Magnetic resonance imaging of the brain in a cohort of extremely preterm infants.

To define magnetic resonance imaging (MRI) appearances of the brain in extremely preterm infants between birth and term, a sequential cohort of infants born at a gestational age <30 weeks was studied with a dedicated neonatal magnetic resonance scanner. Images of infants (n = 41) with a median gestational age of 27 weeks (range 23 to 29 weeks) were initially obtained at a median age of 2 days (range 1 to 20 days) and then repeatedly studied; 29 (71%) infants had MRI at a median gestational age of 43 weeks (range 38 to 52 weeks) (term MRI). On the initial MRI scan 28 of 41 infants had abnormalities: either intraventricular hemorrhage, germinal layer hemorrhage, ventricular dilatation, or diffuse and excessive high signal intensity in the white matter on T(2)-weighted images. When magnetic resonance images for preterm infants at term gestation were compared with those of infants in the control group born at term, 22 of 29 infants had dilatation of the lateral ventricles, 24 of 29 had squaring of the anterior or posterior horns of the lateral ventricles, 11 of 29 had a widened interhemispheric fissure or extracerebral space, and 22 of 29 had diffuse and excessive high signal intensity in the white matter. There were no cases of cystic periventricular leukomalacia. We conclude that MRI abnormalities are commonly seen in the brain of preterm infants on whom images are obtained within 48 hours of birth and that further abnormalities develop between birth and term. A characteristic appearance of diffuse and excessive high signal intensity in the white matter on T(2)-weighted images is associated with the development of cerebral atrophy and may be a sign of white matter disease. These MRI appearances may help account for the high incidence of neurodevelopmental impairment in extremely preterm infants.     

High-field diffusion tensor imaging characterization of cerebral white matter injury in lipopolysaccharide-exposed fetal sheep

Background:In gyrencephalic species such as sheep, precise anatomical and microstructural characterization of the consequences of fetal inflammation remains scarce. The goal of this study was to characterize changes in white matter (WM) structure using advanced magnetic resonance imaging (MRI) following lipopolysaccharide (LPS) exposure in the preterm-equivalent fetal sheep.Methods:Preterm (0.7 gestation) fetal sheep received vehicle (Sham group) or LPS (LPS group), and fetal brains were collected 10 d later for subsequent ex vivo MRI. T(1)-weighted (T(1)W), T(2)-weighted (T(2)W), and diffusion tensor imaging (DTI) data were collected.Results:Fetuses exposed to LPS exhibited reductions in WM volume and corpus callosum thickness at 10 d recovery. Characteristic patterns of diffuse and focal WM lesions (necrosis or cysts) could be identified by various T(1), T(2), and DTI signal changes.Conclusion:Fetal LPS exposure induces a pattern of injury characterized by diffuse and focal WM injury that closely reproduces that observed clinically in preterm infants. This work provides anatomical and microstructural MRI assessment, as well as histopathological correlates, of the consequences of LPS exposure in an animal model with a WM structure similar to that of the human brain. This work will help to further our understanding of MRI changes in preterm infants.     

Diffusion tensor imaging of the inferior colliculus and brainstem auditory-evoked potentials in preterm infants

Background  Preterm and low-birth-weight infants have an increased risk of sensorineural hearing loss. Brainstem auditory-evoked potentials (BAEP) are an effective method to detect subtle deficits in impulse conduction in the auditory pathway. Abnormalities on diffusion tensor imaging (DTI) have been shown to be associated with perinatal white-matter injury and reduced fractional anisotropy (FA) has been reported in patients with sensorineural hearing loss. Objectives  To evaluate the possibility of a correlation between BAEP and DTI of the inferior colliculus in preterm infants. Materials and methods  DTI at term age and BAEP measurements were performed on all very-low-birth-weight or very preterm study infants (n=56). FA and apparent diffusion coefficient (ADC) of the inferior colliculus were measured from the DTI. Results  Shorter BAEP wave I, III, and V latencies and I–III and I–V intervals and higher wave V amplitude correlated with higher FA of the inferior colliculus. Conclusion:  The association between the DTI findings of the inferior colliculus and BAEP responses suggests that DTI can be used to assess the integrity of the auditory pathway in preterm infants.     

