The clinical and radiological evaluation of primary brain neoplasms in children, Part II: Radiological evaluation.

Data collected over the past 8 years on the radiological appearance of common pediatric primary brain neoplasms are presented. An emphasis is placed on the newer radiological imaging modality of magnetic resonance imaging (MRI). Part I of this article emphasized the clinical evaluation of these brain neoplasms. Three hundred eighty-five children with known brain neoplasms ranging in age from newborn to 18 years were evaluated with one or all of the following radiological modalities: MRI, computed tomography (CT), water-soluble myelography (WSM), WSM with CT, and angiography. Contrast-enhanced MRI and CT scans both were accurate in delineating these brain neoplasms although MRI provided better resolution and delineation than CT. Angiography provided information on the vascularity of the neoplasms and their relationship to prominent arterial and venous structures. Water-soluble myelography with CT and gadolinium-enhanced MRI of the spine were equally accurate in demonstrating metastatic spread to the spinal canal and spinal cord. Magnetic resonance imaging with gadolinium was more accurate than CT with contrast in demonstrating recurrent or residual neoplasm at the operative site and metastatic spread to the brain. Magnetic resonance imaging with gadolinium is the best radiological modality to fully evaluate pediatric brain neoplasms.     

Lambdoid synostosis is an overdiagnosed condition

To address the controversy regarding the relationship between cognitive impairment (lowering of IQ) and magnetic resonance imaging (MRI) characteristics (T2-weighted hyperintensities or unidentified bright objects [UBOs]) in children with neurofibromatosis-1 (NF-1), we used a pairwise NF-1/ sibling design; we set out to predict the lowering of IQ in each child with NF-1 as a discrepancy from the IQ of an unaffected sibling (D-SIQ). Our multiple regression model included the age of the child with NF-1, familial or sporadic nature of the NF-1, number of locations in the child's brain occupied by T2-weighted hyperintensities (UBOs), and the volumetric percentage of brain tissue occupied by T2-weighted hyperintensities (UBOs). Only the number of locations occupied by UBOs accounted for IQ lowering (D-SIQ) in children with NF-1 (42% of the variance in D-SIQ). This is the first report to confirm that a continuum of lowered IQs in NF-l-affected children exists in relation to the distribution of UBOs (range 0–7), not just presence (vs. absence) of any UBOs. © 1996 Wiley-Liss, Inc.     

Lactoferrin-conjugated superparamagnetic iron oxide nanoparticles as a specific MRI contrast agent for detection of brain glioma in vivo

A specific contrast agent for magnetic resonance imaging (MRI) is crucial to brain tumor patients for the surgical operation or the postoperative radiology. This study explored lactoferrin-conjugated superparamagnetic iron oxide nanoparticles (Lf-SPIONs) as an MRI contrast agent for the detection of brain gliomas in vivo. The hydrodynamic diameter of about 75 nm, saturation magnetization of 51 emu/g Fe and T(2) relaxivity of 75.6 mM(-1)S(-1) of the Lf-SPIONs suggested its applicability for MRI. Using a rat model of C6 glioma, Lf-SPIONs provided a better picture or more sensitivity to depict brain glioma on MR images than that of SPIONs. Significantly enhanced T(2)-weighted images of brain glioma were documented in vivo with Lf-SPIONs until 48 h after injection. Moreover, Lf-SPIONs were clearly observed around vascular region of the tumor slices after 48 h. High level expression of Lf receptors was confirmed in brain tumor tissues by RT-PCR and Western Blot compared to normal brain tissues. These findings suggested that Lf-SPIONs could be potentially employed as a sensitive and specific MRI contrast agent in the diagnosis of brain glioma.     

