Advanced Brain Imaging in Preterm Infants: A Narrative Review of Microstructural and Connectomic Disruption

Global trends in neonatal MRI brain neuroimaging research over the last decade: a bibliometric analysis

Background

Neuroimaging plays a central role in the evaluation, treatment, and prognosis of neonates. In recent years, the exploration of the developing brain has been a major focus of research for researchers and clinicians. In this study, we conducted bibliometric and visualization analyses of the related studies in the field of neonatal magnetic resonance imaging (MRI) brain neuroimaging from the past 10 years, and summarized its research status, hotspots, and frontier development trends.

Methods

The Web of Science core collection database was used as the literature source from which to retrieve the relevant papers and reviews in the field of neonatal MRI brain neuroimaging published in the Science Citation Index-Expanded from 2013 to 2022. VOSviewer and CiteSpace were used to conduct bibliometric and visualization analyses of the annual publication volume, countries, institutions, journals, authors, co-cited literature, and the overall distribution of keywords.

Results

We retrieved 3,568 papers and reviews published from 2013 to 2022. The number of publications increased during this period. The United States (US) and the United Kingdom were the largest contributors, with the US receiving the highest H-index and number of citations. The institutions that published the most were the University of London and Harvard University. The research mainly focused on cerebral cortex, brain tissue, brain structure network, artificial intelligence algorithm, automatic image segmentation, and premature infants.

Conclusions

This study reveals the research status and hotspots of magnetic resonance imaging in the field of neonatal brain neuroimaging in the past decade, which helps researchers to better understand the research status, hotspots, and frontier development trends.

Quantification of stress exposure in very preterm infants: Development of the NeO-stress score

BACKGROUND

Stress during treatment at the Neonatal Intensive Care Unit (NICU) has long-term negative consequences on preterm infants' development.

AIMS

We developed an instrument suited to validly determine the cumulative stress exposure for preterm infants in a NICU.

STUDY DESIGN

This survey study made use of two consecutive questionnaires.

SUBJECTS

NICU nurses and physicians from the nine NICUs in the Netherlands.

OUTCOME MEASURES

First, respondents rated the relevance of 77 items encompassing potentially stressful procedures, commented on their comprehensibility and the comprehensiveness of the list. We calculated the content validity per item (CVI-I) and included only the relevant items in a second questionnaire in which the participants rated the stressfulness from 0 (not stressful) to 10 (extremely stressful). A stressfulness index - representing the median score - was calculated for each included item.

RESULTS

Based on the CVI-I of the 77 items, step 1 resulted in 38 items considered relevant to quantify stress in preterm infants during the first 28 days of life. This list of 38 items exists of 34 items with a CVI-I if 0.78 or higher, one of these items was split into two items, and three items were added to improve comprehensiveness. The stressfulness index ranged from five to nine.

CONCLUSIONS

The NeO-stress score consists of stressful items including their severity index and was developed to determine cumulative stress exposure of preterm infants. Evaluating the cross-cultural validity, correlating it to behavioural and biological stress responses, and evaluating its ability to predict preterm infants at risk for the negative effects following stress might expand the possibilities for this instrument.

Assessment of brain two-dimensional metrics in infants born preterm at term equivalent age: Correlation of ultrasound scans with magnetic resonance imaging

CONTEXT

Developing brain imaging is a critical subject for infants born preterm. Impaired brain growth is correlated with poor neurological outcomes, regardless of overt brain lesions, such as hemorrhage or leukomalacia. As magnetic resonance imaging (MRI) remains a research tool for assessing regional brain volumes, two-dimensional metrics (2D metrics) provide a reliable estimation of brain structures. In neonatal intensive care, cerebral ultrasound (cUS) is routinely performed to assess brain integrity. This prospective work has compared US and MRI accuracy for the measurement of 2D brain metrics and identification of overt injuries.

METHODS

MRI and cUS were performed at term equivalent age (TEA) in infants born before 32 weeks of gestation (GW). Demographical data and results of serial cUS (Neonatal Intensive Care Unit [NICU]-US) performed during hospitalization were gathered from medical charts. Blinded, experienced senior doctors reviewed the scans for both standard analysis and standardized, 2D measurements. The correlation of 2D metrics and inter-/intraobserver agreements were evaluated using Pearson's coefficient, Bland-Altman plots, and intraclass coefficient (ICC), respectively.

RESULTS

In total, 102 infants born preterm were included. The performance of "TEA-cUS and NICU-cUS" when compared to "TEA-MRI and NICU-cUS" was identical for the detection of high-grade hemorrhages and close for low-grade ones. However, TEA-MRI only detected nodular lesions of the white matter (WM). No infant presented a cerebellar infarct on imaging. Intra- and inter-observer agreements were excellent for all 2D metrics except for the corpus callosum width (CCW) and anteroposterior vermis diameter. MRI and cUS showed good to excellent correlation for brain and bones biparietal diameters, corpus callosum length (CCL), transcerebellar diameters (TCDs), and lateral ventricle diameters. Measures of CCW and vermis dimensions were poorly correlated.

CONCLUSION AND PERSPECTIVE

The cUS is a reliable tool to assess selected 2D measurements in the developing brain. Repetition of these metrics by serial cUS during NICU stay would allow the completion of growth charts for several brain structures. Further studies will assess whether these charts are relevant markers of neurological outcome.