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。     

Correlation among Magnetic Resonance Imaging Parameters of Brain in Preterm Neonates at Term Equivalent Age

Objectives

To assess the spectrum of Magnetic Resonance Imaging (MRI) abnormalities among preterm babies at term equivalent age using objective scoring and to study the association among MRI variables.

Methods

Ninety-four preterm babies born at ≤32 wk of gestation and / or birth weight ≤ 1500 g at term equivalent age who underwent cranial MRI between April 2011 and August 2012 and the MRI interpreted by experienced radiologists were studied. In 2014, the MRI was retrospectively re-interpreted by the same radiologists using an objective scoring system described by Kidokoro. Spectrum of MRI abnormalities, their association with perinatal variables and correlation among white matter (WM), grey matter and cerebellar scores were analyzed.

Results

MRI abnormalities observed were WM signal abnormality (24 %), lateral ventricular dilatation (16 %), WM cystic abnormality (13 %), deep grey matter signal abnormality (9 %), cerebellar volume reduction (9 %) and deep grey matter volume reduction (8 %). Sepsis was significantly associated with occurrence of WM and cerebellar abnormalities (p < 0.05). WM scores did not show significant correlation with cortical grey matter and deep grey matter scores while cerebellar scores showed a weak positive correlation with WM (r = 0.33), cortical grey matter (r = 0.27) and deep grey matter scores (r = 0.22).

Conclusions

MRI abnormalities are common in preterm infants, with 60 % showing some abnormality at term equivalent age. Among perinatal characteristics, sepsis was identified as risk factor for WM and cerebellar injury. Grey matter abnormality occurs independent of WM abnormality. Cerebellar abnormalities appear to coexist with either WM or grey matter changes.

     

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.     

Fractional anisotropy in white matter tracts of very-low-birth-weight infants

Background Advances in neonatal intensive care have not yet reduced the high incidence of neurodevelopmental disability among very-low-birth-weight (VLBW) infants. As neurological deficits are related to white-matter injury, early detection is important. Diffusion tensor imaging (DTI) could be an excellent tool for assessment of white-matter injury. Objective To provide DTI fractional anisotropy (FA) reference values for white-matter tracts of VLBW infants for clinical use. Materials and methods We retrospectively analysed DTI images of 28 VLBW infants (26–32 weeks gestational age) without evidence of white-matter abnormalities on conventional MRI sequences, and normal developmental outcome (assessed at age 1–3 years). For DTI an echoplanar sequence with diffusion gradient (b = 1,000 s/mm²) applied in 25 non-collinear directions was used. We measured FA and apparent diffusion coefficient (ADC) of different white-matter tracts in the first 4 days of life. Results A statistically significant correlation was found between gestational age and FA of the posterior limb of the internal capsule in VLBW infants (r = 0.495, P<0.01). Conclusion Values of FA and ADC were measured in white-matter tracts of VLBW infants. FA of the pyramidal tracts measured in the first few days after birth is related to gestational age.     

Late‐onset bloodstream infections in preterm infants: A 2‐year survey

Background: We determined the prevalence and risk factors for late‐onset bloodstream infections (LO‐BSI), the distribution of pathogens and the outcomes of affected preterm infants. Methods: The records of all preterm infants (<37 weeks gestation) born between 2004 and 2005 and hospitalized in the neonatal intensive care unit for >3 days were retrieved for this retrospective matched case–control study. Results: A total of 108 out of 1459 preterm infants (7.4%) had 142 episodes of LO‐BSI. The highest LO‐BSI rate (44%) was among 198 very‐low‐birthweight infants (<1500 g). The most common causative organisms were Coagulase‐negative staphylococci and Klebsiella (60% and 13%, respectively). The mean hospital stay was 64 days for LO‐BSI preterm infants versus 48 days for non‐LO‐BSI preterm infants. Congenital malformations and peripheral catheters were independent risk factors for LO‐BSI. Crude mortality rates were 6.9% (LO‐BSI) and 3.0% (non‐LO‐BSI), with an LO‐BSI‐attributable mortality of 3.9%. Conclusion: LO‐BSI frequently affect very‐low‐birthweight infants. Strategies to prevent LO‐BSI should target peripheral catheters.     

