Magnetic resonance imaging at term and neuromotor outcome in preterm infants

In order to evaluate the value of neonatal brain magnetic resonance imaging (MRI) for predicting neuromotor outcome in very low birthweight (VLBW) preterm infants, 51 such infants with gestational age <34 wk underwent brain MRI at term age. Myelination, parenchymal lesions (haemorrhage, leukomalacia, infarction, reduction of white matter), parenchymal lesions without subependymal haemorrhage, ventricular/brain ratios and widths of the extracerebral spaces were assessed. The MRI findings were compared with cranial ultrasound (US) performed at term. Infants' neuromotor development was followed up until 18 mo corrected age. Parenchymal lesions seen in MRI at term predicted cerebral palsy (CP) with 100% sensitivity and 79% specificity, the corresponding figures for US being 67% and 85%, respectively.
Parenchymal lesions in MRI, excluding subependymal haemorrhages, predicted CP with a sensitivity of 82% and a specificity of 97%, the corresponding figures for US being 58% and 100%, respectively. Delayed myelination, ventricular/brain ratios and widths of the extracerebral spaces failed to predict CP. Term age is a good time for neuroradiological examinations in prematurely born high-risk infants. Parenchymal lesions seen in MRI are reliable predictors for CP.     

Neurodevelopmental status at 1 year predicts neuropsychiatric outcome at 14-15 years of age in very preterm infants

BACKGROUND: Neurodevelopmental and behavioural problems have been repeatedly reported in very preterm survivors, often showing themselves later in childhood as poor school performance. Early identification of problems would mean that appropriate remedial therapy can be implemented. We have previously shown that neurodevelopmental status at 1 year was predictive of outcome at 8 years in a cohort of preterm infants. The aim of this paper was to see if neurodevelopmental outcome in adolescence could be predicted by assessment by 1 year in the same cohort of preterm infants. STUDY DESIGN: Prospective cohort study. SUBJECTS: 150 adolescents, born before 33 weeks gestation. OUTCOME MEASURES: Neurological examination, developmental quotient, vision and hearing by 1 year. At 14-15 years, neurological examination, school performance questionnaire, Schonnell test of reading age, a premorbid adjustment score, Rutter behavioural score and for those born from 1981, cognitive tests (WISC-R). RESULTS: A highly significant relationship existed between neurological status by 1 year and the need for extra educational provision, overall neurodevelopmental status, cognitive function in those that had their IQs measured and premorbid adjustment score of prepsychotic symptoms in adolescence. However, status at 1 year was not predictive of adolescent reading age or behavioural score. CONCLUSIONS: Neurodevelopmental assessment at 1 year is predictive of school performance and outcome in the adolescent period.     

Limitations of ultrasonography for diagnosing white matter damage in preterm infants

OBJECTIVES: To compare the accuracy of ultrasonography (US) and magnetic resonance imaging (MRI) in diagnosing white matter abnormalities in preterm infants and to determine the specific indications for MRI. DESIGN: Prospective cohort study. SETTING: A neonatal intensive care unit in France. PATIENTS: All preterm infants (相似文献   

Neuroimaging biomarkers of preterm brain injury: toward developing the preterm connectome

For typically developing infants, the last trimester of fetal development extending into the first post-natal months is a period of rapid brain development. Infants who are born premature face significant risk of brain injury (e.g., intraventricular or germinal matrix hemorrhage and periventricular leukomalacia) from complications in the perinatal period and also potential long-term neurodevelopmental disabilities because these early injuries can interrupt normal brain maturation. Neuroimaging has played an important role in the diagnosis and management of the preterm infant. Both cranial US and conventional MRI techniques are useful in diagnostic and prognostic evaluation of preterm brain development and injury. Cranial US is highly sensitive for intraventricular hemorrhage (IVH) and provides prognostic information regarding cerebral palsy. Data are limited regarding the utility of MRI as a routine screening instrument for brain injury for all preterm infants. However, MRI might provide diagnostic or prognostic information regarding PVL and other types of preterm brain injury in the setting of specific clinical indications and risk factors. Further development of advanced MR techniques like volumetric MR imaging, diffusion tensor imaging, metabolic imaging (MR spectroscopy) and functional connectivity are necessary to provide additional insight into the molecular, cellular and systems processes that underlie brain development and outcome in the preterm infant. The adult concept of the "connectome" is also relevant in understanding brain networks that underlie the preterm brain. Knowledge of the preterm connectome will provide a framework for understanding preterm brain function and dysfunction, and potentially even a roadmap for brain plasticity. By combining conventional imaging techniques with more advanced techniques, neuroimaging findings will likely be used not only as diagnostic and prognostic tools, but also as biomarkers for long-term neurodevelopmental outcomes, instruments to assess the efficacy of neuroprotective agents and maneuvers in the NICU, and as screening instruments to appropriately select infants for longitudinal developmental interventions.     

