Neonatal Intensive Care Unit-Fondazione IRCCS Ospedale Maggiore Policlinico Mangiagalli e Regina Elena University Department of Mother and Infant Sciences, Univeristy of Milan, Italy.
Early Hum Dev. 2009 Oct;85(10 Suppl):S75-7. doi: 10.1016/j.earlhumdev.2009.08.022. Epub 2009 Sep 29.
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.
脑部超声已被用于诊断足月和早产儿的脑部病变多年。通过磁共振成像与弥散加权成像（DWI）和新的定量弥散张量成像（DTI）等不同成像方式的结合，取得了重大进展。MRI 的临床应用已得到多年验证，特别是在描绘足月新生儿围产期窒息病变方面，但它在诊断早产儿典型疾病方面的应用非常新，有助于识别能够预测神经发育结果的标志物。与运动障碍相关的影像学表现已得到充分认识（脑室周围白质空洞），但与认知障碍和神经行为障碍无任何影像学相关性。虽然 DWI 已被用于足月新生儿识别弥散受限的缺血区域，但它也可用于通过表观弥散系数（ADC）来描述早产儿的脑发育，并可能有助于检测导致非运动障碍的异常。最近的数据表明，在没有局灶性病变的婴儿中，WM 中较高的 ADC 值与 2 岁时神经发育评估较差相关。DTI 还可以检测到分数各向异性（FA），它可用于测量微观结构。DTI 还可用于对不成熟大脑中的 WM 束进行成像，并可用于了解大脑的正常发育或对损伤的反应。早产儿大脑中的一些 WM 区域 FA 值较低，这表明即使没有局灶性病变，早产儿的 WM 异常也很广泛。发育中大脑的复杂性可以通过新的束路径成像来解释，它可以评估不同 WM 区域的连通性以及结构与功能之间的关系，例如视辐射的微观结构和视觉评估分数。新生儿脑成像技术的进步为理解起源于早期结构脑组织和成熟的发育中脑的神经行为障碍做出了重大贡献。