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。     

Serial brain MRI and ultrasound findings: relation to gestational age, bilirubin level, neonatal neurologic status and neurodevelopmental outcome in infants at risk of kernicterus

Aims

To describe cranial ultrasound (cUS) and magnetic resonance imaging (MRI) findings in neonates at risk of kernicterus, in relation to gestational age (GA), total serum bilirubin (TSB), age at imaging and neurodevelopmental outcome.

Patients and methods

Neonates with peak TSB > 400 μmol/L and/or signs of bilirubin encephalopathy. Review of neonatal data, cUS, preterm, term and later MRI scans and neurodevelopmental outcome.

Results

11 infants were studied, two < 31, four 34-36 and five 37-40 weeks GA. TSB levels: 235-583 μmol/L (preterms); 423-720 μmol/L (terms). Neonatal neurological examination was abnormal in 8/10. cUS showed increased basal ganglia (BG) in 4/9 infants and white matter (WM) echogenicity, lenticulostriate vasculopathy (LSV) and caudothalamic hyperechogencity/cysts (GLCs) in 5/9 infants. MRI showed abnormal signal intensity (SI) in the globus pallidum (GP) in 1/2 preterm, 8/9 term and 9/11 later scans. Abnormal WM SI occurred in 2 preterm, 7 term and 10/11 later scans. Seven infants developed athetoid/dystonic cerebral palsy (CP) and 6 hearing loss (HL). Adverse outcome was associated with abnormal BG on cUS (3/4 CP, 4/4 HL), with high SI in GP (7/9 CP, 6/9 HL) on late T2-weighted MRI (all GA) and on T1/T2-weighted term MRI, mainly in term-born infants. WM abnormalities, GLCs and LSV did not correlate with outcome.

Conclusions

Severe CP occurred with relatively low TSB levels in preterms but only at high levels in full-terms; HL was difficult to predict. Early scans did not reliably predict motor deficits whilst all children with CP had abnormal central grey matter on later scans. Abnormal WM was seen early suggesting primary involvement rather than change secondary to grey matter damage. Why characteristic central grey matter MRI features of kernicterus are not seen early remains unexplained.     

Changes in care and short-term outcome for very preterm infants in Estonia

Aim: To identify recent changes in short‐term outcome and care for very preterm infants in Estonia. Methods: Comparison of two population‐based cohorts of very preterm infants born alive at 22–31 gestational weeks. In 2007–2008, data were recorded prospectively in a neonatal register. For the cohort born in 2002–2003, the same variables were extracted retrospectively from the hospital records. Infants were followed up to discharge or death. Results: The cohort of 2007−2008 contained a higher proportion of infants born by caesarean section and of infants who received antenatal corticosteroids, maternal antibiotics, or surfactant therapy than the earlier cohort. A higher proportion of infants was admitted for care in 2007–2008 (98% vs. 94%; p = 0.013). During the study period, survival until discharge increased (85% vs. 78%; p = 0.041), although the length of hospital stay was unchanged. The use of mechanical ventilation, inotropes, and postnatal antibiotics decreased. Neonatal morbidity remained unchanged, except for a decrease in severe periventricular/intraventricular hemorrhage. Conclusion: The outcome for very preterm infants in Estonia has improved since 2002. With proactive perinatal management and less invasive neonatal care, survival until discharge increased without concomitant increases in neonatal morbidity and the length of hospital stay.     

