Diffusion MRI Microstructural Abnormalities at Term-Equivalent Age Are Associated with Neurodevelopmental Outcomes at 3 Years of Age in Very Preterm Infants

BACKGROUND AND PURPOSE:Microstructural white matter abnormalities on DTI using Tract-Based Spatial Statistics at term-equivalent age are associated with cognitive and motor outcomes at 2 years of age or younger. However, neurodevelopmental tests administered at such early time points are insufficiently predictive of mild-moderate motor and cognitive impairment at school age. Our objective was to evaluate the microstructural antecedents of cognitive and motor outcomes at 3 years'' corrected age in a cohort of very preterm infants.MATERIALS AND METHODS:We prospectively recruited 101 very preterm infants (<32 weeks'' gestational age) and performed DTI at term-equivalent age. The Differential Ability Scales, 2nd ed, Verbal and Nonverbal subtests, and the Bayley Scales of Infant and Toddler Development, 3rd ed, Motor subtest, were administered at 3 years of age. We correlated DTI metrics from Tract-Based Spatial Statistics with the Bayley Scales of Infant and Toddler Development, 3rd ed, and the Differential Ability Scales, 2nd ed, scores with correction for multiple comparisons.RESULTS:Of the 101 subjects, 84 had high-quality DTI data, and of these, 69 returned for developmental testing (82%). Their mean (SD) gestational age was 28.4 (2.5) weeks, and birth weight was 1121.4 (394.1) g. DTI metrics were significantly associated with Nonverbal Ability in the corpus callosum, posterior thalamic radiations, fornix, and inferior longitudinal fasciculus and with Motor scores in the corpus callosum, internal and external capsules, posterior thalamic radiations, superior and inferior longitudinal fasciculi, cerebral peduncles, and corticospinal tracts.CONCLUSIONS:We identified widespread microstructural white matter abnormalities in very preterm infants at term that were significantly associated with cognitive and motor development at 3 years'' corrected age.

Premature birth is associated with a significantly increased risk of brain abnormalities and long-term neurodevelopmental impairment. Injuries or maturational delays affecting the WM are observed in 50%–80% of very preterm infants.^1-3 These abnormalities are associated with serious neurodevelopmental impairment.^1,3,4 However, such abnormalities are challenging to detect using conventional MR imaging techniques alone. Fortunately, DTI, a specialized form of MR imaging that can sensitively query the brain''s microstructure, offers a novel approach for identifying these WM injuries. In preterm brains, the evolution of fractional anisotropy (FA) and mean diffusivity (MD), 2 metrics derived from DTI, varies from that of normative populations, and underlying brain injury may lead to neurodevelopmental impairment later in life.^4-6Functional MR imaging with the FMRIB Tract-Based Spatial Statistics (TBSS; http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/TBSS) tool uses observer-independent voxelwise statistical analysis to process the complex information contained within diffusion-weighted images.^4-16 TBSS can be used to identify specific WM tracts and structures in the infant brain that correlate with later developmental outcomes.^8,10,13-15 Previous studies have used TBSS to objectively assess WM microstructure following clinical events such as infection, sports injury, or preterm brain injury (eg, intraventricular hemorrhage) and to relate the associated WM alterations to outcomes.^9,11,16-19 In addition, studies have used TBSS to identify brain regions and tracts in which FA significantly correlates with cognitive and motor outcomes at 2 years of age or younger.^10,13,15 These studies have consistently concluded that higher FA is associated with better motor, cognitive, and language functioning.Past studies emphasizing the value of TBSS correlated DTI parameters with neurodevelopmental outcomes derived from the Bayley Scales of Infant and Toddler Development, 3rd ed (Bayley-III) collected at 2 years of age or younger. Such standardized assessments are administered between 18 and 24 months of age, representing the earliest time point at which cognitive, language, and motor development can be reliably ascertained. However, assessment at these earliest ages is not necessarily predictive of school age outcomes.^20-22 For example, the Bayley-III Motor subscale at 2 years of age significantly underestimates rates of motor impairment at 4 years of age in preterm infants.²² Spencer-Smith et al²³ showed that cognitive delay, as assessed by the Bayley-III administered at 2 years of age, was not strongly associated with cognitive impairment at 4 years of age as assessed by the Differential Ability Scales, 2nd ed (DAS-II).²⁴ We propose that correlating FA from term-equivalent age MR imaging with 3-year outcomes may provide a more robust understanding of the early changes in WM microstructure that are also significantly associated with cognitive development.Our objective was to test the hypothesis that WM microstructure, assessed using TBSS at term-corrected age (CA), is associated with neurodevelopmental performance at 3 years'' CA in a regional cohort of very preterm infants.     

