MR imaging of neurocysticercosis

Twenty-six patients with neurocysticercosis were studied with MR imaging to correlate their clinical presentation with the location and appearance of their neurocysticercosis lesions. Intraventricular cysts were present in 14 patients (54%), parenchymal cysts were present in 18 (69%), and intraventricular together with parenchymal cysts were present in six (23%). Intraventricular cysts were detected by mass effect, ventricular obstruction, detection of a cyst rim, and/or CSF flow void adjacent to the cyst. The intensity of most intraventricular and parenchymal cysts presumed to be viable was similar to that of CSF on both T1- and T2-weighted sequences. Cysts presumed to be degenerated had increased signal intensity on T1-weighted images, probably resulting from increased protein content. Pericystic high signal intensity surrounding lesions of various ages was seen on both proton-density- and T2-weighted images and represents gliosis, edema, and inflammation. Patients with parenchymal cysts had symptoms of seizures, while those with intraventricular cysts generally had symptoms related to obstructive hydrocephalus. Aqueductal stenosis, seen in 10 patients (38%), was possibly due to ependymal inflammation or adhesions caused by prior ventricular infection by neurocysticercosis. One patient with the racemose form of neurocysticercosis demonstrated abundant cyst wall proliferation resulting in obstructive hydrocephalus. In six patients scanned 1-6 months after oral praziquantel therapy, there was no change in the MR appearance of intraventricular cysts, while some parenchymal cysts showed evidence of degeneration. We found MR to be useful in detecting the cysts of neurocysticercosis and the accompanying signs of cyst degeneration and pericystic inflammation. MR was inferior to CT in the detection of parenchymal calcifications.     

Intraventricular noncolloid neuroepithelial cysts

Symptomatic intraventricular developmental cysts of neuroepithelial origin occurring in the lateral and fourth ventricles are extremely rare. We report the clinical, radiologic, and computed tomographic (CT) findings in three such cases, two occurring in the lateral ventricles and one in the fourth ventricle. Within lateral ventricles, these cysts are distinguished from colloid cysts by their large size, more posterior locations, and CSF-equivalent CT attenuation of their contents. Lack of contrast enhancement on CT and angiographic avascularity are also features. Fenestration in two cases and partial cyst excision in the third case relieved the predominant symptoms. The symptomatology and theories of histogenesis are reviewed and the differential diagnosis discussed.     

MR imaging of neurocysticercosis

Magnetic resonance (MR) was performed in 50 patients with neurocysticercosis. Comparison was made with other neuroradiological imaging modalities including CT, myelography, CT ventriculography, and CT myelocisternography. Eighteen patients were found to have intraventricular cysts. In several patients, these were multiple and 22 intraventricular cysts were discovered. Although 4 of the 22 ventricular cysts were missed by MR, T1-weighted images can play a significant role in the early detection of intraventricular cysticercosis cysts, showing the cyst wall (9 of 22), a high intensity mural nodule (6 of 22), and increased signal intensity of the cyst fluid (5 of 22). Cisternal cysts (14 cysts in 10 patients) could be identified; they appear similar to intraventricular cysts, but mural nodules are infrequently seen (1 of 14). Twenty-nine patients had 69 parenchymal cysts. An attempt was made to assess the viability of these parenchymal lesions by matching the CT and MR findings with the Escobar pathologic staging system. Neuroimaging findings seemed compatible with early parenchymal lesions in the vesicular stage in 11 instances. Findings in cases with later stage cysts tend to support the concept that a dying larva provokes pronounced inflammatory reaction in the adjacent brain. Computed tomography remains the superior modality for depicting parenchymal calcifications within dead larvae. A case of a spinal cysticercosis cyst demonstrated with MR (in a patient with extensive intracranial cisternal cysts and a fourth ventricular cyst) is described.     

