鼻咽癌侵犯前中颅窝的MRI表现

目的探讨鼻咽癌向前、中颅窝侵犯的ＭＲＩ征象。方法回顾分析３９例有颅神经损伤并经病理确诊的鼻咽癌病例,用１．０Ｔ磁共振机,行头颅、鼻咽部轴位和冠状面Ｔ１ＷＩ、Ｔ２ＷＩ和矢状面Ｔ２ＷＩ扫描,应用钆喷替酸葡甲胺（ＧｄＤＴＰＡ）增强后,分别行轴位、冠状面、矢状面Ｔ１ＷＩ扫描。结果（１）前颅窝受侵１３例,筛窦受侵３例,眶尖、球后受侵４例,两者同时受侵６例。（２）中颅窝受侵３８例,蝶骨体破坏３２例,蝶窦肿块２５例,破裂孔异常２０例,卵圆孔异常２８例,蝶鞍破坏６例,海绵窦受侵３５例。结论鼻咽癌经破坏颅底骨质、进出颅腔的自然骨性通道和两者并存的３种途径向前、中颅窝侵犯,ＭＲＩ能准确显示侵犯途径和程度     

Middle ear cholesteatoma extending into the petrous apex: evaluation by CT and MR imaging

CT and MR imaging findings were reviewed in four cases of acquired cholesteatoma of the middle ear that extended medially into the petrous apex and middle cranial fossa. In one case the lesion further extended anteromedially into the sphenoid sinus. CT demonstrated the lesions as nonenhancing hypodense masses with bone destruction, extending medially from the middle ear cavity to the petrous apex region. On MR imaging, the lesion was slightly hypointense relative to brain on T1-weighted images and hyperintense on T2-weighted images. MR imaging clearly delineated the extraaxial location of the lesion and associated brain displacement. The medial extension of the cholesteatomas seems to have proceeded via a detour around the bony labyrinth into the petrous apex region by following normal pathways of temporal bone pneumatization.     

Circumscribed changes in the cranium due to extracerebral fluid collection in the middle cranial fossa

On the basis of 26 cases with extracerebral fluid accumulation in the middle cranial fossa the bony changes occurring in this connection are described and discussed in respect of their aetiology. If there are bony accompanying reactions, two entities can be observed in principle. One group shows thinning and protrusion of the temporal squama, raising of the lesser wing of the sphenoid bone and protrusion of the greater wing of the sphenoid bone. The second group is associated with thickening of the temporal squama and of the lesser and greater wing of the sphenoid bone without showing any change in volume of the middle cranial fossa. If we postulate in the first group a space-occupying property of the extracerebral fluid accumulation, the prominent reactions in the second group are those usually associated with absence of pressure exercised on the cranial vault by a space-occupying growth.     

Apparent paradoxical vault changes with middle cranial fossa arachnoid cysts--implication for aetiology

Three cases of middle cranial fossa arachnoid cyst with paradoxical bone changes in the adjacent vault are described, namely, a small middle cranial fossa and pneumosinus dilatans. This association is unusual and unique. The existing literature is reviewed and the probable aetiological factors discussed.     

Central giant cell granuloma of the temporal bone.

We present two cases of central giant cell granuloma in the temporal bone. CT showed an enhancing tumor causing a smoothly margined temporal squamosa and floor of the middle fossa. External carotid angiograms showed tumor stain mainly supplied by the temporal branches of the internal maxillary artery. In one case, MR images showed a hypointense mass on both T1- and T2-weighted images that was thought to reflect the pathologic character of this lesion.     