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。     

应用弥散张量成像评价支气管肺发育不良早产儿脑白质发育的研究

目的 应用磁共振弥散张量成像（DTI）的各项异性分数（FA）和表观弥散系数（ADC）评价支气管肺发育不良（BPD）早产儿的脑白质发育。方法 以2016年8月至2019年4月生后24 h内收住NICU的出生胎龄≤32周、出生体重<1 500 g,且出院前完成头颅MRI及DTI检查的96例早产儿为研究对象。根据出院诊断分为BPD组（n=48）和非BPD组（n=48）,比较两组DTI相同感兴趣区的FA值和ADC值。结果 两组早产儿脑室周围-脑室内出血、脑室周围白质软化、局灶性脑白质损伤等发生率差异无统计学意义（P > 0.05）。BPD组早产儿内囊后肢、胼胝体压部、枕叶白质、小脑、大脑脚的FA值低于非BPD组（P < 0.05）,各ADC值高于非BPD组（P < 0.05）。与非BPD组相比,BPD组早产儿呼吸暂停次数更多、肺炎发生率和机械通气比例更高、辅助通气时间更长（P < 0.05）。结论 BPD对早产儿脑白质发育具有潜在影响,可导致脑白质发育延迟,因此,需关注该类患儿的神经功能。     

Neonatal MRI in preterm infants with periventricular leukomalacia and mild disability

Background: The aim of the present study was to describe the neonatal magnetic resonance imaging (MRI) findings of preterm infants with periventricular leukomalacia and mild neurological disability. Methods: MRI findings at term equivalent were retrospectively investigated in eight preterm infants with mild disability and periventricular leukomalacia diagnosed on MRI in infancy. Results: Linear, spotted, or macular areas of hyperintensity on T1‐weighted imaging and hypointensity on T2‐weighted imaging were identified in all subjects in the white matter lateral to the body of the lateral ventricle. No cystic lesions were seen. These findings were more widespread and more clearly visualized on T2‐weighted imaging than T1‐weighted imaging. Conclusions: Linear, spotted, or macular lesions that are hyperintense on T1‐weighted imaging and hypointense on T2‐weighted imaging are possibly compatible with periventricular leukomalacia.     

Cerebral MRI of very low birth weight children at 6 years of age compared with the findings at 1 year

Background. We have previously reported the results of cerebral MRI examinations in an unselected year cohort of very low birth weight (VLBW) infants at one year of corrected age. Twenty-one (78 %) of 27 infants had abnormal myelination, mainly in the central occipital white matter (COWM) and in the centrum semiovale (CS), seen on T2-weighted images. Twelve infants had irregular and dilated lateral ventricles. We speculated whether these findings indicated perinatal periventricular leukomalacia (PVL). Only two infants had completely normal MRI at age 1 year. Objective. To determine whether the abnormal myelination seen at 1 year of age, was still present, either as delayed myelination or as gliosis caused by perinatal PVL. Materials and methods. In the present study, we report the results of follow-up cerebral MRI in 20 of these infants at 6 years of age. Results. Most of the children with MRI deviations at 1 year still had abnormalities at 6 years. Abnormal myelination in the central occipital white matter combined with abnormalities in the CS or with ventricular dilatation at age 1 year, presented as gliosis in 12 of 13 children at 6 years of age. Abnormalities solely in the COWM at age 1 year had normalised in two of five children and persisted as delayed myelination in three at age 6 years. Gliotic changes in periventricular white matter were found in 12 of 20 children (60 %). Areas most affected were the CS (11 children) and the COWM (9 children). Delayed myelination in COWM was found in six children (30 %), combined with gliosis in CS in three children. Twelve infants had ventricular dilatation both at 1 and 6 years of age. Conclusions. The MRI correlates of PVL, i. e. gliosis and ventricular dilatation, are common findings on cerebral MRI at 6 years of age in VLBW infants. Received: 20 February 1997 Accepted: 1 December 1997     

Early prediction of neurological outcome by term neurological examination and cranial ultrasound in very preterm infants