中枢神经系统神经上皮囊肿MRI特征及其病理基础

目的 探讨神经上皮囊肿(NEC)的MRI表现特征及其病理基础.资料与方法 回顾性分析15例术前经MRI检查并经手术病理证实的NEC患者的MRI资料,并和蛛网膜囊肿、皮样囊肿、表皮样囊肿及低级别胶质瘤进行对照分析,结合病理重点研究NEC的发生部位、信号特征、强化方式、囊肿周围有无水肿等情况.结果 15例NEC中6例位于侧脑室后角及三角区,2例位于脑实质内,1例位于左侧桥小脑角池,3例位于骶管内,3例为脉络膜裂囊肿.MRI确诊率达80%,误诊率为20%.位于脑室、脑池、骶管内者及脉络膜裂囊肿,囊壁菲薄,无壁结节,增强扫描无强化,误诊率低,但有时需与蛛网膜囊肿鉴别;2例位于脑实质内者周围无水肿,增强扫描无强化,但囊内信号复杂,误诊率高,常需与血肿及肿瘤性病变鉴别.结论 NEC最常见于侧脑室三角区,其MRI表现有典型特征;而位于脑实质内的NEC罕见,其MRI表现多样,无特征性.     

Improved detection of intraventricular cysticercal cysts with the use of three-dimensional constructive interference in steady state MR sequences

BACKGROUND AND PURPOSE: Before the advent of MR imaging, intraventricular cysts were difficult to diagnose noninvasively. Among the invasive procedures used were contrast ventriculography and CT ventriculography. MR imaging, with its multiplanar imaging capabilities, excellent depiction of tissue contrast, and versatile parameters, is an important tool in the assessment of intraventricular cystic lesions. We investigated the role of three-dimensional constructive interference in steady state (3D-CISS) MR sequences in the evaluation of intraventricular cysticercal cysts. METHODS: The study group comprised 11 patients with intraventricular cysticercal cysts. MR studies included spin-echo (SE) T1-weighted, turbo-SE T2-weighted, and 3D-CISS sequences. All images were obtained on a superconducting 1.5-T MR unit. The routine and 3D-CISS sequences were reviewed and interpreted separately by two neuroradiologists. RESULTS: All patients underwent surgery for excision of intraventricular cysticercal cysts. Eight patients had cysts in the fourth ventricle, two in the lateral ventricle, and one in the third ventricle. SE T1-weighted images showed the cystic wall in nine cases, the scolex in four, and the cystic fluid in two. Turbo-SE T2-weighted images showed the cystic wall and scolex in three and four cases, respectively. The routine sequences did not show the scolex, cystic wall, or cystic fluid together in any of the 11 patients. 3D-CISS images showed the scolex in all 11 patients and the cystic wall and cystic fluid in eight patients each. In seven of the 11 patients, 3D-CISS images showed the scolex, cystic wall, and fluid together. CONCLUSION: The 3D-CISS sequence is more sensitive and specific than routine SE sequences in the diagnosis of intraventricular cysticercal cysts.     

Large asymptomatic noncolloid neuroepithelial cysts in the lateral ventricle: CT and MR features

Summary Two cases of large asymptomatic cysts of the lateral ventricle are presented. The cyst walls or cyst contours were demonstrated well by proton density-weighted or T2-weighted spin echo images. These cysts are being detected as incidental findings in increasing frequency with the increasing use of MR imaging. Our data and review of the literature suggest that surgical intervention is not necessarily warranted, but that careful clinical evaluation is indicated. The diagnostic problem of intraventricular cysts is also discussed.     

脉络膜裂影像学表现及脉络膜裂神经上皮囊肿的诊断

目的探讨脉络膜裂的影像学表现和脉络膜裂神经上皮囊肿的影像表现,提高其鉴别诊断水平。方法结合文献和颅脑大体标本,对照研究正常脉络膜裂在MR上的影像学表现,并对14例脉络膜裂神经上皮囊肿进行CT和MR I分析。结果MR可清楚地显示脉络膜裂全长,表现为含脑脊液裂隙。脉络膜裂神经上皮囊肿表现为圆形或椭圆形、边界光滑锐利的脑脊液样低密度或信号,增强扫描无强化,近期随访囊肿无明显变化。结论认识脉络膜裂影像学表现和脉络膜裂神经上皮囊肿的CT和MR I表现,有利于正确诊断,减少误诊。     