Successful steroid pulse therapy for brain lesion caused by Shiga toxin 2 in rabbits

Betamethasone sodium phosphate (BSP) is usually used as a steroid therapy for human brain edema. High doses of BSP (36 mg/kg) twice a day for two days statistically reduced the mortality rate and improved the survival period of Stx2 (1.4 μg/kg; 1.6LD₅₀)-toxemic rabbits. We made evaluations on three kinds of magnetic resonance images (MRI) including T1-weighted, T2-weighted, and enhanced MRI using gadopentetate dimeglumine (Gd-DTPA) to detect brain lesion induced by an intravenous injection of Stx2 in rabbits. Enhanced T1-weighted MRI was the most sensitive tool to find leakage of Gd-DTPA suggesting impairment of the blood brain barrier caused by Stx2. Enhanced MRI revealed that BSP treatment inhibited the leakage of Gd-DTPA, as directly evidenced by the protective effect of BSP against brain edema induced by intravenous injection of Stx2. Interleukin 1β was not induced after Stx2 treatment in brain primary mixed cell culture.     

Early Experience of Pre- and Post-Contrast 7.0T MRI in Brain Tumors

We investigated the safety and clinical applicability of 7.0 Tesla (T) brain magnetic resonance imaging (MRI) in patients with brain tumors. Twenty-four patients with intraaxial or extraaxial brain tumors were enrolled in this study. 7.0T MRIs of T2*-weighted axial and T1-weighted coronal or sagittal images were obtained and compared with 1.5T brain MRIs. The T2*-weighted images from 7.0T brain MRI revealed detailed microvasculature and the internal contents of supratentorial brain tumors better than that of 1.5T brain MRI. For brain tumors located in parasellar areas or areas adjacent to major cerebral vessels, flow-related artifacts were exaggerated in the 7.0T brain MRIs. For brain tumors adjacent to the skull base, susceptibility artifacts in the interfacing areas of the paranasal sinus and skull base hampered the aquisition of detailed images and information on brain tumors in the 7.0T brain MRIs. This study shows that 7.0T brain MRI can provide detailed information on the intratumoral components and margins in supratentorial brain tumors. Further studies are needed to develop refined MRI protocols for better images of brain tumors located in the skull base, parasellar, and adjacent major cerebrovascular structures.     

Neuroimaging and functional analyses for multiple sclerosis

For neuroimaging studies of multiple sclerosis(MS) lesions, magnetic resonance imaging (MRI) is most useful, while evoked potentials(EPs) are commonly used for functional analyses of neural damage due to MS. This review summarizes the MRI and EP findings in MS. MS lesions are visualized as high signal intensity lesions on T2-weighted images, proton density(PD)-weighted images, and fluid-attenuated inversion recovery(FLAIR) images, while such lesions demonstrate a low signal on T1-weighted images. New MS lesions are usually enhanced by gadolinium-DTPA on T1-weighted images, and the enhancement generally lasts 4 to 8 weeks. In Asian patients with MS, opticospinal MS(Asian-type MS) shows a significantly smaller numbers of brain MRI lesions than conventional MS(Western-type MS), while opticospinal MS shows a significantly higher frequency of the spinal cord atrophy on MRI than conventional MS. EPs are useful for detecting lesions located in certain portions of the central nervous system. MRI is not sensitive enough to detect small lesions in the optic nerves and spinal cord, whereas EPs are sensitive for optic nerve and spinal cord lesions. Thus, combined use of MRI and EPs is required for the diagnosis and the optimal monitoring of disease activity in MS.     

Magnetic resonance imaging demonstrates incomplete myelination in 18q- syndrome

Magnetic resonance imaging (MRI) and MRI relaxometry were used to investigate disturbed brain myelination in 18q- syndrome, a disorder characterized by mental retardation, dysmorphic features, and growth failure. T1-weighted and dual spin-echo T2-weighted MR images were obtained, and T1 and T2 parametric image maps were created for 20 patients and 12 controls. MRI demonstrated abnormal brain white matter in all patients. White matter T1 and T2 relaxation times were significantly prolonged in patients compared to controls at all ages studied, suggesting incomplete myelination. Chromosome analysis using fluorescence in situ hybridization techniques showed that all patients with abnormal MRI scans and prolonged white matter T1 and T2 relaxation times were missing one copy of the myelin basic protein (MBP) gene. The one patient with normal-appearing white matter and normal white matter T1 and T2 relaxation times possessed two copies of the MBP gene. MRI and molecular genetic data suggest that incomplete cerebral myelination in 18q- is associated with haploinsufficiency of the gene for MBP. Am. J. Med. Genet. 74:422–431, 1997. © 1997 Wiley-Liss, Inc.     