Brain MRI Measurements at a Term-Equivalent Age and Their Relationship to Neurodevelopmental Outcomes

BACKGROUND AND PURPOSE:An increased prevalence of disabilities is being observed as more preterm infants survive. This study was conducted to evaluate correlations between brain MR imaging measurements taken at a term-equivalent age and neurodevelopmental outcome at 2 years'' corrected age among very low–birth-weight infants.MATERIALS AND METHODS:Of the various brain MR imaging measurements obtained at term-equivalent ages, reproducible measurements of the transcerebellar diameter and anteroposterior length of the corpus callosum on sagittal images were compared with neurodevelopmental outcomes evaluated by the Bayley Scales of Infant Development (II) at 2 years'' corrected age (mean ± standard deviation, 16.1 ± 6.4 months of age).RESULTS:Ninety infants were enrolled. The mean gestational age at birth was 27 weeks and the mean birth weight was 805.5 g. A short corpus callosal length was associated with a Mental Developmental Index <70 (P = .047) and high-risk or diagnosed cerebral palsy (P = .049). A small transcerebellar diameter was associated with a Psychomotor Developmental Index <70 (P = .003), Mental Developmental Index <70 (P = .004), and major neurologic disability (P = .006).CONCLUSIONS:A small transcerebellar diameter and short corpus callosal length on brain MR imaging at a term-equivalent age are related to adverse neurodevelopmental outcomes at a corrected age of 2 years and could be a useful adjunctive tool for counseling parents about future developmental outcomes.

The survival rate of preterm infants has increased with the advances in neonatal care in recent decades. However, a higher prevalence of disabilities has also been observed in survivors of preterm birth at infancy and in childhood.^1,2 Factors such as intraventricular hemorrhage,³ hypoxia, prematurity,^3–5 and neonatal care^3,6 have been reported to affect the developing brain; the mechanism of injury during the development of the cerebellum and corpus callosum in surviving premature infants may be caused by primary destruction or underdevelopment⁷ and axonal injury,⁸ respectively. These factors in turn result in an altered brain volume or structure that can be seen as a reduced cerebral and/or cerebellar volume,^3,9,10 subarachnoid space widening,^3,6,11 corpus callosum thinning,^12–14 and posthemorrhagic ventricular dilation on brain MR imaging.¹⁵ These findings have led to reports of various measurements of MR imaging as potential predictors of neurologic outcomes at infancy or in childhood.^10,14,16,17We conducted a study in a single neonatal intensive care unit (NICU) to evaluate correlations between brain MR imaging measurements taken at term-equivalent age and the neurodevelopmental outcomes at 2 years'' corrected age.     

Gestational Age at Birth and Brain White Matter Development in Term-Born Infants and Children

BACKGROUND AND PURPOSE:Studies on infants and children born preterm have shown that adequate gestational length is critical for brain white matter development. Less is known regarding how variations in gestational age at birth in term infants and children affect white matter development, which was evaluated in this study.MATERIALS AND METHODS:Using DTI tract-based spatial statistics methods, we evaluated white matter microstructures in 2 groups of term-born (≥37 weeks of gestation) healthy subjects: 2-week-old infants (n = 44) and 8-year-old children (n = 63). DTI parameters including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated by voxelwise and ROI methods and were correlated with gestational age at birth, with potential confounding factors such as postnatal age and sex controlled.RESULTS:Fractional anisotropy values, which are markers for white matter microstructural integrity, positively correlated (P < .05, corrected) with gestational age at birth in most major white matter tracts/regions for the term infants. Mean diffusivity values, which are measures of water diffusivities in the brain, and axial and radial diffusivity values, which are markers for axonal growth and myelination, respectively, negatively correlated (P < .05, corrected) with gestational age at birth in all major white matter tracts/regions excluding the body and splenium of the corpus callosum for the term infants. No significant correlations with gestational age were observed for any tracts/regions for the term-born 8-year-old children.CONCLUSIONS:Our results indicate that longer gestation during the normal term period is associated with significantly greater infant white matter development (as reflected by higher fractional anisotropy and lower mean diffusivity, axial diffusivity, and radial diffusivity values); however, similar associations were not observable in later childhood.