MR ventriculography for the study of CSF flow

BACKGROUND AND PURPOSE: Various MR techniques have been used to assess CSF flow and to image the subarachnoid spaces and ventricles. Anecdotal reports describe the use of intrathecal and intraventricular gadolinium-based contrast agents in humans and animals. We sought to determine the clinical usefulness of gadolinium-enhanced MR ventriculography for assessing CSF flow in patients with various neurologic conditions. METHODS: Five patients (three female and two male patients aged 6 months to 65 years) were included in the study. After performing sagittal, coronal, and axial T1-weighted MR imaging of the brain, 0.02-0.04 mmol of gadodiamide was injected into the lateral ventricle. Sagittal, coronal, and axial T1-weighted imaging was repeated soon after the injection. We were specifically looking for the site of obstruction to CSF flow in those patients with hydrocephalus, communication between cysts and ventricles, elucidation of suspicious intraventricular lesions, and patency of third ventriculostomies. RESULTS: MR ventriculography showed good delineation of the ventricular system in all patients. In one patient with carcinomatosis and hydrocephalus, a block to contrast material flow was detected at the right foramen of Luschka. In another patient with hydrocephalus, partial block to the flow of contrast material was demonstrated at the right foramen of Monro. In a patient with hydrocephalus and a posterior fossa cyst, flow of contrast material was blocked between the third ventricle and the cyst, with a thin streak of contrast material in the aqueduct. As an assessment of the patency of a third ventriculostomy, MR ventriculography showed flow of contrast material into the suprasellar cisterns from the third ventricle in one patient and absence of flow in another. CONCLUSION: MR ventriculography is a safe technique for assessing CSF flow, with application in determining the site of obstruction in hydrocephalus, in assessing communication between cysts and the ventricle, and in determining the functioning status of endoscopic third ventriculostomies.     

Sub-callus epidermoid cyst. A case report

The cranio-encephalic epidermoid cysts are rare tumors. These lesions are extra-axial and can occur at the infratentorial or supratentorial level. The epidermoid cysts are classically in contact with the base of the skull, and less often intraventricular; the other locations are exceptional. Because of their CT aspect (hypodense lesion, rarely isodense, well defined, without contrast enhancement, and without surrounding edema) and MR aspect (in more than 70% of the cases: more or less homogeneous lesion, hypointense in T1 and hyperintense in T2), the authors believe that it is possible to suggest such a diagnosis even with an atypically located case. We report the case of an epidermoid cyst located between the corpus callosum and the falx cerebri.     

Imaging of meniscal cyst of the knee in three cases

Three cases of solitary meniscal cyst in the knee have recently been diagnosed in our departments using ultrasound and nuclear magnetic resonance (MRI). Two cysts involved the lateral and one the medial meniscus. The appearance of these lesions on ultrasound and MR images is shown. All three cysts had low intensity on T1-weighted images and high intensity on T2-weighted images and clearly communicated with a large horizontal tear in the meniscus. Ultrasonography showed a relatively hypoechoic lesion and, in the two cases of lateral meniscal cyst, focal areas of relatively increased echoes which are probably due to meniscal debris. Ultrasound showed the abnormal meniscus in both of these cases. MRI is the best way of showing the cyst and an accompanying meniscal tear but, where MRI is not available, ultrasound may be an easy and inexpensive way of making a diagnosis whether or not it is used in conjunction with positive contrast arthrography.     

MR imaging of epithelial cysts of the oral and maxillofacial region

The aim of the present study was to review the magnetic resonance (MR) appearance of primary epithelial cysts in order to distinguish the cysts from other possible lesions. MR images were obtained in 27 cases of epithelial cysts, including 7 odontogenic keratocysts, 3 dentigerous cysts, 1 glandular odontogenic cyst, 10 radicular cysts, 4 nasopalatine duct cysts, and 2 nasolabial cysts. In addition, contrast enhanced MR imagings were performed in 12 cases, including 3 odontogenic keratocysts, 1 dentigerous cyst, 1 glandular odontogenic cyst, and 7 radicular cysts. We obtained the following results on the basis of the above MR and contrast enhanced MR findings. (a) Odontogenic keratocysts had a predilection for intermediate-high signal intensity (SI) on T1-weighted images (WI) and heterogeneous low-high SI on T2WI. (b) Dentigerous cysts, glandular odontogenic cyst, radicular cysts and nasolabial cysts showed the same predilection with the SI, which were homogeneous intermediate SI on T1WI and homogeneous high SI on T2WI. (c) The MR images of the nasopalatine duct cysts, which showed homogeneous high SI on T1WI, were specific. (d) The Gd-T1WI would be useful in decisively differentiating odontogenic cysts, which showed rim-enhancement, from tumors consisting of solid components. In conclusion, we were able to obtain more information from the MR and contrast enhanced MR images than from conventional radiograph findings.     