Fully automatic brain extraction algorithm for axial T2-weighted magnetic resonance images

In this paper we propose two brain extraction algorithms (BEA) for T2-weighted magnetic resonance imaging (MRI) scans. The T2-weighted image is first filtered with a low pass filter (LPF) to remove or subdue the background noise. Then the image is diffused to enhance the brain boundaries. Using Ridler’s method a threshold value for intensity is obtained. Using the threshold value a rough binary brain image is obtained. By performing morphological operations and using the largest connected component (LCC) analysis, a brain mask is obtained from which the brain is extracted. This method uses only 2D information of slices and is named as 2D-BEA. The concept of LCC failed in few slices. To overcome this problem, 3D information available in adjacent slices is used which resulted in 3D-BEA. Experimental results on 20 MRI data sets show that the proposed 3D-BEA gave excellent results. The performance of this 3D-BEA is better than 2D-BEA and other popular methods, brain extraction tool (BET) and brain surface extractor (BSE).     

椎间隙感染的MRI诊断

目的：分析椎间隙感染的MRI影像特征，评价椎间隙感染的MRI诊断价值。方法：对15例经临床或手术病理证实的椎间隙感染患者行脊柱MRI检查，扫描序列为矢状面FrFsE-T1WI、FrFSE-T2WI、脂肪抑制T2WI，横断面FrFSE-T2WI，其中5例行Gd-DTPA增强对比扫描。结果：15例患者共发现17个椎间隙感染，其中15个发生于腰椎间隙。椎间隙狭窄(13个)，病变椎间盘呈不同程度破坏、碎裂，呈长T1(17个)长T2(15个)信号，T2上椎间盘髓核内正常裂隙状低信号消失(13个)，上下相邻椎体受累破坏(15个)，椎旁软组织肿胀(8个)。5例行Gd-DT-PA增强对比扫描可见病变椎间盘、相邻椎体及椎旁软组织异常强化。结论：MRI对诊断椎间隙感染具有很高的敏感性和准确性，应作为首选的影像学检查方法：     

A case of intraosseous arteriovenous malformation with unusual radiological presentation of low blood flow

We report a case of intraosseous arteriovenous malformation (AVM) arising in the diaphysis of the tibia. The patient was a 15-year-old boy who presented with pain in the right lower leg for 3 years. Plain radiographs displayed honeycomb lytic lesions in the right tibial shaft, with slight expansion of the bone and cortical thinning. The lesion was isointense to the muscle on T1-weighted images, and hyperintense on T2-weighted images. An admixture of hypointense small nodular or linear areas on both T1- and T2-weighted images was present within the lesion. Post contrast fat-suppressed T1-images demonstrated a mild heterogeneous increase in signal intensity throughout the tumor. Angiographs showed only faint staining in the lesion. Curettage of the lesion was carried out, and the histological diagnosis of AVM was made. In the context of this patient's lesion, it should be noted that AVM rarely presents as an intraosseous lesion with low blood flow.     

