Why should we report posterior fossa emissary veins?

Posterior fossa emissary veins are valveless veins that pass through cranial apertures. They participate in extracranial venous drainage of the posterior fossa dural sinuses. The mastoid emissary vein, condylar veins, occipital emissary vein, and petrosquamosal sinus are the major posterior fossa emissary veins. We believe that posterior fossa emissary veins can be detected by radiologists before surgery with a thorough understanding of their anatomy. Describing them using temporal bone computed tomography (CT), CT angiography, and cerebral magnetic resonance (MR) venography examinations results in more detailed and accurate preoperative radiological interpretation and has clinical importance. This pictorial essay reviews the anatomy of the major and clinically relevant posterior fossa emissary veins using high-resolution CT, CT angiography, and MR venography images and discusses the clinical importance of reporting these vascular variants.Posterior fossa emissary veins pass through cranial apertures and participate in extracranial venous drainage of the posterior fossa dural sinuses. These emissary veins are usually small and asymptomatic in healthy people. They protect the brain from increases in intracranial pressure in patients with lesions of the neck or skull base and obstructed internal jugular veins (1). They also help to cool venous blood circulating through cephalic structures (2). Emissary veins may be enlarged in patients with high-flow vascular malformations or severe hypoplasia or aplasia of the jugular veins. They are associated with craniofacial syndromes (1, 3). Dilated emissary veins may cause tinnitus (4, 5).We aim to emphasize the importance of reporting posterior fossa emissary veins prior to surgeries that are related to the posterior fossa and mastoid region. Here, we review their embryology and anatomy based on high-resolution computed tomography (CT), CT angiography, and magnetic resonance (MR) venography images.     

后颅窝脑实质出血穿入脑室系统的CT研究

目的：探讨后颅窝出血经脑室系统弥散的CT表现及临床意义。方法：回顾性分析23例后颅窝出血的CT检查资料。结果：后颅窝出血经脑室系统弥散者12例,其中第四脑室积血12例,第三脑室积血9例,侧脑室积血8例。后颅窝出血穿入脑室与血肿体积有明显关系（P＜0．01）,第三脑室扩大在脑室积血与非积血者之间有显著差异（P＜0．01）。结论：后颅窝出血可穿入第四脑室并经脑室系统弥散。CT检查对于发现病因及制定治疗方案具有重要意义。     

Posterior cranial fossa dural arteriovenous malformation with a varix mimicking a thrombosed aneurysm: case report

Summary Dural arteriovenous malformations (AVMs) in the posterior cranial fossa are relatively infrequent. Intradural haemorrhage is one of their specific complications. Angiographic demonstration of varices or aneurysmal structures is one of the hallmarks of severe cases. We report a patient with posterior cranial fossa dural AVM associated with a varix mimicking a thrombosed aneurysm on CT and MRI. Internal carotid and vertebral angiography failed to demonstrate an aneurysm, but external carotid injection revealed a dural AVM affecting the sigmoid sinus, and a varix. The AVM was completely eliminated by embolization. When a dural AVM is suspected clinically selctive angiography should be performed to confirm the diagnosis even when CT or MRI do not show dilated vessels.     

MR imaging of the spine in children

MR imaging was reviewed in 66 pediatric spinal cord patients with diagnoses of posterior fossa tumor (n = 8), primary spinal cord tumor (n = 3), metastatic disease (n = 11), neuroectodermal disorder (n = 8), congenital malformation (n = 14), trauma (n = 2), and demyelinating, neurodegenerative, or metabolic disorders (n = 9). MR proved to be useful in delineating the extent of posterior fossa and cord tumor including metastasis to the cord. MR was of limited value in demyelinating and metabolic disorders. Arnold Chiari malformations, syringomyelia, tethered cord and meningoceles were all easily evaluated using MR.     

后颅窝囊肿的CT－MR影像学

目的：本文目的是对后颅窝囊肿的ＣＴ－ＭＲ影像学的诊断作用进行评价。材料与方法：１２例后颅窝囊肿的ＣＴ和ＭＲ影像表现进行了分析，探讨了其与临床表现和类型的相关性。结果：本组病例包含Ｄａｎｄｙ－Ｗａｌｋｅｒ囊肿（５例）、蛛网膜囊肿（３例）和巨枕大池（４例），ＣＴ和ＭＲ都可提供无创性检测手段。结论：ＣＴ和ＭＲ二者对后颅窝囊肿的诊断均有效，但在显示病变的性状、大小和轮廓方面，ＭＲ比ＣＴ稍胜一筹     