骶管内脊膜囊肿的MR诊断

目的　探讨骶管内脊膜囊肿的临床表现、MR诊断及鉴别诊断。方法　 2 5例骶管内脊膜囊肿 ,均经手术病理证实。其中男 9例 ,女 16例 ,年龄 18～ 56岁 ,平均 40 .3岁。所有病例均行MR检查。结果　囊肿位于骶管内 ,呈卵圆形 19例 ,长条状囊袋形 3例 ,不规则形 1例 ,串珠形 2例。囊肿境界清楚 ,囊壁菲薄 ,囊液信号与脑脊液信号相似 ,T1WI囊液呈均质性低信号 ,T2 WI囊液呈高信号 ,8例T2 WI囊液信号较脑脊液信号更高。其中 7例囊肿内于T1WI和T2 WI可见细条状神经根影。 8例增强扫描囊液、囊壁无增强。结论　MR是骶管内脊膜囊肿最佳的检查方法之一 ,正确认识其MR征象不仅能够准确诊断 ,而且可以指导临床治疗方案的选择。     

MR imaging and MR arthrography of paraglenoid labral cysts

OBJECTIVE: We investigated the pathophysiology of paraglenoid labral cysts on the basis of MR imaging, MR arthrography, and cyst aspiration. MATERIALS AND METHODS: From 2211 MR imaging examinations, 51 (2.3%) cysts in 46 patients were identified. MR arthrography (n = 5), cystography (n = 1), arthroscopy (n = 17), percutaneous needle aspiration (n = 4), and medical records were also reviewed (n = 46). RESULTS: On MR imaging and arthrography, cysts were best viewed on T2-weighted images. Mean cyst diameter and volume were 2.2 cm and 2.8 cm3, respectively. Fifty-seven percent of cysts were located adjacent to the posterior labrum. On MR imaging and arthroscopy, a labral tear was identified in 27 (53%) and 15 (88%) patients, respectively. Eight cysts that caused compression neuropathy were large (mean size, 3.1 cm; p = 0.04) and located next to the posterior or inferior labrum. In four of five patients, MR arthrograms showed no intraarticular contrast material in the cyst. Cystograms showed no communication with the glenohumeral joint space, and cyst aspiration resulted in temporary symptom relief; however, cysts recurred in three of four patients. CONCLUSION: Most paralabral cysts are associated with labral tears. Paralabral cysts may be difficult to identify on MR arthrography unless a T2-weighted sequence is performed. Direct communication between a cyst and joint space rarely occurs. A posterior or inferior cyst may cause compression neuropathy of the suprascapular or axillary nerve, respectively. Cyst aspiration may result in temporary relief of symptoms, but an untreated labral tear should be suspected if cysts recur.     

Neuroepithelial (colloid) cysts. Pathogenesis and unusual features.

A brief history of the theories of pathogenesis of the origin of neuroepithelial cysts is presented. An origin more diffuse than the paraphysis seems most likely in our opinion, and we attempt to substantiate this theory with several of the cases from our series. One posterior third ventricular neuroepithelial cyst and one in the fourth ventricle are demonstrated roentgenographically. Also included in our series are a case showing suprasellar calcification on plain skull roentgenograms, not previously reported in neuroepithelial cysts, and a case with a cyst measuring 9 cm, the largest neuroepithelial cyst yet reported.     

Posterior fossa epithelial cyst: case report and review of the literature.

A 49-year old woman with progressive cranial nerve signs and hemiparesis was found at MR imaging and at surgery to have a cyst at the foramen magnum. Immunohistochemistry and electron microscopy showed an epithelial cyst of endodermal origin. MR findings were of an extraaxial mass, with short T1 and T2 times. Unless immunohistochemistry and electron microscopy are used in the final diagnosis of such cysts, all posterior fossa cysts lined by a single layer of epithelium should be described simply as epithelial cysts.     

