Neonatal neuroimaging: going beyond the pictures.

The cerebral ultrasound has been used many years for the diagnosis of brain lesions in term and preterm newborns. Major improvements were obtained by the combination of different imaging modalities such as Magnetic Resonance Imaging with the Diffusion Weighted Imaging (DWI) and the new quantitative Diffusion Tensor Imaging (DTI). The clinical use of MRI has been validated over some years especially to depict the perinatal asphyxia lesions in term newborns, but its use in order to diagnose the typical diseases of preterm babies is very recent and useful in identifying a marker able to predict neurological outcome. The imaging correlates for motor impairment are well recognized (periventricular white matter cavitations), but no any imaging correlate for cognitive impairment and neurobehavioral disorders. While DWI has been used in term newborns to identify the ischemic areas with restricted diffusion, it may be also used to characterize brain development in preterm infants with the Apparent Diffusion Coefficient (ADC) and may allow us to detect abnormalities responsible for the non-motor impairments. Recent datas showed that in infants without focal lesions higher ADC values in WM were associated with poorer neurodevelopmental assessment at 2 years. The DTI also allows to detect the Fractional Anisotropy (FA) that measures the microstructure. DTI can also be used to map the WM tracts in the immature brain and may be applied to understand the normal development or the response of the brain to injury. Some WM regions in the preterm brain have a lower FA suggesting that widespread WM abnormalities are present in preterms even in the absence of focal lesions. The complexity of the developing brain can be explained by the new tractography that can assess the connectivity of different WM regions and the association between structure and function, such as optic radiations microstructure and visual assessment score. Technological advances in neonatal brain imaging have made a major contribution to understand the neurobehavioral disorders of the developing brain that have the origin in the early structural cerebral organization and maturation.

[1]  Guoguang Fan,et al.  Potential of diffusion tensor MRI in the assessment of periventricular leukomalacia , 2006 .

[2]  F A Jolesz,et al.  Early detection of periventricular leukomalacia by diffusion-weighted magnetic resonance imaging techniques. , 1999, The Journal of pediatrics.

[3]  M A Rutherford,et al.  Magnetic resonance imaging of the brain in a cohort of extremely preterm infants. , 1999, The Journal of pediatrics.

[4]  J. Allsop,et al.  Relationship Between White Matter Apparent Diffusion Coefficients in Preterm Infants at Term-Equivalent Age and Developmental Outcome at 2 Years , 2007, Pediatrics.

[5]  R. Kikinis,et al.  Microstructural brain development after perinatal cerebral white matter injury assessed by diffusion tensor magnetic resonance imaging. , 2001, Pediatrics.

[6]  Carola van Pul,et al.  Fractional anisotropy in white matter tracts of very-low-birth-weight infants , 2007, Pediatric Radiology.

[7]  Joel R. Meyer,et al.  Serial Diffusion Tensor Imaging Detects White Matter Changes That Correlate with Motor Outcome in Premature Infants , 2007, Developmental Neuroscience.

[8]  Guido Gerig,et al.  Comparisons of regional white matter diffusion in healthy neonates and adults performed with a 3.0-T head-only MR imaging unit. , 2003, Radiology.

[9]  S. Maier,et al.  Microstructural Development of Human Newborn Cerebral White Matter Assessed in Vivo by Diffusion Tensor Magnetic Resonance Imaging , 1998, Pediatric Research.

[10]  Fabio Mosca,et al.  Probabilistic diffusion tractography of the optic radiations and visual function in preterm infants at term equivalent age. , 2008, Brain : a journal of neurology.

[11]  Mary A. Rutherford,et al.  Diffusion tensor imaging with tract-based spatial statistics reveals local white matter abnormalities in preterm infants , 2007, NeuroImage.

[12]  G. Molenaers,et al.  Quantitative diffusion tensor imaging in cerebral palsy due to periventricular white matter injury. , 2005, Brain : a journal of neurology.

[13]  Daniel Rueckert,et al.  Tract-based spatial statistics: Voxelwise analysis of multi-subject diffusion data , 2006, NeuroImage.

[14]  M. Moseley,et al.  In vivo MR tractography using diffusion imaging. , 2003, European journal of radiology.

[15]  Latha Srinivasan,et al.  Thalamo-cortical connectivity in children born preterm mapped using probabilistic magnetic resonance tractography , 2007, NeuroImage.

[16]  Fabio Mosca,et al.  Apparent diffusion coefficient determination in normal fetal brain: a prenatal MR imaging study. , 2003, AJNR. American journal of neuroradiology.

[17]  P C M van Zijl,et al.  Diffusion Tensor Imaging in Children with Periventricular Leukomalacia: Variability of Injuries to White Matter Tracts , 2007, American Journal of Neuroradiology.

[18]  M. Solaiyappan,et al.  Diffusion tensor imaging of periventricular leukomalacia shows affected sensory cortex white matter pathways , 2002, Neurology.

[19]  R C McKinstry,et al.  A prospective, longitudinal diffusion tensor imaging study of brain injury in newborns , 2002, Neurology.

[20]  J. Rose,et al.  Neonatal microstructural development of the internal capsule on diffusion tensor imaging correlates with severity of gait and motor deficits , 2007, Developmental medicine and child neurology.

[21]  M. Erb,et al.  Developing somatosensory projections bypass periventricular brain lesions , 2006, Neurology.

[22]  David J Larkman,et al.  Diffusion-weighted imaging of the brain in preterm infants with focal and diffuse white matter abnormality. , 2003, Pediatrics.

[23]  L. D. de Vries,et al.  Neonatal Diffusion-Weighted MR Imaging: Relation with Histopathology or Follow-Up MR Examination , 2001, Neuropediatrics.