Tanycytic ependymoma: two case reports and review of the literature

Two cases of tanycytic ependymoma are reported, one in a woman aged 33 years and one in a man aged 36 years. The woman presented with lesions at L2 and L3 in the spinal cord and clinical symptoms suggested spinal cord compression, such as movement and sensory dysfunction. The man had a lesion located in the lateral ventricle and presented with headache, vomiting, and impaired vision. Both of these patients developed gradual increases in the intensity of their symptoms over a few months prior to admission. A spinal cord MRI of the woman showed a well-defined, solid cystic mass measuring 1.0 × 6.5 cm at L2 and L3 of the spinal cord. The mass showed low signal intensity on T2-weighted images in the intervertebral disc with equal signal intensity T1-/T2-weighted images. The signal was uniform and enhanced scanning showed a light strengthening of signal. A brain MRI of the man showed a well-defined mass measuring 4 cm in diameter invading the right ventricle. The mass showed low signal intensity on right T1-weighted images and high signal intensity on T2-weighted images. Histopathologically, the tumors were rich with significant and uniform proliferation of long spindle cells, which were arranged in fasciculate and knitted patterns with bipolar and spindled processes focally forming perivascular pseudorosettes. The cell nuclei showed minor pleomorphism. A few tumor cells centered on the vessels resulted in a nuclear-free zone, which was characteristic of ependymoma. Immunohistochemically, the tumor cells were positive for GFAP, EMA, and CD99, but negative for S-100. A review of the cases reported in the literature shows that tanycytic ependymoma occurs more often in the spinal cord. As it can resemble pilocytic astrocytoma and schwannoma, tanycytic ependymoma should be differentially diagnosed to exclude some of the benign spindle cell tumors of the central nervous system.     

The anatomy of the brachial plexus as displayed by magnetic resonance imaging: technique and application.

Full field of view coronal chest magnetic resonance imaging (MRI) routinely displays bilateral images of the brachial plexus, surface anatomy, and anatomic structures. Eighty patients had chest radiographs correlated with surgery for thoracic outlet syndrome. The PA chest film findings correlated with the surgical findings: smaller thoracic inlet on the concave side of the cervicothoracic spine scoliosis, shorter distance between the dorsal spine of the second or third thoracic vertebral body to the concavity of the first ribs, asymmetric clavicles and coracoid processes, synchondrosis of the first and second ribs, and muscle atrophy on the side of the clinical complaints. More than 235 patients were imaged. One hundred sixty-five of these were imaged with a 1.5-T unit and 3-D reconstruction MRI. Coronal, transverse (axial), oblique transverse, and sagittal plane T1-weighted, selected T2-weighted, and fast spine echo pulse sequences were obtained, 4- to 5-mm slice thickness, 40 to 45 cm full field of view, 512 x 256 matrix and 2 NEX. Two-dimensional time of flight (2D TOF), magnetic resonance angiography (MRA) sequences were obtained in selected patients. Coronal, transverse, and sagittal sequences were reformatted for evaluation. Saline water bags were placed between the neck and thorax to enhance the signal-to-noise ratio. Compromising abnormalities of the brachial plexus were confirmed at surgery. Compromise of the neurovascular supply seemed to be one etiology that could be demonstrated. The clinical history, technique, and anatomic bilateral brachial plexus imaging is stressed to improve patient care. The cervical rib is one of the compromising brachial plexopathies selected for this presentation.     

The behavior after intravenous injection in mice of multiwalled carbon nanotube / Fe3O4 hybrid MRI contrast agents

Fe(3)O(4) nanoparticles were in situ loaded on the surface of multiwalled carbon nanotubes (MWCNTs) by a solvothermal method using diethylene glycol and diethanolamine as solvents and complexing agents. The as-prepared MWCNT/Fe(3)O(4) hybrids exhibited excellent hydrophilicity, superparamagnetic property at room temperature, and a high T(2) relaxivity of 175.5 mM(-1) s(-1) in aqueous solutions. In vitro experiments revealed that MWCNT/Fe(3)O(4) had an excellent magnetic resonance imaging (MRI) enhancement effect on cancer cells, and importantly, they displayed low cytotoxicity and neglectable hemolytic activity. After intravenous administration, the T(2)-weighted MRI signal in the liver and spleen of mice decreased significantly, suggesting the potential application of the hybrids as MRI contrast agents. The organ biodistribution studies, histological analyses and elimination investigations showed that the hybrids were uptaken by the liver, lung and spleen after intravenous injection, and could be excreted from the liver and kidney.     

Congenital arteriovenous malformation associated with progressive hydrocephalus in a newborn.