Early alteration of structural and functional brain development in premature infants born with intrauterine growth restriction

Placental insufficiency with fetal intrauterine growth restriction (IUGR) is an important cause of perinatal mortality and morbidity and is subsequently associated with significant neurodevelopmental impairment in cognitive function, attention capacity, and school performance. The underlying biologic cause for this association is unclear. Twenty-eight preterm infants (gestational age 32.5 +/- 1.9 wk) were studied by early and term magnetic resonance imaging (MRI). An advanced quantitative volumetric three-dimensional MRI technique was used to measure brain tissue volumes in 14 premature infants with placental insufficiency, defined by abnormal antenatal Doppler measurements and mean birth weights <10(th) percentile (1246 +/- 299 g) (IUGR) and in 14 preterm infants matched for gestational age with normal mean birth weights 1843 +/- 246 g (control). Functional outcome was measured at term in all infants by a specialized assessment scale of preterm infant behavior. Premature infants with IUGR had a significant reduction in intracranial volume (mean +/- SD: 253.7 +/- 29.9 versus 300.5 +/- 43.5 mL, p < 0.01) and in cerebral cortical gray matter (mean +/- SD: 77.2 +/- 16.3 versus 106.8 +/- 24.6 mL, p < 0.01) when measured within the first 2 wk of life compared with control premature infants. These findings persisted at term with intracranial volume (mean +/- SD: 429.3 +/- 47.9 versus 475.9 +/- 53.4 mL, p < 0.05) and cerebral cortical gray matter (mean +/- SD: 149.3 +/- 29.2 versus 189 +/- 34.2 mL, p < 0.01). Behavioral assessment at term showed a significantly less mature score in the subsystem of attention-interaction availability in IUGR infants (p < 0.01). Cerebral cortical gray matter volume at term correlated with attention-interaction capacity measured at term (r = 0.45, p < 0.05). These results suggest that placental insufficiency with IUGR have specific structural and functional consequences on cerebral cortical brain development. These findings may provide insight into the structural-functional correlate for the developmental deficits associated with IUGR.     

Cranial magnetic resonance imaging and school performance in very low birth weight infants in adolescence.

AIM: To determine whether neurological deficits are associated with structural anomalies of the brain in very low birthweight (VLBW) infants with subsequent learning disorders but without cerebral palsy, or whether other factors, such as poor early growth, are responsible. METHODS: Eighty seven VLBW infants and eight term controls who had been examined at school between the ages of 12 and 13 years, had cranial magnetic resonance imaging (MRI) scans at 15-17 years of age. RESULTS: Thirty seven (42.5%) of the VLBW children had abnormalities reported on their scans (two porencephaly, 28 periventricular leucomalacia, 24 ventricular dilatation, and 15 thinning of the corpus callosum). No significant differences in intelligence quotient, motor clumsiness, or frequency of attention deficit / hyperactivity disorder were observed between those children with MRI lesions and those with normal scans. Quantitative measurements showed the VLBW infants had smaller brains, and a relatively smaller corpus callosum compared with controls. No association between brain measurements and school performance was observed among the VLBW infants. CONCLUSIONS: The difficulties experienced by VLBW children at school are unlikely to be the result of perinatal brain injury, but they might to be attributable to the effects of poor postnatal growth.     

