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。     

Fetal magnetic resonance imaging: jumping from 1.5 to 3 tesla (preliminary experience)

Several attempts have been made at imaging the fetus at 3 T as part of the continuous search for increased image signal and better anatomical delineation of the developing fetus. Until very recently, imaging of the fetus at 3 T has been disappointing, with numerous artifacts impeding image analysis. Better magnets and coils and improved technology now allow imaging of the fetus at greater magnetic strength, some hurdles in the shape of imaging artifacts notwithstanding. In this paper we present the preliminary experience of evaluating the developing fetus at 3 T and discuss several artifacts encountered and techniques to decrease them, as well as safety concerns associated with scanning the fetus at higher magnetic strength.     

新生儿低血糖脑损伤早期MRI表现及其演变

目的 通过对低血糖患儿进行低血糖后早期、动态的MRI检查,结合临床特征探讨不同程度低血糖脑损伤患儿的MRI改变。方法 选取我院2005年5月至2013年7月以低血糖收入院,在低血糖后1周内完善首次常规MRI及弥散加权成像（diffusion-weighted imaging,DWI）检查确诊为新生儿低血糖脑损伤的患儿49例。其中34例在低血糖发生后2～3周完善第2次MRI检查,7例完善第3次MRI检查。结果 49例患儿首次MRI均有顶、枕部受累;顶、枕部受累为主33例,顶、枕部合并额叶、颞叶受累6例,弥漫性皮层及皮层下白质受累10例。均表现为受累部位DWI高信号,T1和T2加权像信号改变不明显。部分患儿合并深部脑白质及灰质受累表现。34例患儿第2次MRI检查,有20例表现为损伤部位DWI低信号,T1加权像低信号,T2加权像高信号,3例较前略吸收,11例未见异常信号。7例患儿完善第3次复查,分别出现脑软化,髓鞘发育落后,白质容积减小,胼胝体发育不良。对比不同程度脑损伤患儿的临床症状,发现临床症状较重者脑损伤也较重。结论 低血糖脑损伤具有顶、枕部易损性。低血糖后1周内完善DWI检查对急性期低血糖脑损伤有提示作用。MRI动态观察发现轻症损伤可恢复。损伤较重的患儿可出现坏死及脑软化。部分合并深部白质、灰质损伤的病例,不能除外缺氧缺血所致。     

Magnetic resonance imaging in perinatal brain injury: clinical presentation, lesions and outcome

Neonatal MR imaging is invaluable in assessing the term born neonate who presents with an encephalopathy. Successful imaging requires adaptations to both the hardware and the sequences used for adults. The perinatal and postnatal details often predict the pattern of lesions sustained and are essential for correct interpretation of the imaging findings, but additional or alternative diagnoses in infants with apparent hypoxic ischaemic encephalopathy should always be considered. Perinatally acquired lesions are usually at their most obvious between 1 and 2 weeks of age. Very early imaging (<3 days) may be useful to make management decisions in ventilated neonates, but abnormalities may be subtle at that stage. Diffusion-weighted imaging is clinically useful for the early identification of ischaemic white matter in the neonatal brain but is less reliable in detecting lesions within the basal ganglia and thalami. The pattern of lesions seen on MRI can predict neurodevelopmental outcome. Additional useful information may be obtained by advanced techniques such as MR angiography, venography and perfusion-weighted imaging. Serial imaging with quantification of both structure size and tissue damage provides invaluable insights into perinatal brain injury.     

MRI of perinatal brain injury

MRI is invaluable in assessing the neonatal brain following suspected perinatal injury. Good quality imaging requires adaptations to both the hardware and the sequences used for adults or older children. The perinatal and postnatal details often predict the pattern of lesions sustained and should be available to aid interpretation of the imaging findings. Perinatal lesions, the pattern of which can predict neurodevelopmental outcome, are at their most obvious on conventional imaging between 1 and 2 weeks from birth. Very early imaging during the first week may be useful to make management decisions in ventilated neonates but brain abnormalities may still be subtle using conventional sequences. Diffusion-weighted imaging (DWI) is very useful for the early identification of ischaemic tissue in the neonatal brain but may underestimate the final extent of injury, particularly basal ganglia and thalamic lesions. MR imaging is an excellent predictor of outcome following perinatal brain injury and can therefore be used as a biomarker in interventional trials designed to reduce injury and improve neurodevelopmental outcome.     