跨中后颅窝肿瘤的CT诊断

报告30例跨中后颅窝肿瘤的CT 表现。所有肿瘤都紧邻颅底骨结构。86.6%有颅底骨质破坏,发生的部位为岩尖,斜坡,中颅窝底,鞍旁和内听道。12例瘤周无水肿,18例有轻度水肿。29例肿瘤有清楚边界。肿瘤占位表现为相邻脑组织的受压移位,脑底池变形闭塞,三、四脑室移位及脑积水。本组资料表明,岩尖和相邻的斜坡是跨中后颅窝肿瘤易侵犯的部位,破坏多见。CT 能清楚显示跨中后窝肿瘤的大小、形态和累及范围,定位准确。跨中后颅窝肿瘤多属脑外肿瘤,常见的有脑膜瘤,三叉神经瘤,听神经瘤和胆脂瘤。作者讨论了它们的CT 定性诊断和鉴别。     

三叉神经瘤的CT及MRI诊断(附27例分析)

目的提高三叉神经瘤的CT、MRI的诊断水平.材料与方法对经手术病理证实的27例三叉神经瘤行CT及MRI检查.结果颅后窝型12例,颅中窝型6例,跨颅窝型5例.位于颅中窝、颅后窝的肿瘤呈椭圆形;跨颅窝生长者呈哑铃形或不规则形.CT扫描显示稍高密度区、混合密度区、囊性低密度区,不均匀增强或环形增强.MRIT1WI呈不均匀低信号,T2WI呈不均匀高信号,肿瘤边缘清楚,有显著占位效应.结论CT、MRI定性诊断困难时,应结合临床三叉神经受损表现诊断.     

中颅窝凹陷度与颈椎张口位环枢关节显示效果的相关性研究

目的探讨中颅窝凹陷度与颈椎张口位X线片环枢关节显示效果的相关性。方法①收集标准颈椎张口位影像200例,同时照有颈椎侧位影像。②中颅窝凹陷度测量方法：在颈椎侧位影像上,连接上颌门齿下缘与枕骨下缘,测量第1、2颈椎间隙到连线的垂直距离,第1、2颈椎间隙位于连线下方的为正值,位于上方的为负值。③张口位影像评价测量方法：在标准张口位影像中,测量环枢关节颈1关节面连线中点到上颌门齿下缘的距离,连线位于上颌门齿下缘上方的为负值,相反的为正值。④评价中颅窝凹陷度测量数值与张口位影像测量数值的相关性。⑤评价中颅窝凹陷度测量数值与颈椎张口位环枢关节显示效果的相关性。结果①中颅窝凹陷度测量数值与张口位影像测量数值存在相关性。②当中颅窝凹陷度测量数值距离〉2 mm时,张口位影像环枢关节显示良好;当距离〈2 mm时,齿状突显示欠佳;而当测量数值接近0或负值时,环枢关节与上颌门齿和枕骨重叠,显示不清。结论中颅窝凹陷度对颈椎张口位影像显示效果具有相关性,当中颅窝凹陷度数值为0或负值时,张口位环枢关节与上颌门齿和枕骨重叠,显示不清。     

Infantile fibromatosis of the neck with intracranial involvement: MR and CT findings.

CT and MR imaging studies were performed in a 3-year-old boy with infantile fibromatosis arising from the infratemporal fossa and extending into the middle cranial fossa. On CT scans, the lesion was hyperattenuating (44-49 Hounsfield units [HU]), enhancing significantly after application of contrast material (63-66 HU). The MR images showed a multilobulated lesion of heterogeneous signal intensity. The tumor was markedly hypointense on T2-weighted images and slightly hypointense on T1-weighted images relative to brain tissue, iso- or slightly hyperintense relative to tongue muscle on both T2- and T1-weighted images, and enhanced strongly after administration of gadopentetate dimeglumine.     

Intracranial Aspergillus granuloma simulating meningioma on MR imaging

A case of intracranial granuloma caused by Aspergillus fumigatus involving the anterior cranial fossa is reported. The patient was nonimmuno-compromised and was asymptomatic until he had an accident. The magnetic resonance appearance simulated a meningioma, showed isointense mass with brain parenchyma on both T1- and T2-weighted images with pial vascular rim. The final diagnosis was established after surgery and histopathological examination.     

