儿童颅内转移性肿瘤的CT特点

目的：分析儿童颅内转移性肿瘤的ＣＴ特点。材料和方法：１６例颅内转移的原发灶中颅外神经母细胞瘤６例、颅内生殖细胞瘤４例、髓母细胞瘤２例、白血病２例、淋巴瘤１例和脑干肿瘤１例。１５例中原发灶或／和转移灶经组织学证实，仅１例脑干肿瘤及其转移为ＣＴ诊断。原发肿瘤诊断年龄从２至１３岁，平均８．７岁，从原发肿瘤诊断至发现转移的间隔时间从０至４２个月，平均１３．１个月。结果：柔脑膜转移在１６例中有１０例，占６２．５％：脑实质转移８／１６，占５０％：硬膜外转移４／１６，占２５％。结论：ＣＴ对各种类型颅内转移的诊断是有价值的。与成人相比，儿童脑外转移（硬膜外转移和柔脑膜转移１４／１６，占８７．５％）明显多于脑内转移（８／１６，占５０％），脑内转移主要是由柔脑膜转移而不是血行转移发展而来。     

幕上脑实质室管膜瘤CT和MR诊断

目的：分析幕上脑实质室管膜瘤ＣＴ和ＭＲ影像学特点。材料与方法：２４例经手术病理证实的幕上脑实质室管膜瘤，行ＣＴ和（或）ＭＲ检查；男１６例，女８例；１０岁以下９例，１１～２０岁６例，２０岁以上９例。结果：部分囊性型２１例，好发于顶叶，肿瘤部分为囊性，实质较少，囊液在ＣＴ平扫时稍高于脑脊液密度，ＭＲＴ１加权像信号稍高于脑脊液，Ｔ２加权像似脑脊液高信号。肿瘤实质在ＣＴ平扫时呈稍高密度或等密度，ＭＲＴ１加权像信号稍低于脑实质，ＭＲＴ２加权像似灰质信号或稍高于灰质信号。实质内常有条状或点状钙化。瘤周一般无水肿或仅有轻度水肿，增强扫描肿瘤实质及囊壁轻到中度强化。完全实质型多见于年长的成人，肿瘤好发于额叶，且常累及双侧，ＣＴ平扫时肿瘤多呈稍高密度，出血和钙化多见，瘤周水肿明显，多呈显著不均质强化。结论：幕上脑实质室管膜瘤可分为部分囊性型和完全实质型，部分囊性型ＣＴ和ＭＲ表现很有特点，常能提供准确诊断，完全实质型与胶质瘤鉴别困难。     

儿童天幕下肿瘤的CT影像诊断

儿童期颅脑肿瘤发病率仅次于自血病，居第二位，而颅后窝肿瘤与幕上肿瘤的发病率基本接近。较常见的儿童颅后窝肿瘤是髓母细胞瘤，星形细胞瘤，室管膜瘤等。虽然髓母细胞瘤．室管膜瘤、非典型畸胎样瘤可以表现为脑室内肿瘤，但是它们起源于小脑实质，因此，将它们归类为脑实质内肿瘤。脑实质外肿瘤包括神经鞘瘤、胚胎性肿瘤如皮样囊肿、表皮样囊肿、肠源性囊肿等。儿童天幕下肿瘤按部位又可分为中线区肿瘤和小脑半球、小脑表面区肿瘤二大类。前者自前向后依次起源于脑干，第四脑室、小脑局部及枕大池周围，共同特点为引起中脑导水管狭窄或阻碍，第四脑室扩大或缩小，前移或后移，很少或轻度左右移位，幕上脑积水。中线区肿瘤多见于儿童和青少年。     

小脑蚓部肿瘤的CT诊断(附95例分析)

目的：提高小脑蚓部各肿瘤ＣＴ诊断的正确性。材料与方法：９５例经手术,病理证帝物小脑蚓部肿瘤,男性５９例,女性３６例,术前均行ＣＴ平扫及增强扫描。结果：成神经管细胞瘤４１例,ＣＴ平扫以略高、等或略低混杂密度米,增强后肿瘤可均匀或不均匀强化。星形胶质瘤２９例,ＣＴ平扫以略低、低混杂密度米,增强后可轻度、不规则强化。致这膜瘤１０例,平扫以等、混合密度为主,增强多有均匀强化,常伴脑积水。或血管细胞瘤９例,     

