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Preterm birth is often associated with impaired brain development. The state and expected progression of preterm brain development can be evaluated using quantitative assessment of MR images. Such measurements require accurate segmentation of different tissue types in those images. This paper presents an algorithm for the automatic segmentation of unmyelinated white matter (WM), cortical grey matter (GM), and cerebrospinal fluid in the extracerebral space (CSF). The algorithm uses supervised voxel classification in three subsequent stages. In the first stage, voxels that can easily be assigned to one of the three tissue types are labelled. In the second stage, dedicated analysis of the remaining voxels is performed. The first and the second stages both use two-class classification for each tissue type separately. Possible inconsistencies that could result from these tissue-specific segmentation stages are resolved in the third stage, which performs multi-class classification. A set of T1- and T2-weighted images was analysed, but the optimised system performs automatic segmentation using a T2-weighted image only. We have investigated the performance of the algorithm when using training data randomly selected from completely annotated images as well as when using training data from only partially annotated images. The method was evaluated on images of preterm infants acquired at 30 and 40 weeks postmenstrual age (PMA). When the method was trained using random selection from the completely annotated images, the average Dice coefficients were 0.95 for WM, 0.81 for GM, and 0.89 for CSF on an independent set of images acquired at 30 weeks PMA. When the method was trained using only the partially annotated images, the average Dice coefficients were 0.95 for WM, 0.78 for GM and 0.87 for CSF for the images acquired at 30 weeks PMA, and 0.92 for WM, 0.80 for GM and 0.85 for CSF for the images acquired at 40 weeks PMA. Even though the segmentations obtained using training data from the partially annotated images resulted in slightly lower Dice coefficients, the performance in all experiments was close to that of a second human expert (0.93 for WM, 0.79 for GM and 0.86 for CSF for the images acquired at 30 weeks, and 0.94 for WM, 0.76 for GM and 0.87 for CSF for the images acquired at 40 weeks). These results show that the presented method is robust to age and acquisition protocol and that it performs accurate segmentation of WM, GM, and CSF when the training data is extracted from complete annotations as well as when the training data is extracted from partial annotations only. This extends the applicability of the method by reducing the time and effort necessary to create training data in a population with different characteristics. [ABSTRACT FROM AUTHOR]

Cortical folding mainly takes place in the third trimester of pregnancy and may therefore be influenced by preterm birth. The aim of this study was to evaluate the development of specific cortical structures between early age (around 30 weeks postmenstrual age) and term-equivalent age (TEA, around 40 weeks postmenstrual age) in 71 extremely preterm infants, and to associate this to clinical characteristics and neurodevelopmental outcome at two years of age. First, analysis showed that the central sulcus (CS), lateral fissure (LF) and insula (INS) were present at early MRI in all infants, whereas the other sulci (post-central sulcus [PCS], superior temporal sulcus [STS], superior [SFS] and inferior [IFS] frontal sulcus) were only seen in part of the infants. Relative growth from early to TEA examination was largest in the SFS. A rightward asymmetry of the surface area was seen in development between both examinations except for the LF, which showed a leftward asymmetry at both time points. Second, lower birth weight z-score, multiple pregnancy and prolonged mechanical ventilation showed negative effects on cortical folding of the CS, LF, INS, STS and PCS, mainly on the first examination, suggesting that sulci developing the earliest were the most affected by clinical factors. Finally, in this cohort, a clear association between cortical folding and neurodevelopmental outcome at two years corrected age was found, particularly for receptive language. [ABSTRACT FROM AUTHOR]

Background and aim Disturbances in cerebral oxygenation saturation (SO 2 ) have been linked to adverse outcome in adults, children, and neonates. In intensive care, the cerebral SO 2 is increasingly being monitored by Near-InfraRed Spectroscopy (NIRS). Unfortunately NIRS has a limited penetration depth. The “modified T 2 -prepared Blood Imaging of Oxygen Saturation” (T 2 -BIOS) MR sequence provides a step towards full brain SO 2 measurement. Materials and methods Tissue SO 2 , and venous SO 2 (S v O 2 ) were obtained simultaneously by T 2 -BIOS during a respiratory challenge in ten healthy volunteers. These two measures were compared to SO 2 that was obtained by a single probe MR-compatible NIRS setup, and to cerebral blood flow and venous SO 2 that were obtained by arterial spin labelling and T 2 -TRIR, respectively. Results SO 2-T2-BIOS and SO 2-NIRS had a mean bias of − 4.0% (95% CI − 21.3% to 13.3%). S v O 2-T2-BIOS correlated with SO 2-NIRS (R 2 = 0.41, p = 0.002) and S v O 2-T2-TRIR (R 2 = 0.87, p = 0.002). In addition, SO 2-NIRS correlated with S v O 2-T2-TRIR (R 2 = 0.85, p = 0.003) Frontal cerebral blood flow correlated with SO 2-T2-BIOS (R 2 = 0.21, p = 0.04), but was not significant in relation to SO 2-NIRS . Discussion/conclusion Full brain SO 2 assessment by any technique may help validating NIRS and may prove useful in guiding the clinical management of patient populations with cerebral injury following hypoxic-ischaemic events. The agreement between NIRS and T 2 -BIOS provides confidence in measuring cerebral SO 2 by either technique. As it stands now, the T 2 -BIOS represents a novel idea and future work will focus on improvements to make it a reliable tool for SO 2 assessment. [ABSTRACT FROM AUTHOR]

Diffusion tensor imaging (DTI) is frequently used to assess brain development in preterm infants. This study investigates maturational changes in diffusivity measures in 122 regions of the brain between 30 and 40 weeks postmenstrual age (PMA) using the neonatal atlas of Oishi and colleagues (Oishi et al., 2011). Forty infants without cerebral injury and with normal neurodevelopmental outcome were selected from a cohort of preterm infants (gestational age < 28 weeks), scanned longitudinally at 30 and 40 weeks PMA. Fractional anisotropy (FA) changed significantly in 84 brain regions, with the largest increase in the central brain regions; by contrast, the cortical brain regions showed a decrease in FA. Mean, radial and axial diffusivity all showed a clear decrease in the majority of brain regions. This study provides longitudinal reference diffusivity values in a cohort of extremely preterm infants, showing a central to peripheral and posterior to anterior directed gradient, in line with our current understanding of brain maturation, and adding to this knowledge. This study further elucidates brain maturation in preterm infants during the last 10 weeks prior to term equivalent age. The presented values can be used as a reference for assessing brain development in other cohorts, when investigating the effects of brain injury in this vulnerable period, and to evaluate the effect of future neuroprotective strategies. [ABSTRACT FROM AUTHOR]