Longitudinal assessment of hippocampus structure in children with type 1 diabetes

The extant literature finds that children with type 1 diabetes mellitus (T1D) experience mild cognitive alterations compared to healthy age‐matched controls. The neural basis of these cognitive differences is unclear but may relate in part to the effects of dysglycemia on the developing brain. We investigated longitudinal changes in hippocampus volume in young children with early‐onset T1D. Structural magnetic resonance imaging data were acquired from 142 children with T1D and 65 age‐matched control subjects (4‐10 years of age at study entry) at 2 time points, 18 months apart. The effects of diabetes and glycemic exposure on hippocampal volume and growth were examined. Results indicated that although longitudinal hippocampus growth did not differ between children with T1D and healthy control children, slower growth of the hippocampus was associated with both increased exposure to hyperglycemia (interval HbA1c) and greater glycemic variability (MAGE) in T1D. These observations indicate that the current practice of tolerating some hyperglycemia to minimize the risk of hypoglycemia in young children with T1D may not be optimal for the developing brain. Efforts that continue to assess the factors influencing neural and cognitive development in children with T1D will be critical in minimizing the deleterious effects of diabetes.     

Optimized T1- and T2-weighted volumetric brain imaging as a diagnostic tool in very preterm neonates

Background  

T1- and T2-W MR sequences used for obtaining diagnostic information and morphometric measurements in the neonatal brain are frequently acquired using different imaging protocols. Optimizing one protocol for obtaining both kinds of information is valuable.     

A primer on brain imaging in developmental psychopathology: What is it good for?

This primer introduces a Special Section on brain imaging, which includes a commentary and 10 data papers presenting applications of brain imaging to questions on developmental psychopathology. This primer serves two purposes. First, the article summarizes the strength and weaknesses of various brain-imaging techniques typically employed in research on developmental psychopathology. Second, the article places research on brain imaging in a broader context by discussing particular limitations and utilities of imaging. Specifically, while brain imaging is currently of limited clinical utility, work in this area is beginning to shape clinical thinking. Brain-imaging research offers a unique opportunity to constrain theories of pathophysiology based on understandings of brain function. This effect promises to open avenues for novel treatments.     

Brain injury in glutaric aciduria type I: The value of functional techniques in magnetic resonance imaging

BackgroundAcute striatal necrosis is a devastating consequence of encephalopathic crisis in patients with glutaric aciduria type I (GA-I), but the mechanisms underlying brain injury are not completely understood.ObjectiveTo approach pathophysiological aspects of brain injury in GA-I by means of functional techniques in magnetic resonance imaging (MRI).Patients and methodsFour patients during an acute encephalopathic crisis and three asymptomatic siblings with GA-I underwent single-voxel hydrogen magnetic resonance spectroscopy (MRS) and brain MRI including gradient echo T1-weighted, FLAIR, T2-weighted and diffusion-weighted imaging.ResultsThe study was performed between three and eight days after the onset of acute encephalopathic crisis. Isotropic diffusion images showed high signal changes with corresponding low apparent diffusion coefficient values within the putamen, caudate nuclei and globus pallidus (four patients), and the cerebral peduncles including the substantia nigra (one patient). The study disclosed normal findings in asymptomatic siblings. MRS showed decreased N-acetyl-aspartate/creatine ratio at the basal ganglia in encephalopathic patients when compared to a group of sex- and age-matched controls.ConclusionsBrain injury in GA-I is characterizied by the presence of cytotoxic edema and reduced neuronal integrity by functional imaging techniques. Involvement of the basal ganglia may be asymmetrical in patients with unilateral motor disorder and may extent to the cerebral peduncles and substantia nigra, which may be responsible for the acute onset dystonia in some patients. Functional techniques failed to demonstrate any abnormalities in asymptomatic patients, which is in agreement with the integrity of basal ganglia structures observed by conventional MRI sequences.     

弥散加权成像在新生儿重度缺氧缺血性脑病早期评价中的意义

目的探索新生儿重度缺氧缺血性脑病（HIE）早期弥散加权成像（DWI）动态演变规律及其意义。方法对2006年1月至2007年2月收住我院14例重度HIE患儿,分别于生后72h。7、14、21d及8个月行DWI及常规MRI扫描。结果72h内,常规MRI的T1加权（T1WI）和T2加权（T2WI）均未见异常,DWI表现为双侧腹外侧丘脑对称性的高信号;7d常规MRI表现双侧腹外侧丘脑对称性T1WI高信号,T2WI稍低信号,DWI表现为双侧基底节高信号,而初期腹外侧丘脑高信号消失;14d常规MRI双侧丘脑、基底节对称性T1WI高信号,T2WI低信号;21d常规MRI双侧丘脑及基底节T1WI高信号,T2WI高信号,DWI则未见明显异常;8个月常规MRI脑沟变深、脑室扩大及脑外间隙增宽,基底节T2WI不规则的高信号。结论重度HIE（主要因急性的完全性窒息所致）生后初期DWI显示相同的病变部位（腹外侧丘脑和基底节）和相似的病变程度,但其异常信号很快消失,而常规MRI可继之弥补DWI的不足。     

