2001). Indeed, late OL progenitors,

known as the predominant population of OL during this period, are suspected to be a potential target for injury in PVL (Back et al. 2001). While promising, this pilot study only provides a proof of concept obtained in one highly selected DTI fetal database with no or minimal motion artifacts. Generalization of this method will Inhibitors,research,lifescience,medical require further methodological approaches mostly related to motion corrections to get reliable normative data in a large cohort of fetuses and to study developmental disorders (Rousseau et al. 2005, 2006; Jiang et al. 2007, 2009). Docetaxel in vivo limitations Several technical limitations have to be acknowledged thanks to the interpretation of the results obtained in this pilot study. The major limitation is relative to the fetus motions during acquisition and the way to handle Inhibitors,research,lifescience,medical such a problem. As demonstrated by Hayat et al. (2010), there is an important reduction of fetus motion between 23 GW and Inhibitors,research,lifescience,medical 36 GW, though attributable to decreased intrauterine space and immobilization of the fetal head in the maternal pelvis in the cephalic presentation (Kasprian et al. 2008). In this study, 85% of selected fetuses were in cephalic presentation. Recent very interesting

approaches have been proposed to postprocess DTI data in moving subjects, by rotating appropriately after image registration the directions of the diffusion-sensitizing gradients (Jiang Inhibitors,research,lifescience,medical et al. 2007, 2009). In the present study, we did not use such

an approach while we decided to select strictly in quite a large sample of data (61 in utero fetuses acquisitions), only the exams with very limited or absent motion observed on Inhibitors,research,lifescience,medical coronal, sagittal, and axial views of b = 0 images. Motion was evaluated by two independent readers (EZ, NG). Only a very small number of data survived to this screening (17 out of 61; 28%). Accordingly to minimal fetus motion in this dataset, we obtained sufficient SNR (about 14) on b = 0 s/mm2 images to obtain relevant FA and ADC maps as well as coherent fiber pathways reconstructed by tractography. Finally, each these reconstructed tract was evaluated by a second expert in fetal neuroradiology (NG) based on anatomical landmarks. In case of bad scoring, tracking was redone once, and finally not considered if not approved by the expert at that time. Only a small percentage of tracts were rejected during this second selection (4%; five out of 119). Reconstruction of the validated selected tracts could be then considered as robust. It is also important to note that between 23 GW and birth, previous histological studies have demonstrated the presence of the tracts studied in this work (Huang et al.