侵袭性纤维瘤病的CT诊断

目的：对侵袭性纤维瘤病的腹壁外组及腹壁组作比较，重点讨论腹壁外侵袭性纤维瘤病的ＣＴ表现。材料和方法：对４０例４３个经手术及病理证实的侵袭性纤维瘤病术前行ＣＴ检查，肿瘤位于腹壁外２９个，腹壁１４个。结果：腹壁外肿瘤比较特征性的ＣＴ征象为肿块较大，肿瘤呈爪样浸润正常肌肉组织，平扫病灶密度均匀。增强后强化，表现为密度大部分均匀呈等或高密度，偏中心数个低密度改变，或密度不均匀，小梁状、条索状改变；或肿瘤均匀等密度。腹壁肿瘤则较小，平扫与增强密度都均匀。ＣＴ还能帮助评价肿瘤的侵袭范围以及与周围结构的关系。结论：提高对腹壁及腹壁外侵袭性纤维瘤病的ＣＴ表现的认识，有助于术前定性诊断。     

脑内畸胎瘤的 CT 诊断

脑内畸胎瘤的ＣＴ诊断平学军刘娜嘉刘闽生秦△脑内畸胎瘤是颅内少见的先天性肿瘤。ＣＴ检查能区分瘤体内不同组织成分的密度，具有很高的定性诊断价值。现报告经手术病理证实的５例脑内畸胎瘤，结合文献复习，分析ＣＴ表现，并加以讨论。１材料与方法１．１本组５例，男性...     

幕上室管膜瘤的CT诊断

目的：提高幕上室管膜瘤ＣＴ诊断的正确性。材料与方法：回顾分析３９例经手术病理证实为幕上室管膜瘤的ＣＴ表现，肿瘤位于脑实质内１９例，脑室内１６例，脑室内外多发瘤灶者４例。结果：脑实质内室管膜瘤典型表现为脑室旁，尤其是侧脑室三角区或前角旁等或混杂密度较大肿块，常伴有囊变和斑点状钙化，肿瘤与脑室壁关系密切。幕上脑室内室管膜瘤常位于侧脑室体部，大多数（７３．３％）瘤内有钙化。恶性室管膜瘤多数（６８．４％）位于脑实质内，囊变常见，强化明显。脑室内外多发瘤灶者提示恶性室管膜瘤。结论：提高对幕上室管膜瘤典型ＣＴ表现的认识，有助于术前定性诊断。     

单发脑转移瘤的CT与MRI特征

本文探讨了单发脑转移瘤ＣＴ与ＭＲⅠ的特征。７１例患者均经手术病理或临床证实，其中６６例ＣＴ检查，８例ＭＲⅠ检查。单发脑转移瘤的ＣＴ表现可分为以下４型：（１）肿瘤环并肿瘤水肿型，其ＣＴ特征是肿瘤环外厚里薄征（８７％）、坏外壁光滑规整（７１％）、环内壁不光滑（７７％）；（２）肿瘤结节并肿瘤水肿型；（３）单纯肿瘤结节型；（４）单纯肿瘤水肿型。平扫ＭＲⅠ特征是肿瘤结节与环不清楚或大清楚的肿瘤水肿。     

肝癌CT“密度更低区”对栓塞治疗后碘油潴留形态的影响

作者对４０例经ＬＰ－ＨＡＥ的原发性肝癌，进行了栓后ＣＴ肿瘤边缘部碘油的潴留形态与栓前ＣＴ肿瘤边级部密度状态的对照研究，结果说明：肝瘤栓前ＣＴ肿瘤边缘部出现的“密度更低区”，是导致栓后碘油不潴留或不潴留的主要原因。文中还对肝癌“密度更低区”的病理基础进行了讨论。     

高原脑水肿的CT表现及其病理基础的实验研究

目的：研究高原脑水肿的颅脑ＣＴ表现及其病理学基础。方法：采用低压缺氧模型在模拟７０００ｍ海拔高度条件下观察家猫缺氧２４小时、４８小时和７２小时的颅脑ＸＴ表现和病理变化。结果；缺氧２４小时～７２小时内ＣＴ表现和病理变化与缺氧持续时间无明显关系。３０只动物扣２２只ＸＴ表现为脑室脑池变小或消失，服沟变窄，大脑、基底节、脑干和小脑的密度不同程度地普遍增高，病理变化主要微血管扩张、大脑皮层神经细胞肿用生、细     