It is well known that infants born with low gestational age (preterm, <37 completed weeks of gestation) are relatively more vulnerable to brain white matter injury or abnormal white matter development. White matter damage in extremely or very preterm infants (<32 completed weeks of gestation) is common, and increased risk is associated with lower gestational age¹; white matter microstructural differences in moderate or late preterm infants (32–36 completed weeks of gestation) compared with term infants have also been reported.² The abnormality of white matter development associated with low gestational age in preterm infants may extend well beyond infancy, as indicated by observed differences in adolescents born prematurely compared with term-born controls.^3–5 Furthermore, abnormal white matter development associated with preterm birth is also linked to adverse long-term neurodevelopmental outcomes in children at different ages.^6–8The effects of gestational age on neurologic or neurodevelopment for term-born children (≥37 completed weeks of gestation) have not been investigated until recently. Several new studies (most of them population-based) reported positive associations between longer gestational age (excluding postterm, which is ≥42 weeks of gestation) and better cognitive and/or neurodevelopment in term-born children, such as higher scores on Bayley scales of mental and motor development during the first year of life^9,10; more school readiness and cognitive and educational ability at age 3 years¹¹; higher intelligence quotient scores¹² and less vulnerability to low early developmental index at age 6–7 years¹³; greater reading, math, and achievement scores in the third grade¹⁴; and better test scores in elementary and middle school and higher probability of being gifted.¹⁵Brain structural and functional development is directly related with neurodevelopment and cognitive performance in children. However, very few studies have addressed whether length of gestation at term birth is associated with differences in later brain development in children as measured by neuroimaging, particularly for white matter development (a recent study reported associations between longer gestation and higher brain gray matter density measured by MR imaging in term-born healthy 6–10-year-old children¹⁶). In addition, although white matter maturation before and after term has been investigated via imaging studies,¹⁷ there is insufficient quantitative characterization of white matter maturation during the normal term period beyond the common perception that white matter is developing rapidly during this time. In each week of gestation and/or week of life during the term period, white matter continues to mature in patterns of posterior to anterior and central to peripheral.¹⁸ A few studies have evaluated white matter microstructures in relation to term gestational ages^19,20; nevertheless, studies including white matter imaging data for term-born infants have mostly focused on the comparison to preterm,^20,21 but not on the trajectory of white matter development in term-born infants during the normal term period. Nor is it clear whether gestational lengths at birth of term-born infants impact this trajectory and longer-term development into childhood. In this study, DTI measures were used to examine potential associations between gestational age at birth and brain white matter microstructural development in 2 well-characterized cohorts of healthy term-born subjects (2-week old infants and 8-year-old children).     

MR多参数评分鉴别脑胶质瘤术后复发与放射性脑损伤的初步研究

目的 探讨MR多参数评分系统对脑胶质瘤术后复发与放射性脑损伤的诊断价值.资料与方法 对18例脑胶质瘤术后出现异常强化区患者进行扩散加权成像(DWI)、氢质子磁共振波谱(1H-MRS)检查.计算感兴趣区的表观扩散系数比值(rADC)和代谢物峰值比值[胆碱/肌酸(Cho/Cr)、胆碱/氮-乙酰天门冬氨酸(Cho/NAA)].根据受试者工作特征(ROC)曲线确定各比值参数的最佳诊断阈值,并对每个病灶分别进行评分,联合多个参数(rADC、Cho/Cr、Cho/NAA)评分结果建立多参数评分系统,对每个病灶综合评分,总得分≥12者诊断为复发,总得分<2者诊断为放射性脑损伤.通过Kappa检验分析各参数诊断结果与金标准诊断结果的吻合程度.结果 最佳诊断阈值分别为:1.41(rADC)、1.31(Cho/Cr)和1.43(Cho/NAA),诊断准确性、敏感性、特异性分别为:83.3%、83.3%、83.3%(rADC),83.3%、91.7%、66.7%(Cho/Cr),83.3%、83.3%、83.3%(Cho/NAA),多参数评分系统(94.4%、91.7%、100%);诊断结果与金标准吻合程度分别为:rADC(高度,K=0.64)、Cho/NAA(高度,k=0.64)、Cho/Cr(高度,K=0.61)、多参数评分系统(极强,K=0.87).结论 与MR单个参数诊断结果相比,MR多参数评分系统可明显提高对胶质瘤术后复发与放射性脑损伤的诊断准确性.     

Correlation of MRI Brain Injury Findings with Neonatal Clinical Factors in Infants with Congenital Diaphragmatic Hernia