Feasibility of cerebral MRI in non-sedated preterm-born infants at term-equivalent age: report of a single centre

Aim: MRI is gaining in importance as an imaging tool for brain development and injury in preterm infants. The aim of this study was to evaluate the feasibility of performing MRI in non‐sedated preterm‐born infants at term‐equivalent age (TEA). Methods: A total of 89 infants born before 32 gestational weeks were recruited. Infants were scanned without sedation. Duration of the entire examination including scan repetition and interruptions was registered. Results: Of the 89 infants, 56 (63%) underwent MRI at TEA. Out‐patients required a significantly shorter total MR examination time than did in‐patients (32 ± 12 vs. 54 ± 10 min, p < 0.01). Of the 56 infants, 39 (69.6%) were examined without interruption. Only four (7.2%) of the 56 scans were unusable because of motion artefacts. Mean duration of all scans was 36 ± 14 min. In cases with no interruptions, sessions were completed within 32 ± 12 min; MR sessions with interruption lasted 45 ± 13 min. Conclusion: A well‐trained team is indispensable in obtaining best‐quality images as a prerequisite for good counselling. From our experience, we worked out a guideline to ensure that scans in stable non‐sedated preterm‐born infants at TEA run smoothly and provide high‐quality images.     

Impact of cerebral palsy in patients discharged from neonatal intensive care units

AIM: The aim of this study was to assess the impact and the peculiarities of cerebral palsy (CP) in children discharged from our neonatal intensive care unit (NICU) from January 1998 to April 2004. METHODS: A total of 2 303 children were discharged from our NICU during this period and 1 912 were followed up for 1 year through neurological examination (traditional, Brazelton, general movements) and cranial ultrasound (US); high-risk newborns were evaluated with brain magnetic resonance imaging (MRI) too. RESULTS: In 65 children (3.4% of the follow-up group) were diagnosed CP, and classified as follows: 21 (32%) diplegia, 19 (29%) quadriplegia, 20 (31%) hemiplegia, 4 (6%) double hemiplegia, 1 (2%) dyskinetic form. In diplegia and quadriplegia prevailed low birth weight infants (less than or equal to 2,500 g) and preterm infants, while in hemiplegia prevailed normal birthweight infants (greater than 2,500 g) and infants at term. The main MRI findings were: in diplegia 82% periventricular white matter lesions; in quadriplegia 94% periventricular and/or subcortical white matter lesions; in hemiplegia 95% bilateral periventricular or subcortical white matter lesions, predominating on contralateral cerebral hemisphere; in double hemiplegia 100% periventricular and/or subcortical white matter lesions, 100% enlargement of subarachnoid spaces; in dyskinetic form 100% basal ganglia lesions. CONCLUSIONS: The impact of CP in children discharged from our NICU, in agreement with the literature, is higher than in the total population of newborns, thus it is very important to evaluate carefully high-risk newborns during hospitalization and follow-up, through neurological examination and radiologic imaging (US, MRI), for an accurate and early treatment.     

Safety of magnetic resonance imaging in preterm infants

Aim: As we progress in our knowledge of preterm brain injury, cohort studies are focusing in neuroimaging preterm infants in the first days of life. Magnetic resonance (MR) is the most powerful neuroimaging modality and valuable in understanding perinatal brain injury. The main purpose of the study is to evaluate the safety of MR imaging in very low birth weight (VLBW) infants at our hospital settings where the scanner is located at some distance from the neonatal intensive care unit (NICU). Subjects and methods: This is a prospective study of 33 VLBW infants who underwent early MR imaging (MRI), within 10 days after birth and term corrected age MRI. The study period included June to December 2008. Results: A total of 46 MRI were performed on 33 preterm infants. The mean total time the infants stayed in the bore of the magnet was 13.04 min. No incidences occurred during transfer or during the scans, and no significant changes were found in heart rate, oxygen saturation and temperature. Conclusions: At our hospital settings, the process of transport and MR imaging have been proven to be safe and not to disturb any of the variables measured. MRI should not be restricted to centres with neonatal MR system or MR‐compatible incubator, as long as the process is coordinated and supervised by a multidisciplinary team.     