CT versus MR in neonatal brain imaging at term

BACKGROUND: Recent reports have highlighted the lifetime risk of malignancy from using ionizing radiation in pediatric imaging. Computed tomography (CT), which uses ionizing radiation, is employed extensively for neonatal brain imaging of term infants. Magnetic resonance (MR) provides an alternative that does not use ionizing radiation. OBJECTIVE: The purpose of this study was to assess the cross-modality agreement and interobserver agreement of CT and MR brain imaging of the term or near-term neonate. MATERIALS AND METHODS: Brain CT and MR images of 48 neonates were retrospectively reviewed by two pediatric neuroradiologists. CT and MR examinations had been obtained within 72 h of one another in all patients. CT was obtained with 5 mm collimation (KV=120, mAs=340). MR consisted of T1-weighted imaging (TR/TE=300/14; 4-mm slice thickness/1-mm gap), T2-weighted imaging (TR/TE/etl= 3000/126/16; 4-mm slice thickness/1-mm gap), and line scan diffusion imaging (LSDI) (TR/TE/b factor=1258/63/750; nominal 4-mm slice thickness/3-mm gap). The brain was categorized as normal or abnormal on both CT and MR. RESULTS: Ischemic injury was the most common brain abnormality demonstrated. McNemar's test indicated no significant difference between CT and MR test results for reader 1 (P=0.22) or reader 2 (P=0.45). The readers agreed on the presence or absence of abnormality on CT in 40 patients (83.3%) and on MR in 45 patients (93.8%). For CT, the kappa coefficient indicated excellent interobserver agreement (kappa=0.68), although the lower limit of the 95% confidence interval extends to kappa=0.55, which indicates only good-to-moderate agreement. For MR, the kappa coefficient indicated almost perfect interobserver agreement (kappa=0.88) with the 95% confidence interval extending to a lower limit of kappa=0.76, which represents excellent agreement. CONCLUSION. Because MR demonstrates findings similar to CT and has greater interobserver agreement, it appears that MR is a superior test to CT in determining brain abnormalities in the term neonate. Furthermore, since MR eliminates the use of ionizing radiation, a putative cause of malignancy, it should be the standard in neonatal brain imaging. Future efforts should be directed to improving neonatal access to MR to avoid the routine use of CT in infants.     

Technical challenges and safety of magnetic resonance imaging with in situ neuromodulation from spine to brain

Purpose

This review summarises the need for MRI with in situ neuromodulation, the key safety challenges and how they may be mitigated, and surveys the current status of MRI safety for the main categories of neuro-stimulation device, including deep brain stimulation, vagus nerve stimulation, sacral neuromodulation, spinal cord stimulation systems, and cochlear implants.

Magnetic resonance imaging and dexamethasone therapy for bacterial meningitis

We conducted a third placebo-controlled, double-blind study of dexamethasone as adjunctive therapy for bacterial meningitis. Thirty-one patients received cefuroxime sodium (300 mg/kg per day in 3 doses) and dexamethasone phosphate (0.6 mg/kg per day in 4 doses for 4 days), and 29 received cefuroxime and placebo. The groups were comparable at the beginning of therapy. Magnetic resonance imaging performed between days 2 and 5 of therapy was used to assess brain water content indirectly. There were no differences between the 2 treatment groups with respect to the T1- or T2-weighted images. Fifty-two patients (88%) had normal magnetic resonance images; 5 patients had parietal or bifrontal extra-axial fluid collections, and 2 children had areas of abnormal signal intensity in the brain on T2-weighted images. Abnormal findings on magnetic resonance imaging did not alter clinical management, and there was no correlation between the results of magnetic resonance imaging and the outcome of meningitis. The number of patients in this study was too small to determine any statistically significant differences in rates of hearing impairment; however, the cerebrospinal fluid findings and clinical outcome in dexamethasone-treated patients further support the previously reported beneficial effect of corticosteroid treatment in patients with bacterial meningitis.     

Magnetic resonance imaging in hypoxic-ischaemic encephalopathy

Magnetic resonance imaging of the brain is invaluable in assessing the neonate who presents with encephalopathy. Successful imaging requires adaptations to both the hardware and sequences used for adults. Knowledge of the perinatal and postnatal details are essential for the correct interpretation of the imaging findings. Perinatal lesions are at their most obvious on conventional imaging between 1 and 2 weeks from delivery. Very early imaging is useful to guide management in ventilated neonates but abnormalities may be subtle on conventional sequences. Diffusion-weighted imaging (DWI) is clinically useful for the early identification of ischaemic tissue in the neonatal brain, the pattern of which can predict outcome. DWI may underestimate the final extent of injury, particularly basal ganglia and thalamic lesions. Serial imaging with quantification of both tissue damage and structure size provides invaluable insights into the effects of perinatal injury on the developing brain.     