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。     

Imaging findings in intracranial aspergillosis

RATIONALE AND OBJECTIVES: The authors' purpose was to elucidate the various computed tomographic (CT) and magnetic resonance (MR) imaging findings in intracranial aspergillosis. MATERIALS AND METHODS: Retrospective analysis of cranial imaging findings was performed in eight proved cases of central nervous system aspergillosis. The patients ranged in age from 17 to 75 years. Four patients were immunocompromised, and four were immunocompetent. CT was performed in all eight patients, and MR imaging in five. RESULTS: Six patients (75%) had multiple lesions seen on the imaging studies, with a total of 27 focal brain lesions demonstrated. The lesions were most commonly seen in the cerebral hemispheres (n = 21), with lesser involvement of the basal ganglia (n = 2) and the posterior fossa (n = 4). Seven lesions were hemorrhagic on CT and/or MR images. There was a correlation between lesion size and hemorrhage, with hemorrhage more likely in larger lesions (>15 mm). At pathologic examination, foci of hemorrhage were noted within both infarcts and abscesses. Enhancement was noted in five lesions, four of which were confirmed abscesses. Contrast enhancement of the lesions was vague and week in immunocompromised patients but solid and strong in immunocompetent patients. There were 18 lesions without hemorrhage or enhancement; they were either infarcts or abscesses at pathologic examination. Some of these small nonhemorrhagic nonenhancing brain lesions in the subcortical white matter mimicked lacunar infarcts. CONCLUSION: Typical imaging findings of intracranial aspergillosis include multifocal lesions involving the cerebral hemispheres, with hemorrhage in approximately 25% of lesions. Lesional contrast enhancement tends to be stronger in immunocompetent hosts.     

Magnetic resonance imaging of intracranial epidermoids: report of two cases

Intracranial epidermoids are uncommon benign tumors in the subarachnoid spaces. We have studied two patients with these tumors originating in the basal cisterns using magnetic resonance (MR) imaging, computed tomography (CT), and cerebral angiography. Both CT and MR showed the extraaxial position of these tumors and their extension into the posterior fossa well. Angiography did not show any abnormal vasculature but displacement of vessels by the tumor mass was well demonstrated. MR was found to be relatively specific in characterizing these tumors.     

MR cisternography: initial experience in 41 cases.

PURPOSETo present our initial experience with MR cisternography, an application of fast spin-echo MR with fat suppression, and compare it with routine MR cranial studies in the evaluation of the subarachnoid cisterns and their contents.METHODSMR cisternography is a heavily T2-weighted fast spin-echo technique with high spatial resolution; it uses fat suppression and video reversal of the images. A small number of individual sections (two to four) are compressed into a composite image by a maximum-intensity projection algorithm, providing better depiction of anatomy in three dimensions. MR cisternography enhances the signal intensity of the cerebrospinal fluid (CSF) with suppression and subtraction of the background. A total of 41 patients were examined during a period of 6 months. MR cisternography was performed as an additional one (n = 31) or two (n = 10) sequences after conventional MR study.RESULTSTwenty-one cases of disease were examined by MR cisternography, including 8 neoplasms, 4 CSF fistulas, and 3 large intracranial aneurysms. MR cisternography provided information unavailable by conventional MR studies in 17 cases. These included visualization of fistulous tracks in patients with CSF rhinorrhea, origin of a large suprasellar aneurysm, an additional loculus of a posterior fossa aneurysm and its relation to surrounding structures, and proper location of three tumors (intraaxial versus extraaxial). Clear depiction of the pituitary gland separate from the cavernous sinus was noted in 60% of the cases, and a new observation of a CSF sleeve around the third nerve in the posterior cavernous sinus was made in 85% of the cases.CONCLUSIONMR cisternography is superior to conventional MR studies in depicting anatomic structures within the subarachnoid spaces. This technique is recommended in the evaluation of cranial CSF fistulas and suprasellar and posterior fossa masses and in diagnosis of intraaxial versus extraaxial location of intracranial tumors.     