Postnatal clinical and imaging follow-up of infants with prenatal isolated mild ventriculomegaly: a series of 101 cases

Background Postnatal imaging and clinical outcome of fetuses with isolated mild ventriculomegaly (IMV) have never been systematically analysed. Objective To evaluate the postnatal clinical outcomes of a large cohort of fetuses with IMV and to correlate them with pre- and postnatal imaging. Materials and methods We report a prospective study of 101 fetuses with IMV (10–15 mm ventriculomegaly with otherwise normal US, MRI, karyotype and TORCH screening). IMV was divided into minor (10–11.9 mm) and moderate (12–15 mm) ventriculomegaly. Ventriculomegaly was considered uni- or bilateral, stable, progressive, regressive or resolved according to the prenatal US follow-up. Clinical follow-up was performed by a neuropaediatrician. Postnatal imaging included cranial US (n = 71) and MRI (n = 76). Results The outcome of minor and moderate IMV was excellent in 94% and 85% of infants, respectively. It was not different between uni- and bilateral IMV, and between stable, regressive and resolved IMV, and was independent of gestational age at diagnosis and gender. Fixed neurological abnormalities were observed in nine infants. Postnatal MRI showed white-matter abnormalities in 14 infants, including 6 of the 9 infants with a poor outcome. Conclusion The prognosis was slightly better in minor IMV than in moderate IMV. Postnatal MRI showed white-matter abnormalities in two-thirds of the infants with a poor outcome.     

MRI和DTI评价早产儿脑白质髓鞘发育

目的 应用磁共振(MRI)、磁共振弥散张量成像(DTI)研究早产儿脑白质髓鞘发育的特点。方法 胎龄≤32周、出生体重<1 500 g的31例早产儿根据头部MRI检查分为早产脑损伤组(12例)和早产无脑损伤组(19例)。选取24例足月儿作为对照组。均于胎龄或纠正胎龄37~40周之间完成头部MRI及DTI检查。测定3组相同感兴趣区的部分各向异性参数(FA)和表观扩散系数(ADC)。结果 早产脑损伤组内囊后肢FA值小于早产无脑损伤组和足月对照组 (P < 0.05);早产脑损伤组和早产无脑损伤组的额叶白质和豆状核的FA值小于足月对照组 (P < 0.05);3组间枕叶白质的FA值差异无显著性 (P > 0.05)。早产脑损伤组和早产无脑损伤组内囊后肢、豆状核、枕叶白质、额叶白质的ADC值高于足月对照组 (P < 0.05)。结论 早产儿脑损伤容易出现内囊后肢深部脑白质髓鞘化障碍或延迟。早产儿至纠正胎龄足月时,无论有无脑损伤,脑周围白质及灰质成熟度均低于足月儿。     

新生儿颅脑磁共振检查临床实践的专家共识

颅脑磁共振成像（magnetic resonance imaging,MRI）技术的迅速发展为新生儿脑发育评估、脑损伤诊断和预后判断提供了客观依据,临床应用日益广泛。中国医师协会新生儿科医师分会基于国内外现有研究证据,结合临床实践经验,为新生儿颅脑MRI的适应证和临床实践规范制定专家共识,主要内容包括：（1）疑似新生儿缺氧缺血性脑病、颅内感染、脑卒中,以及原因不明惊厥者应行颅脑MRI;颅脑MRI不纳入早产儿常规脑损伤筛查管理,当颅脑超声筛查有明确损伤证据时应行颅脑MRI进一步评估;对于颅脑超声未见异常的超早产儿和超低出生体重儿,建议在纠正胎龄足月时行颅脑MRI;（2）新生儿颅脑MRI应尽量在非镇静状态下完成;（3）过程中需密切监测生命体征,优化检查条件,保障安全,危重患儿检查需严格评估检查的必要性,可应用磁共振兼容的转运培养箱和呼吸机;（4）目前新生儿颅脑MRI检查可选1.5 T或3.0 T设备,应用新生儿颅脑专用线圈以提高信噪比;常规扫描序列选择应遵循：至少包含轴位T1加权像、轴位T2加权像、弥散加权成像,以及矢状位T1加权像或T2加权像;（5）建议采用结构化或分级报告系统,通过双人审签报告、多中心协作等方式提高报告可靠性。     

Brain imaging findings in very preterm infants throughout the neonatal period: Part II. Relation with perinatal clinical data

This study describes the relation between frequent and clinically relevant brain imaging findings in very preterm infants (GA < 32 weeks), assessed with sequential cranial ultrasonography throughout the neonatal period and MRI around term age, and several potential perinatal risk factors.For ultrasound findings during admission the following independent risk factors were identified: male gender for periventricular echodensities and intraventricular haemorrhage, postnatal corticosteroid treatment for cystic white matter lesions, and lower gestational age for post-haemorrhagic ventricular dilatation. For MRI findings around term age, including punctate white matter lesions, ventricular dilatation, decreased cortical complexity, and diffuse and excessive high signal intensity, no independent risk factors were found.In very preterm infants, the risk factors for frequently found changes on cranial ultrasound have largely remained unchanged over the last decades, while no risk factors could be identified for subtle and diffuse white matter injury as seen on MRI around term age.     