BACKGROUND AND PURPOSE:Infants with congenital diaphragmatic hernia are reported to have evidence of brain MR imaging abnormalities. Our study aimed to identify perinatal clinical factors in infants with congenital diaphragmatic hernia that are associated with evidence of brain injury on MR imaging performed before hospital discharge.MATERIALS AND METHODS:MRIs performed before hospital discharge in infants with congenital diaphragmatic hernia were scored for brain injury by 2 pediatric neuroradiologists. Perinatal variables and clinical variables from the neonatal intensive care unit stay were analyzed for potential associations with brain MR imaging findings.RESULTS:Fifty-three infants with congenital diaphragmatic hernia (31 boys) were included. At least 1 abnormality was seen on MR imaging in 32 infants (60%). The most common MR imaging findings were enlarged extra-axial spaces (36%), intraventricular hemorrhage (23%), ventriculomegaly (19%), white matter injury (17%), and cerebellar hemorrhage (17%). The MR imaging brain injury score was associated with extracorporeal membrane oxygenation (P = .0001), lack of oral feeding at discharge (P = .012), use of inotropes (P = .027), and gastrostomy tube placement before hospital discharge (P = .024). The MR imaging brain injury score was also associated with a large diaphragmatic defect size (P = .011).CONCLUSIONS:Most infants with congenital diaphragmatic hernia have at least 1 abnormality identified on MR imaging of the brain performed before discharge. The main predictors of brain injury in this population are a requirement for extracorporeal membrane oxygenation, large diaphragmatic defect size, and lack of oral feeding at discharge.

Congenital diaphragmatic hernia (CDH), with an incidence of 1 case per 2000 live births, is an anomaly associated with substantial morbidity and mortality.¹ Survivors of CDH are at risk for long-term respiratory, gastrointestinal, nutritional, hearing, and neurologic sequelae, requiring multidisciplinary support, especially during early childhood.¹ Prenatal predictive factors for increased morbidity and mortality include prenatal imaging findings of liver herniation into the chest, lung to head ratio on prenatal sonography, or lung volumes on fetal MR imaging.^2–4 The size of the diaphragmatic defect is another factor that likely plays a major role in morbidity and mortality in infants with congenital diaphragmatic hernia.⁵ However, the association of the defect size with evidence of injury on brain imaging has not been studied, to our knowledge.Long-term neurodevelopmental and neurobehavioral disabilities are reported in up to 70% of infants with congenital diaphragmatic hernia.^6–9 Both brain maturational delays and evidence of brain injury have been reported on imaging.^8,9 There continues to be some controversy about the correlation of neuroimaging abnormalities in CDH with neurologic outcome. In a small cohort of patients with CDH with prenatal and postnatal imaging, Tracy et al⁹ identified an association between brain injury seen on postnatal CT/MR imaging in 4 infants and neurodevelopmental outcome at 1 year. There was no correlation between prenatal factors and neurodevelopmental outcome in this study.⁹ In another study by Danzer et al,¹⁰ postnatal brain MR imaging abnormalities were associated with lower cognitive scores, motor dysfunction, and language deficits.The impact of extracorporeal membrane oxygenation (ECMO) on neonates with CDH requiring ECMO is of clinical relevance. Studies suggest that neonates with CDH who require ECMO have a greater incidence of adverse neurodevelopmental sequelae, though it unclear whether the severity of the illness leading up to ECMO (hypercapnia, hypotension, and so forth) or the ECMO itself should be implicated.^6,11Which clinical factors in the neonatal intensive care unit play a role in brain injury in infants with CDH is yet to be determined.In this study, we have developed a brain injury score to determine whether brain injury seen on predischarge MRI in infants with CDH is associated with diaphragmatic defect size and postnatal clinical factors in the NICU.     

Interobserver Reliability of an MR Imaging Scoring System in Infants with Hypoxic-Ischemic Encephalopathy

BACKGROUND AND PURPOSE:MR imaging has a key role in predicting neurodevelopmental outcomes following neonatal hypoxic-ischemic encephalopathy (HIE). A novel MR imaging scoring system for hypoxic-ischemic brain injury was used in our patient population with the aim of assessing interobserver variability and developing subcategories for the severity of brain injury.MATERIALS AND METHODS:We evaluated brain MR images of 252 infants who underwent hypothermia for HIE between 2014 and 2019. First, 40 infants were selected randomly to test interobserver variability. Discrepancies were identified during the assessment of the first 20 MR images. The remaining 20 MR images were scored after adjusting the scoring system. Second, we determined cutoff values for the severity of injury that were based on the percentiles of the total scores in the full cohort.RESULTS:The interobserver reliability showed excellent agreement for the total score both before (intraclass correlation coefficient = 0.96; 95% CI 0.89–0.99) and after the adjustment (intraclass correlation coefficient = 0.96; 95% CI, 0.89–0.98). The average of the differences and the agreement interval between the 2 readers decreased after the adjustment. Subcategories of brain injury were the following: We considered a total score of ≤4 (≤75%) as normal, 5–10 (76%–90%) as mild, 11–15 (91%–95%) as moderate, and >15 (>95%) as severe brain injury. The agreement on the classification of brain injury improved in the second epoch (weighted κ = 0.723 versus 0.887).CONCLUSIONS:The adjusted scoring system may lead to a higher degree of interrater agreement. The presented cutoff values may be used to determine the severity of brain injury in future clinical studies including infants with mild hypoxia-ischemia.