儿童后颅凹肿瘤的CT, MRI诊断

目的：分析儿童后颅凹常见肿瘤的ＣＴ和ＭＲＩ影像学表现,提高诊断该病的准确性。材料和方法：收集儿童后颅凹常见肿瘤４０例,其中髓母细胞瘤１８例,星形细胞瘤１３例,室管膜瘤９例。行ＣＴ和ＭＲＩ检查。ＣＴ平扫４０例,增强扫描３２例;ＭＲＩ平扫２８例,增强扫描１６例。将其结果与手术病理对照。结果：４０例儿童后颅凹常见肿瘤ＣＴ显示率为９７５％,ＭＲＩ显示率为１００％。术前ＣＴ定性误诊１１例,准确率为７２５％。术前ＭＲＩ定性误诊４例,准确率为８５７％。ＣＴ和ＭＲＩ联合检查,能对后颅凹多数常见肿瘤作出定位及定性诊断。ＭＲＩ能多方位成像,去除后颅凹颅骨伪影的干扰,对该病的定位定性诊断明显优于ＣＴ。结论：ＣＴ和ＭＲＩ检查相结合,能提高诊断儿童后颅凹常见肿瘤的准确率,为临床提供更准确的诊疗信息。     

Imaging in acute basilar artery thrombosis

The aim of this study was to review the imaging features in acute (<24 h) basilar artery thrombosis. CT and MR studies in 11 patients with clinical diagnosis of acute basilar artery thrombosis were retrospectively reviewed. MR angiography was obtained in 4 patients. Correlation with clinical symptoms was performed. Multiple cranial nerve palsies and hemiparesis were the most common clincal symptoms at presentation. CT revealed hyperdense basilar arteries (n=7) and hypodensities in the posterior circulation territory (n=8). In one instance, the infarction was hemorrhagic. MR imaging showed absence of flow void within the basilar in 6 patients and MRA (using both PC and TOF techniques) confirmed absence of blood flow in 4 basilar arteries. One week after presentation, 5 patients died. Autopsy was obtained in 1 case and confirmed the diagnosis of basilar artery thrombosis. Basilar artery thrombosis has fairly typical imaging features by both CT and MR. MRA may be used to confirm the diagnosis. Prompt recognition may lead to early thrombolytic treatment and may improve survival.     

Low-grade adenocarcinoma of probable endolymphatic sac origin: CT and MR appearance.

The CT and MR appearance of a case of low-grade adenocarcinoma of probable endolymphatic sac origin is presented. The tumor destroyed a large part of the posterior temporal bone and showed prominent extension into the posterior cranial fossa.     

Comparison of MR imaging, CT, and angiography in the evaluation of the enlarged cavernous sinus

Twenty-one patients with enlargement of the cavernous sinus were studied with CT and MR imaging. Eighteen of the patients also had cerebral angiography. MR was superior to CT in differentiating parasellar aneurysms from neoplastic masses. MR was also superior to both CT and angiography in defining the relationships of cavernous sinus neoplasms to the internal carotid artery, pituitary gland, optic chiasm, infundibulum, and fifth cranial nerves. Only in the definition of bone erosion or hyperostosis was MR inferior to another method (CT). We conclude that MR should be the initial diagnostic study in patients with symptoms of a parasellar mass, with supplementation when necessary by CT and angiography.     

Significance of CT and MR findings in sphenoid sinus disease

Disorders of the paranasal sinuses, particularly the sphenoid sinus, can be associated with significant disorders of the optic and other cranial nerves. We examined 100 consecutive routine CT scans, 100 posterior fossa CT scans, and 100 MR scans to look for evidence of sinus disease, especially of the sphenoid sinus. The sphenoid sinus was abnormal in 7% of scans by all methods. Other sinuses were more frequently abnormal, including maxillary (23%), ethmoid (34%), and frontal (16%). Although MR was more sensitive in detecting sinus inflammation in the ethmoid and maxillary sinuses, the frequency of visible sphenoid sinus abnormalities detected by MR was not significantly greater when compared with CT. Of those patients with abnormal sphenoid sinuses, 24% had visual problems associated with the abnormality.     

血管母细胞瘤的影像学诊断

目的探讨血管母细胞瘤的影像学诊断价值。资料与方法搜集经手术病理证实的中枢神经系统血管母细胞瘤36例;回顾性分析CT和MRI表现。结果病变位于后颅凹27例,大脑半球3例,脊髓8例;其中2例为小脑内多发病变,2例为小脑及颈髓并存病变。CT表现为囊性病变边缘有软组织密度结节,MRI表现为囊性信号伴边缘灰色信号结节,可见周围流空的血管信号影,结节明显强化;脊髓病变以血管信号影为主。结论CT和MRI对向管母细朐瘤均有串付串件诊断价值．MRI优于CT扫描。     