Neurological examination combined with brain MRI or cranial US improves prediction of neurological outcome in preterm infants

BackgroundThe predictive value of the combination of neurological examination and brain magnetic resonance imaging (MRI) or cranial ultrasound (cUS) in preterm infants is not known.AimsTo study the prognostic value of the combination of neurological examination and brain MRI at term equivalent age (TEA) or serial neonatal cUS in very preterm infants for neurosensory outcome at 2 years of corrected age.Study designA prospective follow-up study.SubjectsA total of 216 very preterm infants (birth weight 1132 g [SD 331 g]) born in Turku University Hospital, from 2001 to 2006, were included.Outcome measuresThe Dubowitz neurologic examination and brain MRI were done at TEA, and serial cUS examinations were performed until TEA. The Hammersmith Infant Neurological Examination (HINE) and neurosensory impairments (NSI) were assessed at 2 years of corrected age.ResultsOf all infants, 163 (76%) had one or more deviant neurological items at TEA, and 32 (15%) had the HINE total score below the 10th percentile at 2 years of corrected age. A total of 17 (8%) infants had NSI. Neurological examination at TEA improved the negative and positive predictive values of brain MRI for NSI from 99% to 100%, and from 28% to 35%, respectively, and the negative and positive predictive values of cUS from 97% to 100%, and from 61% to 79%, respectively.ConclusionsThe combination of the Dubowitz neurologic examination and the brain MRI at TEA or serial neonatal cUS provides a valuable clinical tool for predicting long-term neurosensory outcome in preterm infants.     

Brainstem size and function at term age in relation to later neurosensory disability in high-risk, preterm infants

The aim of this study was to measure brainstem size on magnetic resonance imaging (MRI) scans of high-risk, preterm infants, to assess brainstem function by brainstem auditory-evoked potentials (BAEP) and to determine the predictive value of these measures for the neurosensory outcome. A total of 51 preterm infants (gestational age <34 wk, birthweight <1500 g) underwent examinations at term age; neuromotor outcome and hearing were followed up until a corrected age of 18 mo. Fourteen (27%) infants had neurosensory disability. Those with a later neurosensory disability had a significantly smaller brain stem than those with a normal outcome. The preterm infants had significantly longer peak latency (L) V and interpeak latency (IPL) III–V than the full-term control infants. Most of the preterm infants with severe cerebral palsy or hearing loss had abnormal BAEP. Sensitivity of morphometric dimensions for predicting neurosensory disability was only 20–31%, but specificity was 97–100%. Abnormal L I and IPL III–V in BAEP predicted disability with a sensitivity of 93% and a specificity of 57–59%.
Conclusion: We conclude that adverse events during the perinatal period may lead to morpho-functional changes in the brain stem in high-risk, preterm infants, and it seems that functional changes are accurate in predicting neurosensory disability in such patients.     

脑性瘫痪儿童的MRI特征

目的 探讨脑性瘫痪(脑瘫)患儿脑MR／的表现及其与出生胎龄和脑瘫类型的关系。方法 回顾性分析104例脑瘫患儿的病史、l临床与MR／表现。结果 早产与足月儿脑瘫类型构成显著不同,早产儿以痉挛性双瘫多见(占66．O％),而足月儿偏瘫和失调型高于早产儿。104例脑瘫患儿MR／异常率为84．7％,早产和足月儿组MHI异常率差异无显著性。痉挛型双瘫、四肢瘫、偏瘫、手足徐动型和失调型脑瘫MR／异常率分别为89．4％、100％、100％、54．5％和90．O％。31／42例痉挛性双瘫表现为脑室周围白质软化症(PVL),而以早产儿双瘫更多见(90％);各类型脑瘫的MR／异常表现不同,双瘫以PVL为主,徐动型表现为基底节病变或．PVL失调型绝大部分存在先天性小脑发育不全,偏瘫型突出表现为单侧脑损伤。出生胎龄与MRI特点有关,早产儿组以PVL为特征,见于除失调型外的其他脑瘫类型;足月儿脑瘫MR／异常表现变化多且病变广泛。结论MR／有助于评价各型脑瘫的病理特点及其与出生胎龄的关系．对脑瘫病因的推测有帮助。     