Hypoxic-ischemic encephalopathy (HIE) occurs in 2–3 per 1000 live term births in developed countries.¹ To date, therapeutic hypothermia (TH) initiated within the first 6 hours of life and continued for 72 hours with a target central temperature of 33.5°C is the only available treatment to reduce the risk of death and neurodevelopmental impairment.^2,3The ability to predict neurodevelopmental outcomes following HIE allows parents and caregivers to optimize care beyond the neonatal period. MR imaging has a key role in predicting neurologic outcomes.^4,5 Although many previously reported MR imaging scoring systems have been related to outcome,^6-8 they were usually performed with conventional sequences. The widely used scoring system of Barkovich et al⁶ published before the hypothermic era did not originally incorporate diffusion-weighted images, even though DWI has been recognized as the most reliable MR imaging sequence to assess injury during the first week after an hypoxic-ischemic event.^4,9 Recently, Weeke et al¹⁰ described a novel and more detailed MR imaging scoring system for term infants with HIE, incorporating DWI and ¹H-MR spectroscopy sequences as well patterns of injury to the gray matter, white matter, and cerebellum to improve the predictive value of MR imaging studies in infants with HIE. The gray matter subscore was an independent predictor of adverse outcome at 2 years of age and at school age.¹⁰Given that our inclusion criteria for infants to undergo TH at Brigham and Women''s Hospital had been broadened, offering cooling to milder cases and infants born at >34 weeks of gestation, we wished to explore the application of this new scoring system in our TH cohort.We applied the new scoring system to our diverse patient population with the aim of assessing the observer variability between 2 experienced readers. We identified discrepancies during the evaluation of the first 20 MR imaging scans and adjusted the scoring system of Weeke et al¹⁰ accordingly.Second, we also aimed to develop subcategories of severity from the scores of normal brain and, mild, moderate, severe brain injury. Our hypothesis was that the adjusted scoring system can improve interobserver reliability and increase the ease and reliability of the application of this scoring system as a new standard in the documentation of cerebral injury in the setting of hypoxic-ischemic encephalopathy.     

实验性癫癎大鼠脑MRI与病理学对照研究

目的：观察１．５Ｔ ＭＲＩ检出大鼠痫性脑损伤的能力。材料和方法：Ｗｉｓｔａｒ大鼠３０只,毛果云香碱３５０ｍｇ／ｋｇ腹腔注射,诱发反复强真－痉挛全面大发作持续状态,ＨＦ染色,光镜下观察癫痫持续不同时间脑组织损害程度,并与１．５Ｔ ＭＲ成像对比（ＭＲＩ参数：ＳＥ序列Ｔ１加权像：重复时间＝５００ｍｓ,回波时间＝１５ｍｓ;ＦＳＥ序列Ｔ２加权像：重复时间＝４００ｍｓ;用表面线圈,层厚２．２ｍｍ,无间隔）。结果：癫痫持续时间与脑损伤呈相关性改变。癫痫持续３ｄ后,可见颞叶、海马区严重神经元脱失、胶质增生和脑水肿,ＭＲ扫描除在１只发作持续１８ｈ的大鼠左颞区检出长Ｔ１、长Ｔ２异常信号外（光镜提示为在灶）,未发现其余动物脑的结构异常和信号变化。结论：随着动物大发作持续时间延长,痫性脑损害加重,大鼠癫痫持续３ｈ以上,有明显的海马神经     

Infants exposed to MRI in utero have a normal paediatric assessment at 9 months of age

Any differences in detailed paediatric assessment at 9 months of age in infants exposed to echo planar MRI in utero from 20 weeks gestation to term were investigated by performing a case controlled prospective observational study of 20 infants. They had all had serial echo planar MRI in the antenatal period and were compared with a control group born at the same time who had not. Statistical analysis employed likelihood ratios, odds ratios and 95% confidence intervals. The mothers of the control infants had a significantly higher standard of educational attainment (p = 0.005). A small but significant decrease in length (p = 0.047), and an increase in gross motor function (p = 0.023) of the fetuses exposed to echo planar imaging were demonstrated. No other significant developmental or social differences were seen between the two groups. Infants at 9 months of age did not demonstrate any gross abnormality likely to be related to exposure to echo planar MRI in utero.     

