.7cm 3 between 18 and 36 weeks gestation.2

Clinical applications of 3D volume MR imaging of the fetal brainin utero

“…Total brain parenchymal volume was calculated by adding the volumes of both cerebral hemispheres and the infratentorial structures but note those do NOT include the volume of the enclosed cerebral ventricles and therefore represent true brain ‘parenchymal’ volumes. The TPBV of these five cases were compared against our published normative data . In two cases (3 and 4), we show the importance of distinguishing between parenchymal volume and brain volume that includes the intraventricular compartment, and in case 5, we show the potential application of sub‐division of the brain structures to assist diagnosis.…”

“…All of those are also 2D datasets, and they may have some incremental diagnostic advantages in some situations, for example, T1‐weighted images show sub‐acute haemorrhage well and diffusion weighted images show acute infarction well in utero, as it does in post‐natally. We believe, however, that the most significant recent development in terms of improved clinical diagnosis is likely to be capacity to acquire 3D T2‐weighted datasets, which is now possible in ultrafast timescales . The major theoretical advantages of 3D images of the fetal brain over routine 2D iuMR imaging are as follows: Reduced partition thickness (1.0–1.2 mm) which improves out‐of‐plane resolution and hence the delineation of small anatomical structures. Reconstruction in any plane which improves the assessment of brain structures that are not in the natural orthogonal planes or if the 3D acquisition was not aligned perfectly with the natural orthogonal planes Improved assessment of developing sulcation/gyration from generated surface models Robust assessment of brain volume and other intracranial compartments …”

“…Our earlier publications described the methods involved in acquiring 3D data sets and deriving normative brain volume charts from normal fetuses . In this paper, we summarise our current techniques of creating images of the surfaces of fetal brains and estimates of total brain parenchymal volumes (TBPV), illustrate the potential value of these techniques in five cases and discuss potential research studies that will confirm or refute the diagnostic value.…”

Current state of MRI of the fetal brain in utero

“…Our group has been able to build up a database of normative volume data from 200 fetuses using this method (Fig. ) and this information has been vital to demonstrate how brain size is altered when abnormalities are present …”

“…Our group has been able to build up a database of normative volume data from 200 fetuses using this method (Fig. 14) 68 and this Note that there is a prominent choline peak at 23 weeks but the creatine and N-acetylaspartate peaks are barely discernible from the baseline. By 29 weeks the creatine and N-acetylaspartate peaks are much better resolved, with the N-acetylaspartate peaks being slightly smaller than the creatine, although that is reversed at 35 weeks.…”