The role of computed tomography in the diagnosis of brain tumors in infants and children

Summary CT has considerably facilitated the diagnosis of intracranial tumors, especially in infants and children. The authors review their experience with a series of 260 children with proven brain tumors. In most cases CT is so conclusive that other diagnostic techniques are no longer often needed. Pneumoencephalography in particular has largely been replaced by CT in recent years in the authors' departments, and the frequency of central ventriculography with contrast material has decreased substantially. Particular diagnostic difficulties with regard to tumors near to or within the caudal brain stem, some posterior fossa tumors, small vermian tumors, and tumors of the cerebral hemispheres are discussed.     

Tumoren der hinteren Schädelgrube

Various types of brain tumor can occur in the region of the posterior fossa. Brain metastases in adults are the most common malignancies at this localization. Ependymomas, medulloblastomas and pilocytic astrocytomas occur mostly in children and only rarely in adults. Other tumors that occur in the posterior fossa are meningiomas, schwannomas, hemangioblastomas, brain stem gliomas and epidermoid tumors. Due to the fact that the various tumors of the posterior fossa have different treatment approaches and prognoses, an accurate and specific diagnosis is mandatory. This review discusses the imaging aspects by computed tomography (CT) and magnetic resonance imaging (MRI) of the most frequent tumors of the posterior fossa.     

Primary meningeal tumors in children: correlation of clinical and CT findings with histologic type and prognosis.

PURPOSE: To identify the radiologic features that might help in preoperative differentiation of the meningiomas from the remaining primary meningeal tumors, in particular the malignant tumors. METHODS: The clinical and computed tomographic features of 21 children with histologically proved primary meningeal tumors were analyzed. FINDINGS: Benign tumors (meningiomas) are more likely to occur in older children, to have longer symptom duration, and to have CT appearances similar to the "typical" adult meningioma. Atypical CT features suggest a malignant meningeal tumor, such as meningeal sarcoma, melanoma, or meningeal primitive neuroectodermal tumor. The recent identification of a new subtype of meningioma (a "sclerosing" group) is discussed. This is common in children and the CT and clinical features are similar to those seen in other meningiomas. It is frequently mistaken histologically for an intraaxial tumor, or for an atypical or malignant meningioma. These sclerosing meningiomas may also show brain invasion but despite this, in the short term, the prognosis is no different from other meningiomas. CONCLUSION: The bad reputation previously ascribed to childhood primary meningeal tumors should be confined to that small group that are malignant. Meningiomas have a more favorable outlook.     

儿童脑肿瘤的MRI表现(附60例分析)

目的：探讨儿童脑肿瘤的MRI特点，以期提高其诊断水平。方法：回顾分析经手术病理证实的60例儿童脑肿瘤MRI表现，并与病理结果进行对照。结果：60例中，发生于脑干17例(28．3％)，鞍内及鞍上区15例(25％)，小脑13例(21．6％)，幕上半球8例(13．3％)，间脑侧脑室、四脑室各2例，枕骨1例。大多数肿瘤在T1WI上表现为低信号、等信号或／和低信号，在T2WI上为不均匀高信号，增强扫描表现为均匀或不均匀强化。结论：胶质瘤是儿童期脑肿瘤最常见的肿瘤，脑干是其最常发生的部位，其次是颅咽管瘤，常发生于鞍内及鞍上区，小脑是儿童髓母细胞瘤常发生的部位。     

MR imaging of brain stem gliomas

Magnetic resonance (MR) and CT examinations of 26 patients with the established or clinically suspected diagnosis of brain stem glioma were reviewed. Eleven tumors were seen on both MR and CT. The entire extent of the abnormality was better outlined on MR, although CT was more advantageous in demonstrating cystic components and calcium deposition. Magnetic resonance and CT depicted focal intratumoral hemorrhage equally. Magnetic resonance was found to be particularly suitable to follow up the progression or regression of the disease. Of particular interest were two patients with evidence of aqueductal obstruction but normal CT appearance of the midbrain; the causative abnormality, believed to be a glioma, was clearly shown by MR imaging. In nine patients the normal appearance was helpful to exclude the possibility of a brain stem glioma. Thus far, results have shown 100% sensitivity (true positive ratio) and specificity (true negative ratio) with MR in the evaluation of brain stem gliomas. It is concluded that MR imaging should be the examination of choice and could be the definitive screening procedure in patients with suspected brain stem glioma.     