颅内血管病变CTA综合评价

目的探讨颅脑CT血管造影(CTA)和综合后处理技术的临床应用。资料与方法对30例临床诊断或疑诊颅内血管病变患者和4例血管畸形栓塞术后患者行CTA检查，并分别完成5种图像后处理：多层面重建(MPR)、表面遮盖三维显示(3D—SSD)、容积显示(VR)、薄层块最大强度投影(TS-MIP)和仿真内镜(VE)观察。结果CTA详细显示颈内动脉瘤10例，前后交通支动脉瘤5例，椎动脉瘤3例，颈内动脉海绵窦瘘1例，颅内动脉迂曲延长症1例，栓塞治疗后4例，其余10例正常。各种病理情况的CTA后处理以VR最优，综合显示更佳。结论颅脑CTA显示血管病变优越，以VR为主的综合后处理显示最好。     

MR Imaging of Orbital Inflammatory Pseudotumors with Extraorbital Extension

Objective

To demonstrate a variety of MR imaging findings of orbital inflammatory pseudotumors with extraorbital extension.

Materials and Methods

We retrospectively reviewed the MR features of five patients, who were diagnosed clinically and radiologically as having an orbital inflammatory pseudotumor with extraorbital extension.

Results

The types of orbital pseudotumors were a mass in the orbital apex (n = 3), diffuse form (n = 2), and myositis (n = 1). The extraorbital extension of the orbital pseudotumor passed through the superior orbital fissure in all cases, through the inferior orbital fissure in two cases, and through the optic canal in one case. The orbital lesions extended into the following areas: the cavernous sinus (n = 4), the middle cranial fossa (n = 4), Meckel''s cave (n = 2), the petrous apex (n = 2), the clivus (n = 2), the pterygopalatine fossa and infratemporal fossa (n = 2), the foramen rotundum (n = 1), the paranasal sinus (n = 1), and the infraorbital foramen (n = 1). On MR imaging, the lesions appeared as an isosignal intensity with gray matter on the T1-weighted images, as a low signal intensity on the T2-weighted images and showed a marked enhancement on the post-gadolinium-diethylene triamine pentaacetic acid (post-Gd-DTPA) T1-sequences. The symptoms of all of the patients improved when they were given high doses of steroids. Three of the five patients experienced a recurrence.

Conclusion

MR imaging is useful for demonstrating the presence of a variety of extraorbital extensions of orbital inflammatory pseudotumors.     

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.     

Cerebellar infarct caused by spontaneous thrombosis of a developmental venous anomaly of the posterior fossa

Spontaneous thrombosis of a posterior fossa developmental venous anomaly (DVA) caused a nonhemorrhagic cerebellar infarct in a 31-year-old man who also harbored a midbrain cavernous angioma. DVA thrombosis was well depicted on CT and MR studies and was proved at angiography by the demonstration of an endoluminal clot.     

Neurovascular contact of the brain stem in hypertensive and normotensive subjects: MR findings and clinical significance

BACKGROUND AND PURPOSE: About 20 years ago, a theory was put forward that neurovascular contact of the root entry zone (REZ) of the ninth and 10th cranial nerve is responsible for elevated blood pressure in patients with essential hypertension. To test this hypothesis, we used MR tomography and MR angiography to evaluate the presence and degree of neurovascular contact of the REZ of the ninth and 10th cranial nerves in patients with essential hypertension as compared with patients with renal parenchymal hypertension and normotensive healthy volunteers. METHODS: Patients with essential hypertension (group 1; n = 33), renal parenchymal hypertension (group 2; n = 30), and normotensive healthy volunteers (group 3; n = 25) underwent high-resolution (axial and coronal) brain stem MR imaging and MR angiography. The images were interpreted consensually by two radiologists who were blinded to the patients' hypertensive status. Neurovascular contact was graded as vessel contact without associated brain stem deformity (grade I), vessel contact with associated brain stem deformity (grade II), or vessel contact with associated deformity and displacement of the brain stem (grade III). RESULTS: Neurovascular contact of the REZ of the ninth and 10th cranial nerve on the left side was found in 48.5% in group 1, in 26.7% in group 2, and in 48.0% in group 3. The rate of neurovascular contact on the right side was 24.2%, 13.3%, and 40.0%, respectively. chi(2) analysis showed no statistical difference between the groups. CONCLUSION: Neurovascular contact is not more frequent in patients with essential hypertension than in normotensive control subjects or in those with secondary hypertension; therefore, MR imaging cannot aid patient selection for neurosurgical vascular decompression.