Intracranial arteriovenous malformation is rarely presented in newborns or infants. We describe an unusual case of congenital arteriovenous malformation of the brain with multiple sequestered grape-like venous sacs presented with congenital hydrocephalus. This 4-month-old girl born with a large head, presented with progressive hydrocephalus over a period of 4 months. The brain CT showed multiloculated cysts with a high-density mural nodule and thin cerebral mantle. The right lateral ventricle was collapsed by the cystic lesion, and the contralateral ventricle was markedly dilated, which was thought to be due to aqueductal obstruction by the conglomerated nidus of the arteriovenous malformation. Surgical removal of both hemispheric masses, including the overlying thin mantle. The lesion was pathologically confirmed as the arteriovenous malformation which was composed of markedly dilated veins and multiple sequestered aneurysmal sacs. The overlying cerebral tissue was dysplastic and partly infarcted. This case shows that intracerebral arteriovenous malformation is indeed a congenital anomaly and suggests that intrauterine vascular compromise can result in focal or wide maldevelopment of the brain.     

Parental punitive discipline and children’s depressive symptoms: Associations with striatal volume

Although parental harshness has been consistently linked with increased depressive symptoms in youth, its associations with children's brain structure are not well understood. The striatum has been strongly implicated in depression in adolescents and adults. In this study, we investigated the associations among parental harsh discipline, striatal volume, and depressive symptoms in children. Participants were parents and their 5- to 9-year-old children (63% female; 29% African American; 47% Hispanic/Latino). Parents completed questionnaires about their parenting behaviors and children's depressive symptoms. Children participated in a high-resolution, T1-weighted MRI scan, and volumetric data for the caudate, putamen, and nucleus accumbens were extracted (n = 20 with both parenting and MRI data; n = 48 with both MRI and depressive symptom data). Findings indicated that more frequent parental harsh discipline was significantly associated with smaller dorsal striatal volume (caudate plus putamen). In addition, smaller dorsal striatal volume was significantly associated with increased depressive symptoms in children. These associations remained significant after accounting for child age, sex, whole brain volume, and parental depressive symptoms. These findings suggest that parental harsh discipline may be associated with children's striatal volume, which may in turn be associated with their level of depressive symptoms.     

In vivo MRI of olfactory ensheathing cell grafts and regenerating axons in transplant mediated repair of the adult rat optic nerve

The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monitoring transplant-mediated repair of the adult rat visual pathway. We labelled rat olfactory ensheathing cells (OECs) using micron-sized particles of iron oxide (MPIO) and transplanted them by: i) intravitreal injection (ivit) and ii) intra-optic nerve (ON) injection (iON) in adult rats with ON crush (ONC) injury. We applied T(2)-weighted MRI and manganese-enhanced MRI (MEMRI) to visualise transplanted cells and ON axons at specific times after injury and cell engraftment. Our findings demonstrate that ivit MPIO-labelled OECs are unequivocally detected by T(2)-weighted MRI in vivo and that the T(1)-weighted 3D FLASH sequence applied for MEMRI facilitates simultaneous visualisation of Mn(2+-) enhanced regenerating retinal ganglion cell (RGC) axons and MPIO-labelled OEC grafts. Furthermore, analysis of MRI data and ultrastructural findings supports the hypothesis that iON OEC transplants mediate regeneration and remyelination of RGC axons post injury.     