Aim: To assess the value of term neurological examination and cranial ultrasound in the early prediction of neurological outcome at 12 months corrected age in a cohort of very preterm infants.
Methods: A cohort of 102 preterm infants born at <32 weeks gestation or with a birth weight of <1500 g were assessed using the Hammersmith Term Neurological Examination. They underwent cranial ultrasound examinations according to local guidelines. The Hammersmith Infant Neurological Examination was performed at 12 months corrected age. Scores for the term examinations were compared with scores derived from healthy infants born at term and with scores from low-risk preterm infants at term equivalent age. Term neurological scores and cranial ultrasound findings were compared in the prediction of 12-month neurological outcome.
Results: Seventy-eight (76.5%) preterm infants had suboptimal total neurological scores at term when compared to healthy infants born at term. However, most went on to have optimal neurological scores at 12 months corrected age. When our cohort was compared with low-risk preterm infants at term equivalent age only 14 (13.7%) scored outside the normal range. Neither system of scoring predicted neurological outcome at 12 months corrected age as reliably as cranial ultrasound (sensitivity 0.83, specificity 0.87).
Conclusion: Neurological examination of preterm babies at term may be unreliable in the prediction of neurological outcome at 12 months corrected age. For early prediction of neurological outcome cranial ultrasound examination was found to be more reliable.     

晚期早产儿脑白质损伤临床特点及磁共振影像学发现

目的：探讨晚期早产儿脑白质损伤的临床特点及常规磁共振成像（MRI）和弥散加权成像（DWI）影像学特征。方法：总结2005年1月至2008年5月中国医科大学盛京医院收治的519例早产儿资料（277例晚期早产儿,242例早期早产儿）,对其头部常规MRI和DWI特征进行分析。结果：晚期早产儿中,脑白质损伤118例,占脑损伤的71.9%（118/164）,占全部晚期早产儿的42.6%（118/277）。早期早产儿脑白质损伤占脑损伤的69.2%（92/133）,占全部早期早产儿的38.0%（92/242）,晚期早产儿脑白质损伤发生率与早期早产儿相比无明显差异。晚期早产儿脑白质损伤中无明显临床症状者占61.9%（73/118）,重症脑损伤（广泛性及弥漫性脑损伤）早期有明显临床症状者占75%（15/20）。损伤1周内,DWI表现为高信号,T1WI信号正常或稍高信号,伴或不伴T2WI高信号;弥漫性损伤者呈DWI高信号,常规MRI无明显信号改变。结论：脑白质损伤在晚期早产儿亦较常见。重症脑白质损伤患儿早期多有明显的临床表现。DWI在损伤早期的敏感度高于常规MRI。［中国当代儿科杂志,2010,12（5）：321-326］     

Neurodevelopmental impairment in preterm infants with late-onset infection: not only in extremely preterm infants

Late-onset infection is known to increase the risk of neurodevelopmental impairment in infants born extremely preterm. However, little data is available regarding infants born moderately preterm. The aim of this study was to determine whether late-onset infection in moderately preterm infants (<35 weeks of gestation) was associated with a non-optimal neurodevelopmental outcome at 2 years of age. We analyzed a regional, population-based cohort of infants (LIFT cohort) between January 2003 and December 2009, and we used a propensity score method to reduce bias. Among the 4,618 preterm infants assessed at 2 years, 618 had acquired late-onset infection (13.4 %), and 764 had a non-optimal outcome (16.5 %). The rate of non-optimal outcomes was significantly higher in preterm infants with late-onset infection, irrespective of subgroups of gestational age and birth weight Z-score. After adjusting for the propensity score, the relationship between late-onset infection and non-optimal neurodevelopmental outcome at 2 years among infants born before 35 weeks of gestation remained significant (aOR?=?1.3; 95 % CI 1.01–1.7; p?=?.04). Conclusion: Late-onset infection is associated with poor neurological outcome at 2 years of age among infants born moderately preterm before and after adjustment for the propensity score.