Imaging findings of central nervous system neuroepithelial cysts

Neuroepithelial cysts are rare and mostly asymptomatic cerebrospinal fluid (CSF)-like cysts. We describe herein the imaging findings in five patients with neuroepithelial cysts. Two cases of proven and three of presumed neuroepithelial cysts are presented. Three of five are located in the thalamus, a location which is not characteristic for neuroepithelial cysts. In the case of incidental finding of asymptomatic neuroepithelial cyst, clinical and radiological follow-up is indicated and surgical intervention is not necessarily warranted. Received 9 June 1997; Revision received 20 August 1997; Accepted 6 October 1997     

CSF pulsations within nonneoplastic spinal cord cysts

Because of its sensitivity to fluid motion, MR imaging was used to investigate fluid dynamics in syringomyelia. Three major findings characterized syringomyelia: pulsatile fluid in cysts, nonpulsatile fluid in cysts, and damaged cord tissue. The fluid in preoperative syrinx cavities pulsated in a fashion similar to subarachnoid CSF. Pulsation was more prominent in large cysts but was also seen in small cysts. Nonpulsatile cysts were generally of smaller diameter, were shorter in length, and often were single; they could, however, coexist with pulsatile cysts. Nonpulsatile cysts had etiologies similar to those of pulsatile cysts: Chiari malformation, trauma, and unknown. Damaged cord, characterized by abnormal high signal on T2-weighted sequences, was seen in 15 of 16 patients and could be either focal or diffuse but was always adjacent to syrinx cavities. Postsurgical MR scans had a lower incidence of pulsatile cysts. In five patients with both pre- and postoperative MR scans, shunting of the cyst reduced the size of the pulsating cyst (two patients) or reduced the size of the cyst and eliminated pulsation altogether (three patients). Axial, T2-weighted images are recommended in the investigation of spinal cord cysts to determine the presence or absence of pulsatile fluid. The presence of pulsation indicates a nonneoplastic cyst. The absence or reduction of CSF pulsation may prove to be a valuable indicator of the success of a shunting procedure.     

Neuroradiology of central neurocytoma

Summary Central neurocytomas (CN) are rare, usually benign cerebral intraventricular neuroepithelial tumors, which occur in adult patients. Retrospective evaluation of the CT- and MRI-findings in eight cases as well as review of the cases reported in the literature showed that CN usually presents as a primarily slightly hyperdense and/or hyperintense mass within the body of the lateral ventricle with moderate contrast enhancement. The majority of tumors contain both multiple small cysts and calcifications and exhibit a characteristic broad based attachment to the superolateral ventricular wall. We conclude that these criteria appear to be reliable to exclude other intraventricular tumors such as astrocytoma, giant cell astrocytoma, ependymoma, subependymoma, intraventricular oligodendroglioma and meningioma. Preoperative diagnosis of CN may prove of value for planning therapy, because this tumor type seems to have a better prognosis than other intraventricular tumors.     

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     

MR imaging findings of Rathke's cleft cysts: significance of intracystic nodules

BACKGROUND AND PURPOSE: Rathke's cleft cysts often may be difficult to differentiate from other intrasellar or suprasellar masses on radiologic studies. The purpose of this study was to describe the significance of intracystic nodules, a diagnostic characteristic found in Rathke's cleft cysts, on MR images. METHODS: A retrospective review of MR studies was conducted for 13 patients who, after pathologic analysis, were diagnosed as having Rathke's cleft cyst. These patients underwent unenhanced and contrast-enhanced T1- and T2-weighted axial and coronal spin-echo sequential imaging. The signal intensity and incidence of the intracystic nodules on T1- and T2-weighted images were analyzed. The signal intensity of the nodule was compared with that of white matter and surrounding cyst fluid. The signal intensity of cyst fluid was compared with the intraoperative appearance of the cyst fluid. Biochemical and pathologic analyses of the intracystic nodules were conducted in two cases. RESULTS: An intracystic nodule having high signal intensity on T1-weighted images and low signal intensity on T2-weighted images was observed in 10 (77%) of the cases. At surgery, intracystic nodules were yellow, waxy, solid masses. Pathologic analysis showed this nodule to be a mucin clump. Biochemical analysis of the intracystic nodules showed cholesterol and proteins as the main constituents. In the Rathke's cleft cyst with intracystic nodules, cyst fluid revealed low signal intensity to isointensity relative to the intensity of the nodules on T1-weighted images, and isointensity to high signal intensity on T2-weighted images. Intracystic nodules were clearly visible on T2-weighted images. CONCLUSION: Because cyst fluid of Rathke's cleft cysts shows variable intensities on MR images, the specific diagnosis is often difficult when based on MR signal intensity values alone. The presence of an intracystic nodule with characteristic signal intensities on MR images may be indicative of the diagnosis of Rathke's cleft cyst.