高危晚期早产儿脑病临床特点及磁共振影像学评估

目的了解高危晚期早产儿(LPI)脑病的危险因素、临床特点及磁共振(MRI)影像学变化。方法对2009年1月至2014年12月住院且存在脑损伤高危因素的LPI,进行头颅MRI检查,分析LPI脑病危险因素、临床特点及头颅MRI特征。结果完成MRI检查的LPI共1 007例,影像学符合早产儿脑病患儿313例(31.1%)。LPI脑病中白质损伤占76.7%。LPI脑病的发生与胎龄无相关性,但随着出生体重增加,脑病检出率逐渐增高(P0.05)。Logistic回归分析结果显示:复苏史是早产儿脑病发生的独立危险因素(P0.01)。结论早产儿脑病在高危LPI中亦较常见,特别是脑白质损伤。复苏病史是LPI脑病的独立危险因素,需引起重视。     

Brain imaging findings in very preterm infants throughout the neonatal period: Part I. Incidences and evolution of lesions, comparison between ultrasound and MRI

This study describes the incidence and evolution of brain imaging findings in very preterm infants (GA < 32 weeks), assessed with sequential cranial ultrasound (cUS) throughout the neonatal period and MRI around term age. The accuracy of both tools is compared for findings obtained around term.Periventricular echodensities and intraventricular haemorrhage were the most frequent cUS findings during admission. Frequent findings on both cUS and MRI around term included ventricular dilatation, widened extracerebral spaces, and decreased cortical complexity. MRI additionally showed punctate white matter lesions and diffuse and excessive high signal intensity, but did not depict lenticulostriate vasculopathy and calcifications, and was less reliable for germinolytic and plexus cysts.cUS detected most abnormalities that have been associated with abnormal neurodevelopmental outcome.     

Brain lesions in preterm infants: initial diagnosis and follow-up

Children surviving premature birth present with a wide spectrum of motor, sensory and cognitive disabilities, ranging from slight motor deficits, school difficulties and behavioural problems to cerebral palsy and mental retardation. The anatomic and functional substrate of these problems can be investigated using a variety of imaging techniques. Cranial US coupled with colour Doppler is a well-established method for the initial diagnosis of intraventricular haemorrhage, parenchymal haemorrhagic infarct and periventricular leukomalacia. MRI is useful for the follow-up study of brain maturation. Conventional T1- and T2-weighted sequences, magnetization transfer and diffusion tensor imaging coupled with sophisticated tools of tissue segmentation and analysis at a voxel level offer substantial anatomic and functional information on pathological conditions that define the prognosis of preterm infants.     

White matter changes in extremely preterm infants,a population‐based diffusion tensor imaging study

Aim: To investigate cerebral white matter (WM) abnormalities (J Pediatr 2003; 143: 171) and diffuse and excessive high signal intensities (DEHSI), (J Pediatr 1999; 135: 351) in a cohort of extremely preterm infants born in Stockholm during a 3‐year period, using magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Methods: MRI at term‐equivalent age was performed in 109 infants and DTI data were acquired in 54 infants. Survival rate in the entire cohort was 67%. Sixteen term‐born healthy control infants were scanned for comparison. Results: No or mild WM abnormalities were seen in 86% of infants and 14% had moderate or severe WM abnormalities. DEHSI were seen in infants with all grades of white matter abnormalities and were present in 56% of infants. In the WM at the level of centrum semiovale, infants with any WM abnormalities or DEHSI had lower Fractional Anisotropy and higher Apparent Diffusion Coefficient compared with control infants. No significant differences in diffusion were seen in infants without DEHSI compared with the controls in this region. Compared with controls, the preterm infants had significantly altered diffusion in the corpus callosum. Conclusion: Only 14% of the extremely preterm infants had moderate or severe WM abnormalities on MRI. However, the incidence of DEHSI was high. In the DEHSI regions, changes in diffusion parameters were detected, indicating altered WM organization.