高海拔地区小儿重型颅脑损伤105例诊治体会

目的：探讨高海拔地区小儿重型颅脑损伤的诊治预后。方法：回顾性分析我院自1994年8月至2003年8月收治的105例小儿重型颅脑损伤(GCS≤8分)的临床资料。结果：手术治疗70例,非手术治疗35例。死亡23例(21．9％),存活82例(78．1％)。随访8个月至4年,49例恢复正常,29例CT提示脑软化灶,4例继发外伤性癫痫。结论：小儿重型颅脑损伤应尽早确诊,选择及时、有效的治疗方案,是降低死亡率和提高生存质量的关键。     

儿童长骨生长板损伤组织学和影像诊断

目的：认识儿童生长板损伤不同类型的预后及易发生畸形的类型。方法：30例1～9岁儿童肘关节肱骨远端骺软骨骨折X线资料,3例肱骨远端生长板损伤MR成像,4例膝和踝关节生长板骨折MR成像,另有11只实验兔骨骺牵拉延长术后平片、微血管摄影和病理切片。生长板损伤采用Salter-Harris分类法分为5型。结果：第3型,骨折线垂直经过骨骺然后水平向生长板裂开;第4型,骨折经过骨骺穿过生长板至干骺端骨折;第5型,损伤生长板的问叶细胞。上述三种类型都可发生骨骺早闭。而第1型（骨骺牵拉分离）和第2型（骨折线经生长板进入干骺端）一般预后好,不发生畸形。结论：儿童肘关节创伤X线平片和MRI可显示骨折解剖,准确的分型和判断预后是非常重要的。     

脑损伤急性期脑微血管5-羟色胺、多巴胺含量变化与外伤性脑水肿的关系

目的：探讨脑损伤急性期脑微血管中５－羟色胺（５－ＨＴ）、多巴胺（ＤＡ）的含量变化及其与外伤性脑水肿的关系。方法：采用高效液相色谱—电化学检测器，直接检测大鼠脑损伤急性期脑微血管中５－ＨＴ、ＤＡ的含量。结果：脑损伤后０．５小时脑微血管中５－ＨＴ、ＤＡ含量明显增加，伤后６小时仍明显高于对照组，相差非常显著（Ｐ＜０．０１）；同时限检测脑组织水含量明显增高。结论：脑损伤急性期脑微血管中５－ＨＴ、ＤＡ含量明显增高，严重影响脑微血管舒缩功能，损害血脑屏障，可能是外伤性脑水肿发生与发展的重要因素之一。     

肱骨头囊变与年龄和肩袖损伤的相关因素磁共振研究

目的:利用磁共振检查,探讨发生在肱骨头不同部位囊变与肩袖损伤和年龄之间的相关性.方法:回顾性分析289例肩关节磁共振资料.按肱骨头囊变发生的不同部位分四组:肱骨大结节后部(a)和前部(b),肱骨小结节(c),肱骨解剖颈裸区(d).统计对照分析不同部位囊变组与无囊变组的平均年龄和肩袖损伤程度.结果:107例(37.0％)肱骨头发现囊变,经统计学检验:大结节后部囊变组的年龄和肩袖损伤程度均高于无囊变组(P＜0.01);大结节前部囊变组和小结节部囊变组的肩袖损伤程度高于无囊变组(P＜0.01);肱骨解剖颈裸区囊变组的年龄和肩袖损伤程度与无囊变组相比差异无统计学意义.结论:肱骨大结节后部出现囊变提示与年龄和肩袖损伤有关;大结节前部和小结节部出现囊变提示与肩袖损伤有关;而肱骨解剖颈裸区出现囊变与年龄和肩袖损伤无明显关系.     

MRI平扫及增强三维重建技术在视神经损伤中的诊断

目的 探讨MRI三维重建技术在视神经损伤中的诊断价值.方法 13例视神经损伤病例分别行CT、磁共振平扫及增强扫描,并行脂肪抑制T2WI、 T1WI下三维重建.结果 13例视神经管内段和/或眶内段损伤中,CT仅显示视神经管骨折和/或眼眶骨折,视神经均未见异常表现.8例T1WI及T2WI表现为视神经管内段增粗、迂曲,视神经未见异常信号,5例脂肪抑制T2WI表现为视神经异常信号;13例病人经过脂肪抑制T2WI、T1WI平扫及增强扫描下三维重建,均有阳性表现.结论 MRI平扫及增强下三维重建技术在视神经损伤中具有重要的诊断价值.     