Nasopharyngeal nonossifying variant of ossifying fibromyxoid tumor: CT and MR findings.

The CT and MR findings of a nasopharyngeal nonossifying variant of an ossifying fibromyxoid tumor are presented. The findings are radiographically indistinguishable from more common malignant neoplasms encountered in this region. The tumor was isointense with muscle on T1-weighted images. On proton density- and T2-weighted images, the mass was mostly isointense with gray matter but contained some areas of lower intensity that might reflect the fibrous tissue component. The tumor eroded through the floor of the middle cranial fossa.     

CT and MRI findings of xanthoma in the orbitofrontal region

We report the imaging features of a rare case of xanthoma in the floor of the anterior cranial fossa involving the frontal bone and orbit. A 42-year-old man presented with a history of proptosis, headache, and hyperlipidemia. Computed tomography demonstrated a well-circumscribed, homogenous, expansive mass with isodensity to brain parenchyma. On magnetic resonance imaging, the tumor showed high signal intensity relative to brain white matter on T1-weighted images, with heterogeneously high signal intensity on T2-weighted images. Histological examination established a diagnosis of xanthoma.     

MR imaging of the nasopharynx and floor of the middle cranial fossa. Part I. Normal anatomy

The normal anatomy of the nasopharynx and floor of the middle cranial fossa was analyzed with magnetic resonance (MR) imaging. MR images from five healthy volunteers were correlated with whole-organ cryomicrotome sections from three cadavers. Anatomic connections exist between the paranasopharyngeal spaces and the surface structures of the skull base. These anatomic connections include the intimate relationship between the eustachian tube and the pharyngobasilar fascia, the attachment of the muscles of mastication and deglutition to the skull base, and vascular and nervous structures in the foramina. The inherent contrast between the soft tissues of the nasopharynx and related structures and the bone of the floor of the middle cranial fossa allowed excellent visualization of these anatomic connections.     

3T MR三维稳态进动快速成像序列显示脑池段颅神经及其与周围病变的关系

目的探讨3T MR三维稳态进动快速成像(3D-FIESTA)序列显示中、后颅窝颅神经及其与周围病变关系的价值。方法对34例颅内脑外病变的患者行反转恢复SE T1WI、FSE T2WI及3D-FIESTA序列扫描。脑池段颅神经与周围病变的关系情况与手术结果相对照。结果 34例患者中共48处病变,3D-FIESTA序列显示9条神经被周围病变包绕,51条颅神经被压迫,与病变相邻的颅神经有10条,病变累及其邻近25条神经;其中23例患者行手术治疗,手术与MR图像对照,3D-FIESTA显示颅神经与周围病变关系的准确性分别为5/6、26/28、3/3、12/13。结论 3T MR 3D-FI-ESTA序列可以正确显示脑池段颅神经及其与周围病变的关系,对治疗前评估及病变的治疗有重要的应用价值。     

颞下窝原发肿瘤的CT及MR表现

目的：探讨颞下窝原发肿瘤CT及MRI表现。方法回顾性分析20例经病理证实的颞下窝原发肿瘤的CT及MR资料。结果颞下窝肿瘤形态多不规则。神经鞘瘤多边界清楚（5/6）,MR T1WI为等信号,T2WI为高信号肿物伴线状分隔样低信号,2例通过卵圆孔伸入中颅窝呈哑铃状生长。恶性外周神经鞘膜肿瘤边界多不清楚（4/5）,MR T1WI为等信号,T2WI为不均匀高信号,病变可侵犯邻近肌肉及骨质。横纹肌肉瘤MR T1WI为等信号,T2WI为高信号。孤立性纤维性肿瘤边界清楚,MR T1 WI等信号,T2 WI为混杂略高信号,增强后较明显强化。腺样囊性癌边界不清,沿神经浸润生长。侵袭性多形性腺瘤MR T1 WI为等、低信号,T2 WI为高信号,侵犯邻近肌肉。淋巴瘤形态不规则,边界清楚,MR T1WI为低信号,T2WI为中高信号,轻度强化,内有线样血管影穿行。结论熟悉颞下窝原发肿瘤CT及MRI表现,有助于提高该部位病变诊断及鉴别诊断水平。     

