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Nigel L Kennea

Publications and source records attributed to Nigel L Kennea.

5 recordsLinked to original sources
PubMed2003

Diffusion-weighted imaging of the brain in preterm infants with focal and diffuse white matter abnormality.

OBJECTIVE: The most common finding on magnetic resonance imaging (MRI) of the brain in preterm infants at term-equivalent age is diffuse excessive high signal intensity (DEHSI) in the white matter. It is unclear whether DEHSI represents a biological abnormality. This study used diffusion-weighted imaging (DWI) to compare apparent diffusion coefficient (ADC) values in DEHSI with infants with normal imaging and those with overt brain damage to determine whether DEHSI shows the diffusion characteristics of normal or abnormal tissue. METHODS: MRI, using conventional and diffusion-weighted imaging (DWI), was performed in 50 preterm infants at term-equivalent age using a 1.5 Tesla MR scanner. The infants were divided into 3 groups on the basis of their MRI results: 1) normal white matter, 2) DEHSI, or 3) overt white matter pathology. ADC values were measured in the frontal, central, and posterior white matter at the level of the centrum semiovale. ADC values in the 3 groups of preterm infants were compared using a 1-way analysis of variance with a Bonferroni test for multiple comparisons. RESULTS: ADC values were significantly higher in infants with DEHSI and infants with overt white matter pathology than in infants with normal white matter. There was no significant difference between ADC values in infants with DEHSI and those with overt white matter pathology. CONCLUSIONS: This study provides objective evidence that DEHSI represents diffuse white matter abnormality.

Body Water↗
PubMed2003

T2 relaxation values in the developing preterm brain.

BACKGROUND AND PURPOSE: MR imaging is increasingly used to assess maturation and disease in the preterm brain. Knowledge of the changes in T2 values with increasing postmenstrual age (PMA) will aid image interpretation and help in the objective assessment of maturation and disease of the brain in infants. The aim of this study was to obtain T2 values in the preterm brain from 25 weeks' gestational age (GA) until term-equivalent age in infants who had normal neurodevelopmental findings at a minimum corrected age of 1 year. METHODS: The study group consisted of 18 preterm infants, born at 33 weeks' GA or sooner. The median GA of the infants at birth was 27 weeks (range, 23-33 weeks), and the median PMA at imaging was 31 weeks (range, 25-41 weeks). T2 measurements were obtained using a 1.0-T MR system and a four-echo pulse sequence (TR/TE, 2500/ 30, 60, 110, and 600). T2 values were measured in the thalami, lentiform nuclei, frontal white matter, occipital white matter, and central white matter at the level of the centrum semiovale. RESULTS: A significant negative linear correlation between T2 values and PMA was demonstrated in the lentiform nuclei (P =.003), frontal white matter (P <.0001), occipital white matter (P <.0001), and central white matter at the level of the centrum semiovale (P <.0001). T2 values were not significantly reduced with increasing PMA in the thalami (P =.06). CONCLUSION: T2 values decrease with increasing PMA in the preterm brain.

Birth Weight↗
PubMed2002

Magnetic resonance imaging of lung water content and distribution in term and preterm infants.

An increase in lung liquid may contribute to respiratory disease in preterm infants. Uneven distribution of lung liquid may cause heterogeneity in the lung disease seen in these infants. We used magnetic resonance imaging to investigate lung water content and distribution in 16 preterm (24-31 weeks) and 9 term infants in the first week of life. Images of lung parenchyma were examined and relative proton density quantified to give an index of lung water. Lung water content and distribution were compared between preterm and term infants, and in preterm infants regional signal distribution between dependent and nondependent lung on T1 weighted images was also compared after turning between prone and supine positions. Relative proton density was higher in preterm than in term lung (p < 0.008) and greater in dependent than in nondependent regions, particularly in the preterm (p < 0.001). Repositioning preterm infants rapidly redistributed signal intensities, with more even distribution lying prone than supine (p < 0.001). Small, low-signal regions were seen in the lung parenchyma in preterm but not in term infants, which may indicate peribronchial fluid or overdistension of compliant lung units. We conclude that lung water content is higher in preterm than in term infants and is associated with gravity-related changes consistent with dependent atelectasis.

Extravascular Lung Water↗
PubMed2002

Neural stem cells.

Neural stem cells (NSCs) have the ability to self-renew, and are capable of differentiating into neurones, astrocytes and oligodendrocytes. Such cells have been isolated from the developing brain and more recently from the adult central nervous system. This review aims to provide an overview of the current research in this evolving area. There is now increasing knowledge of the factors controlling the division and differentiation of NSCs during normal brain development. In addition, the cues for differentiation in vitro, and the possibility of transdifferentiation are reviewed. The discovery of these cells in the adult brain has encouraged research into their role during neurogenesis in the normal mature brain and after injury. Lastly other sources of neural precursors are discussed, and the potential for stem cells to be used in cell replacement therapy for brain injury or degenerative brain diseases with a particular emphasis on cerebral ischaemia and Parkinson's disease.

Adult↗