Resistive NMR of brain stem gliomas

Summary The NMR and CT findings in 22 patients with primary brain stem tumors were compared to determine the value of each study in identifying, and delineating the extent and relationships of the tumor to brain anatomy. NMR was found to be distinctly superior to CT in showing involvement of the medulla and upper cervical cord. NMR eliminates the need for intrathecal enhanced metrizamide CT, and in the future should be the only initial diagnostic test needed for the evaluation of intrinsic brain stem tumors.     

Neuroradiological findings of relatively rare tumors of the brain

In the publication by the World Health Organization of the histological classification of central nervous system tumors in 1993, several new tumor types were added, including pleomorphic xanthoastrocytoma (PXA), dysembryo-plastic neuroepithelial tumor (DNT), and desmoplastic infantile ganglioglioma (DIG). Referring to these newly classified tumors of the brain, the present article describes the neuroradiological findings of relatively rare tumors of the brain such as PXA, subependymoma, gangliocytoma, dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease), DIG, central neurocytoma (CN), neuroblastoma, desmoplastic medulloblastoma, atypical teratoid/rhabdoid tumor (ATRT), glossopharyngeal schwannoma, and malignant fibrous histiocytoma (MFH). PXA and DIG affect the cerebral hemisphere and appear to be cystic masses with a solid component on CT and MRI. Gangliocytomas commonly occur in the floor of the third ventricle and the temporal lobe. CT and MRI typically show a mass lesion with no vasogenic edema. In Lhermitte-Duclos disease, T2-weighted MR images reveal characteristic enlarged folia. Desmoplastic medulloblastomas tend to favor the cerebral hemisphere in the adolescent. ATRTs are rarely seen in infants or children and resemble medulloblastomas or primitive neuroectodermal tumors. Intracranial MFHs are also rare tumors and sometimes resemble the meningiomas.     

Brain stem tumors

The most common brain stem tumor in both the adult and pediatric population is the brain stem glioma. MR has significant advantages over CT in detecting the presence of the tumor as well as evaluating its extent. Diagnosis must be as precise as possible, since therapy is generally administered without biopsy material available for pathologic examination. Defining the extent of the tumor is mandatory so that appropriate radiation therapy margins are available and geometric misses do not occur. Unenhanced CT may yield some prognostic information regarding patients who have brain stem gliomas. Further work must be done to determine if any MR correlates, such as calculated T1- or T2-relaxation times, can provide similar information. Also, work relating to any prognostic information provided by the appearance of gadolinium enhancement should be undertaken. With MR, the ability to differentiate brain stem glioma from other posterior fossa tumors and from benign lesions that often do not require therapy now exists.     

Intrakranielle Tumoren im Kindesalter

Every year, 400 children suffer from a brain tumor. These are the most frequent solid tumors in the pediatric patient. They represent a very heterogenic group of tumors with different clinical symptoms, pathology, therapy and prognosis. Imaging modalities such as CT and MRI are important for the diagnosis and follow-up after therapy. Brain tumors in children are responsible for 15-20% of all brain tumors. Tumors of the central nervous system are the second most common tumors after leukemia. Infra- and supratentorial tumors occur in equal number, however, there are differences in the age of occurrence: supratentorial tumors occur more often within the first 2-3 years of life, whereas infratentorial tumors reach there peak between 4 and 10 years. After the tenth year, infra- and supratentorial tumors occur with equal frequency.     

Sonography of brain tumors in infants

Cranial sonograms of six children with brain tumors (one newborn, four infants, and one 4-year-old child) are presented. In four, sonography showed a large tumor mass and displacement of adjacent structures. In two, the tumors were demonstrated as areas of abnormal brain parenchymal echogenicity without obvious mass effect. Two of the tumors were diffusely echogenic, one was primarily cystic, and three were of mixed echogenicity. Areas of cystic degeneration and calcification within the tumors were well demonstrated. Correlation was made with cranial computed tomography (CT) in all patients; in each case sonography accurately demonstrated the location and extent of the tumor. Since sonography is used as a screening procedure in infants with a large head or an abnormal neurologic examination, sonography may be the first examination to demonstrate the tumor mass. However, since the sonographic features are not specific for neoplasms, further clarification of the process by CT should be recommended.