Facial nerve neuromas: CT findings

Although neuromas of the facial nerve are rare, they present with uniform clinical and radiological findings. Their pluridirectional tomography findings have been well described; however, the appearance of the intracranial extension of the neuroma which is best visualized by CT has not been emphasized. We report five cases of facial nerve neuromas with particular attention to their intracranial extension. For comparative purposes we also have reviewed 10 cases of acoustic and eight cases of trigeminal neuromas, all involving the cerebellopontine angle (CPA) and the middle cranial fossa. Two of the five facial nerve neuromas affected the second and third segments of the facial canal, and three involved both the CPA and the middle cranial fossa spreading across the midpetrosal bone. This type of tumor extension seems to be characteristic of facial nerve neuromas. In acoustic and trigeminal neuromas the tumor crossing toward the middle fossa takes place via the tentorial hiatus (acoustic) and the petrous apex (trigeminal).     

颅内血管外皮细胞瘤的MRI及CT诊断

目的:探讨颅内血管外皮细胞瘤的MRI及CT影像学特点,以提高诊断水平。材料和方法:回顾性分析经手术病理证实的颅内血管外皮细胞瘤4例。4例均行MRI扫描,其中2例并行CT扫描。结果:4例血管外皮细胞瘤分别位于前、中颅窝、右侧桥小脑角区及右顶部各1例,均呈明显分叶状。T1WI示肿瘤呈高或等、低混杂信号,T2WI示肿瘤呈等或等、高混杂信号。增强扫描示肿瘤实性部分高度增强,其中4例肿瘤周边均可见不同程度水肿带,3例见流空血管影,1例肿块内见坏死囊变灶、1例邻近颅骨骨质破坏,1例见幕上轻度脑积水。CT平扫示肿瘤呈高密度,未见瘤内钙化、邻近颅骨骨质增生及脑膜尾征等脑膜瘤常见征象。结论:MRI及CT表现对颅内血管外皮细胞瘤的诊断有一定的作用,最终诊断依靠病理。     

Facial nerve neurinoma presenting as middle cranial fossa mass: CT appearance

Two cases of large seventh nerve neurinoma presenting as masses in the middle cranial fossa are presented. The radiographic findings are discussed with attention to CT appearance. In the appropriate clinical context, correlation with radiographic studies should strongly support diagnosis of middle fossa neurinoma originating from the seventh cranial nerve. Failure of preoperative diagnosis may result in unexpected operative loss of facial nerve function.     

Giant cell reparative granuloma of the cranial vault.

We describe a case of giant cell reparative granuloma in the cranial vault, which is an extremely rare location for this entity. CT scans showed an enhancing skull tumor with no surrounding sclerosis in the frontal bone. MR images showed a mass isointense with gray matter on both T1- and T2-weighted images.     

Gadolinium-enhanced MR of the postoperative internal auditory canal following acoustic neuroma resection via the middle fossa approach.

PURPOSE: To evaluate the ability of gadolinium-enhanced MR in detecting recurrent tumor in patients whose acoustic neuromas were surgically removed via the middle cranial fossa approach. PATIENTS AND METHODS: Postoperative gadolinium-enhanced exams of 13 of 44 patients who underwent excision of acoustic neuromas via the middle cranial fossa approach were reviewed. RESULTS: Postoperative enhancement was seen in 12 of the 13 patients; two patients underwent serial exams without significant change. On the basis of a single exam, we were unable to conclusively differentiate postoperative enhancement from residual or recurrent tumor. CONCLUSIONS: A single exam is of limited value. Serial studies are recommended to identify changes that would indicate tumor growth. A proposed MR follow-up schedule is an initial baseline exam within 2 months of surgery and a repeat exam during the second postoperative year.