治疗延迟的苯丙酮尿症患儿脑髓鞘发育延迟与智力发育的研究

目的　应用磁共振成像(MRI)观察苯丙酮尿症(PKU)治疗延迟患儿治疗前后脑髓鞘发育延迟与智商的关系。方法　2 0 0 2～2 0 0 3年中日友好医院确诊经典型治疗延迟PKU患儿1 7例,治疗前后分别进行头颅MRI及智商检查,脑髓鞘发育按Staudt标准对不同年龄阶段患儿1 0个脑区域进行量化评估。智商检测采用Gesell发育量表测定。结果　治疗前所有病例存在脑髓鞘发育延迟,在1 0个脑区域脑髓鞘发育延迟平均发生率为44 . 7% ,主要部位在脑叶和胼胝体,并存在不同程度的智力发育落后,平均智商为44 .2 ;经低苯丙氨酸饮食治疗1年后,1 0个脑区域髓鞘发育延迟平均发生率为3 0 . 6% ,平均智商为60 . 6;治疗前、后脑髓鞘延迟改善有显著性(P <0. 0 1 ) ,平均智商改善有统计学意义(P <0. 0 5) ,且智商改善率与髓鞘延迟改善率间可见部分相关性。结论　治疗延迟的PKU患儿的脑髓鞘发育延迟及智力发育落后发生率较高,经低苯丙氨酸饮食治疗可使其在一定程度有所改善,但不能达到完全正常,提示脑髓鞘发育延迟可能是导致PKU患儿智力发育落后的原因之一。     

Imaging of arteriovenous malformation following stereotactic radiosurgery

Background. Stereotactic radiosurgery allows for a high dose of focused radiation to be delivered to a small lesion such as an arteriovenous malformation (AVM). The clinical change and brain response over time to this localized high-dose radiation can be quite striking. Objective. The objective of this study to describe and analyse the imaging changes following radiotherapy for AVMs. Materials and methods. The clinical presentation and the imaging changes following radiotherapy in two patients were studied over the course of 1–2 years. Results. The imaging findings include diffuse low attenuation and contrast enhancement on CT. High-signal lesions were apparent on T2-weighted MR images with prominent contrast enhancement on T1-weighted images. Ring enhancement occurred over time. While new changes appeared over 12 months, these changes diminished during the second year. Conclusion. Radiotherapy induces inflammatory changes that are generally reversible but can lead to parenchymal destruction. These imaging changes are often nonspecific and therefore must be interpreted in light of clinical symptomatology and the time course since treatment. These patients should receive routine MR imaging within 3 months after radiosurgery with follow-up imaging at 6, 12, and 18 months. Received: 13 February 1996 Accepted: 29 June 1996     

Progrès récents de l’imagerie par résonance magnétique (IRM) chez le nouveau-né

The accurate morphological exploration of the brain is a major challenge in neonatology that advances in magnetic resonance imaging (MRI) can now provide. MRI is the gold standard if an hypoxic ischemic pathology is suspected in a full term neonate. In prematures, the specific role of MRI remains to be defined, secondary to US in any case. We present a state of the art of hardware and software technical developments in MRI. The increase in magnetic field strength (3 tesla) and the emergence of new MRI sequences provide access to new information. They both have positive and negative consequences on the daily clinical data acquisition use. The semiology of brain imaging in full term newborns and prematures is more extensive and complex and thereby more difficult to interpret. The segmentation of different brain structures in the newborn, even very premature, is now available. It is now possible to dissociate the cortex and basal ganglia from the cerebral white matter, to calculate the volume of anatomical structures, which improves the morphometric quantification and the understanding of the normal and abnormal brain development. MRI is a powerful tool to analyze the neonatal brain. The relevance of the diagnostic contribution requires an adaptation of the parameters of the sequences to acquire and of the image processing methods.     

Feasibility of 3-T MRI for the evaluation of Crohn disease in children

Background  

Crohn disease (CD) is a chronic inflammatory bowel disease that can affect any part of the gastrointestinal tract from the oral cavity to the anal canal. It occurs in all ages and is a significant cause for morbidity in children. Interest in MRI evaluation of CD has increased because of the concern regarding cumulative radiation dose from contrast fluoroscopic studies and CT. Several reports have demonstrated MRI to be a useful technique for CD. Most of these studies were performed at 1.5-T field strength. Imaging at a higher field strength, with a greater signal-to-noise ratio, has the potential of reducing scan times and increasing the resolution. However, there is a concurrent increase in artefacts, and these can be pronounced with abdominal imaging at 3 T.