Language used in Lake Louise Scoring System underestimates symptoms of acute mountain sickness in 4- to 11-year-old children

The Lake Louise Scoring System (LLSS) was designed to evaluate adults for symptoms of acute mountain sickness (AMS). The language used in the LLSS may be too complex for young children to comprehend. This study evaluates if age-appropriate language alters the results of AMS diagnostic scores in 4- to 11-yr-old children. With parental help, subjects completed the LLSS and an equivalent Lake Louise Age-Adjusted Symptom Score (LLAASS) daily for 3 days. Measurements were made at 1605 m, in the subjects' homes, without any altitude change. Equivalent questions between the two surveys were assessed for agreement on the day when the most symptoms were recorded for each question. Thirty-seven children (19 girls), ages 4 to 11 yr (mean age 7.4 +/- 2.3 yr) completed the study. Kappa values: headache (kappa = 0.22), gastrointestinal (kappa = 0.34), fatigue (kappa = 0.88), dizziness (kappa = 0.65), and sleep (kappa = 0.88) ranged from fair to very good. The LLAASS resulted in higher mean symptom scores (1.14 +/- 0.98) compared to LLSS questions (0.61 +/- 0.82) (p < 0.01). The AMS diagnostic threshold was reached in 9% (95% CI, 4-16) of measurements using the LLAASS and 4.5% (95% CI, 1.5-10) with the LLSS. The LLSS results in reporting of fewer AMS symptoms in this population when compared with a diagnostic tool using age-appropriate language and/or visual representations. Age-appropriate communication must be used to assess AMS, particularly for headache (the key symptom of AMS) and gastrointestinal symptoms. Young children report symptoms of AMS at baseline without altitude gain; therefore, the AMS diagnostic threshold in this population may require modification.     

MRI Inter-Reader and Intra-Reader Reliabilities for Assessing Injury Morphology and Posterior Ligamentous Complex Integrity of the Spine According to the Thoracolumbar Injury Classification System and Severity Score

ObjectiveTo evaluate spine magnetic resonance imaging (MRI) inter-reader and intra-reader reliabilities using the thoracolumbar injury classification system and severity score (TLICS) and to analyze the effects of reader experience on reliability and the possible reasons for discordant interpretations.ResultsInter-reader agreement between the six readers was moderate (k = 0.538 for the first and 0.537 for the second review) for injury morphology and fair to moderate (k = 0.440 for the first and 0.389 for the second review) for PLC integrity. No significant difference in inter-reader agreement was observed according to the number of years of radiologist experience. Intra-reader agreements showed a wide range (k = 0.538-0.822 for injury morphology and 0.423-0.616 for PLC integrity). Agreement was achieved in 44 for the first and 45 for the second review about injury morphology, as well as in 41 for the first and 38 for the second review of PLC integrity. A positive correlation was detected between injury morphology score and PLC integrity.ConclusionThe reliability of MRI for assessing thoracolumbar spinal injuries according to the TLICS was moderate for injury morphology and fair to moderate for PLC integrity, which may not be influenced by radiologist'' experience.     

Measurement of Lactate Content and Amide Proton Transfer Values in the Basal Ganglia of a Neonatal Piglet Hypoxic-Ischemic Brain Injury Model Using MRI

BACKGROUND AND PURPOSE:As amide proton transfer imaging is sensitive to protein content and intracellular pH, it has been widely used in the nervous system, including brain tumors and stroke. This work aimed to measure the lactate content and amide proton transfer values in the basal ganglia of a neonatal piglet hypoxic-ischemic brain injury model by using MR spectroscopy and amide proton transfer imaging.MATERIALS AND METHODS:From 58 healthy neonatal piglets (3–5 days after birth; weight, 1–1.5 kg) selected initially, 9 piglets remained in the control group and 43 piglets, in the hypoxic-ischemic brain injury group. Single-section amide proton transfer imaging was performed at the coronal level of the basal ganglia. Amide proton transfer values of the bilateral basal ganglia were measured in all piglets. The ROI of MR spectroscopy imaging was the right basal ganglia, and the postprocessing was completed with LCModel software.RESULTS:After hypoxic-ischemic insult, the amide proton transfer values immediately decreased, and at 0–2 hours, they remained at their lowest level. Thereafter, they gradually increased and finally exceeded those of the control group at 48–72 hours. After hypoxic-ischemic insult, the lactate content increased immediately, was maximal at 2–6 hours, and then gradually decreased to the level of the control group. The amide proton transfer values were negatively correlated with lactate content (r = −0.79, P < .05).CONCLUSIONS:This observation suggests that after hypoxic-ischemic insult, the recovery of pH was faster than that of lactate homeostasis.