磁共振在儿童椎体骨髓转化及病变中信号类型的初步研究

目的通过分析椎体骨髓磁共振信号类型分布与年龄、性别的关系,探讨正常儿童椎体骨髓转换中磁共振信号的变化规律及其在椎体病变中的应用。方法选择分析105例正常儿童的脊柱椎体磁共振T1加权序列图像,其中男性63例,女性42例,年龄3个月～17岁(平均年龄6.56岁);同时选择血液系统疾病患儿共32例作为病变组对照研究,其中男性18例,女性14例,年龄3～14岁(平均年龄8.09岁)。病种包括各种原因所致贫血(19例)和白血病(13例)。采用GE 0.2 TProfile Gold永磁型开放式磁共振扫描仪进行脊柱矢状位SE T1WI扫描。采用四级六分法对椎体T1WI表现进行分型观察,并对所获得的数据与年龄、性别的关系进行统计学处理。结果不同年龄组间脊柱椎体信号类型分布差异具有显著统计学意义(P<0.01);0～5岁儿童脊柱椎体信号类型主要为Ⅱa、Ⅲ和Ⅳa型,6～17岁儿童脊柱椎体信号类型主要为Ⅳa和Ⅳb型;脊柱椎体信号类型在不同性别间分布差异均具有显著统计学意义(P<0.01);病变组脊柱椎体表现为Ⅰ型弥漫性T1低信号者最常见(75.6%),其他常见类型还包括Ⅱa型和Ⅳa型。结论椎体磁共振T1信号表现类型的分布与年龄及性别密切相关,不同年龄、不同性别间椎体磁共振成像表现具有显著差异。同时,病变组不同年龄段患儿椎体均主要表现为弥漫性T1信号减低。因此,椎体磁共振表现分型研究有助于直观显示骨髓正常发育过程及弥漫性骨髓病变或翻转的发生。     

Feature space analysis: effects of MRI protocols.

We present a method for exploring the relationship between the image segmentation results obtained by an optimal feature space method and the MRI protocols used. The steps of the work accomplished are as follows. (1) Patients with brain tumors were imaged on a 1.5 T General Electric Signa MRI System using multiple protocols (T1 and T2-weighted fast spin-echo and FLAIR). T1-weighted images were acquired before and after gadolinium injection. (2) Image volumes were co-registered, and images of a slice through the center of the tumor were selected for processing. (3) For each patient, several image sets were defined by selecting certain MR images (e.g., 4T2's+ IT1, 4T2's+FLAIR, 2T2's+ 1T1). (4) Using each image set, the optimal feature space was generated and images were segmented into normal tissues and different tumor zones. (5) Segmentation results obtained using the different MRI sets were compared. Based on the analysis results from 27 image sets, we found that the locations of the clusters for the tumor zones and their corresponding regions in the image domain changed as a function of the MR images (MRI protocols) used. However, the segmentation results for the total lesion and normal tissues remained relatively unchanged.     

A sound sleep

Benzodiazepine is a commonly encountered agent of poisoning, which is readily diagnosed by a pertinent history of drug ingestion and the clinical scenario. In the absence of a proper drug history, the diagnosis becomes challenging. Proper clinical assessment, urine assays and imaging play a very important role in reaching the diagnosis. We present a case of acute benzodiazepine poisoning without a history of drug intake. The key pointers toward diagnosis were an unarousable state with obstructive apnea. Magnetic resonance imaging (MRI) of the brain revealed peculiar symmetrical isolated globus pallidus T2 hyperintensity. We believe this to be the first report of isolated bilateral basal ganglia T2-weighted hyperintensity in MRI in the setting of acute benzodiazepine poisoning from India.     

原发性中枢神经系统恶性淋巴瘤MR表现及其病理学基础

目的 研究原发性中枢神经系统恶性淋巴瘤(PCNSL)的MR表现及其病理学基础。方法 分析13例手术病理证实的原发性中枢神经系统恶性淋巴瘤的临床病理及MR表现。结果 13例中单发肿瘤4例，多发肿瘤9例，共计36个病灶。13例病变均累及幕上，其中8例病灶位于深部脑白质近脑室旁。肿瘤平均最大径为3．2cm。T1WI略低信号28个，T2WI等信号24个。28个病灶呈均匀强化。肿瘤水肿及占位效应相对较轻。2例PCNSL行MR动态增强扫描，早期强化均不明显，时间-信号强度曲线呈缓慢上升型。病理上肿瘤细胞弥漫分布，瘤细胞大小较一致，细胞质少，细胞核大，染色质颗粒粗，可见瘤细胞围绕血管呈袖套样浸润，少见明显的出血及片状坏死，未见钙化，病理均为非霍奇金淋巴瘤。结论 原发性中枢神经系统恶性淋巴瘤的病理基础决定其MR增强形态、占位程度以及肿瘤发生部位具有一定特征，运用不同的MR影像学检查方法和技术，在多数情况下可以做出术前正确诊断。