The neonatal brain is in a process of continuous development and maturation and has a great demand for oxygen. Normally, brain activities are primarily supported by energy produced from the aerobic metabolism of glucose.^1–3 In a physiologic state, 90%–95% of brain energy is consumed by neurons, but 80% of glucose use happens in astrocytes, which suggests that a glucose mesostate released by astrocytes is absorbed and used by neurons to support their high energy consumption. A study⁴ has shown that during glucose metabolism in the brain, lactate is a carrier of energy and facilitates interaction between astrocytes and neurons. Astrocytes absorb glucose and transform it into lactate and then provide lactate to neurons. Therefore, lactate is an important mesostate during energy metabolism in the brain.Normally, this astrocyte-neuron-lactate shuttle maintains a dynamic balance. However, when the brain is exposed to a hypoxic-ischemic (HI) environment, aerobic energy metabolism is interrupted^5–7 and becomes anaerobic. During anaerobic metabolism, lactate is produced, causing an increase of lactate in brain tissue. As a result, the accumulated lactate suppresses glucose metabolism and uses up adenosine triphosphate, thus exacerbating intracellular acidosis.^8,9 Meanwhile, lactate is a crucial substrate for neurons that restores aerobic energy metabolism after an HI insult and plays an important role in the early stage of HI insult. Therefore, the study of lactate metabolism changes in the brain after HI insult furthers the understanding of neuronal energy metabolism and post-hypoxic-ischemic brain injury (HIBI) neuronal energy recovery and neuron protection mechanisms.Brain acidosis often occurs after HI insult, for which the adjustment of the brain pH is critical. pH is especially important for protein structure and enzyme activity in the brain. Therefore, it is essential to timely detect and regulate the intracellular pH of brain tissues.Amide proton transfer (APT) imaging is a recently developed MR imaging technique. In theory, APT signal intensity primarily depends on the exchange rate between amide protons and water protons^10–12; this exchange rate is associated with the protein content, pH, and temperature. If it is assumed that other variables remain unchanged, when the pH decreases, the exchange rate slows and APT signal intensity weakens.^13–15 Thus, APT imaging can also be considered pH-weighted imaging. The magnetization transfer ratio asymmetry (3.5 ppm) is called the amide proton transfer–weighted (APTw) intensity, to reflect the APT effect, which is contaminated by the conventional magnetization transfer ratio asymmetry and nuclear Overhauser enhancement.In the normal physiologic state, lactate is absent or rare,¹⁶ but in an HI environment, lactate is increased; this change indicates enhanced anaerobic metabolism. To date, studies that explore the role of lactate in energy metabolism, particularly in neuron recovery after hypoxic-ischemic brain injury, and investigate the noninvasive detection of intracellular pH in brain tissues are few but promising. In the present study, we simulated pathophysiologic changes by using a neonatal piglet HIBI model and simultaneously evaluated the time course of lactate and APT changes in hypoxic-ischemic injury.     

T2- and diffusion-maps reveal diurnal changes of intervertebral disc composition: an in vivo MRI study at 1.5 Tesla

PURPOSE: To investigate the lumbar intervertebral discs (IVDs) by MRI in the morning and evening after a diurnal load cycle. Changes in MR characteristics (T2-weighted imaging, T2- and apparent diffusion coefficient [ADC] -mapping) during the course of the day were visualized and analyzed visually and quantitatively. The length of the lumbar spine was measured in between the lower anterior edge of Th12 and the upper anterior edge of S1. T2 changes and diffusion characteristics of the vertebral disc tissue were investigated with a higher spatial resolution than in former studies. MATERIALS AND METHODS: In six males, lumbar IVDs were investigated in the morning and evening. T2-maps and ADC maps were generated. Data were analyzed by selecting regions of interest (ROI) in the annulus fibrosus (AF), nucleus pulposus (NP), and an intermediate area. RESULTS: From morning to evening, T2 decreased in the center of the NP (-7.9%; P = 0.001) and the intermediate voxels (-6.4%; P < 0.0005). T2 increased (8.5%; P < 0.048) in the AF. ADC decreased in the AF (-5.2%; P = 0.007) and the intermediate ROIs (-2.2%; P = 0.004). There was no significant change of ADC in the NP (-1.6%; P = 0.242). CONCLUSION: T2 and diffusion (ADC) changes of IVDs in humans were investigated with a spatial differentiation between NP and AF. T2 and ADC turned out to be sensitive parameters in investigating changes in the MR characteristics of the IVD matrix during a day. Highly resolved MR imaging and parameter mapping is expected to be an interesting tool in characterizing structural changes in the vertebral disc architecture in an early stage of degeneration.     

3.0T磁敏感加权成像评价弥漫性轴索损伤及与昏迷评分相关性

目的 研究磁共振磁敏感加权成像(SWI)对脑弥漫性轴索损伤的诊断价值及其与临床格拉斯哥昏迷计分表(GCS)评分的相互关系.方法 收集临床诊断弥漫性轴索损伤的患者40例,均行常规T1WI、T2WI、FLAIR及SWI成像.结果 SWI在40例弥漫性轴索损伤患者中,均能较常规序列上清楚地更多显示脑内微小出血灶.GCS计分13～15分23例,9～12分12例,≤8分5例.结论 SWI可在很大程度上为临床早期诊断弥漫性轴索损伤和在治疗方案的制订及评估预后中提供帮助.