CT and MRI findings of intraosseous schwannoma of the mandible: a case report

We report the radiographical findings of a rare case of intraosseous schwannoma of the mandible. The tumour that presented as a unilocular, well-defined, radiolucent lesion on plain radiography was located in the molar region. On CT, the tumour was a well-demarcated mass with no periosteal reaction and no destruction of the bone cortex. Destructive changes in the cortical wall of the mandibular canal by the tumour were observed on CT, but no evidence of dilatation and shift in the inferior mandibular canal was seen. MR imaging revealed that the mandibular canal was encased by the tumour as a solid mass without cystic parts. The signal intensity of the tumour was non-specific on MRI. Characteristics of intraosseous schwannoma in the mandible are the encasement of the canal by a well-demarcated tumour without periosteal reaction and the destruction of mandibular bone cortex. The destructive change of the inferior mandibular canal can be observed on CT and MRI. However, a biopsy is necessary to make the final diagnosis because of the non-specificity of the findings.     

翼腭窝神经鞘瘤的CT和MRI诊断

目的 分析翼腭窝神经鞘瘤的CT和MRI表现. 资料与方法 回顾性分析12例经组织学证实的翼腭窝神经鞘瘤的影像学资料. 结果 12例神经鞘瘤均为单侧发病,病变以翼腭窝为中心生长并向其通道及周围间隙蔓延,边界清楚,呈卵圆形8例,梭形4例.CT表现:翼腭窝扩大,相应骨质受压变薄、移位及吸收;平扫显示10例病变密度均匀,另2例病变内可见低密度区,5例行CT增强扫描,其中3例病变显示不均匀强化.MRI表现:与脑实质比较,T1WI均呈等信号;T2WI呈等信号9例,高信号3例,10例病灶内可见点、片状高信号,其中5例并可见结节状高信号;增强后不均匀强化,T2WI上所见的高信号区均未见明显强化,其他区域中度或显著强化. 结论 根据典型的骨质及信号改变,可提示本病诊断.     

CT, MRI, and PET findings of gastric schwannoma

Gastric schwannoma is a rare tumor that accounts for only 0.2?% of all gastric tumors. We report a case of gastric schwannoma that underwent computed tomography (CT), magnetic resonance imaging (MRI), and [(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET), and its histological confirmation was acquired. Gastric schwannoma showed high intensity on T2-weighted and diffusion-weighted MRI and high maximum standardized uptake on [(18)F]-FDG-PET. Lymphadenopathy close to the tumor was also found. Although diffusion-weighted MRI, [(18)F]-FDG-PET, and the presence of lymphadenopathy could suggest malignant tumors, the detail interpretation of the other CT and MRI findings may give a clue for the diagnosis of gastric schwannoma.     

舌下神经鞘瘤的CT和MRI表现及其病理基础(附4例报告)

目的 研究舌下神经鞘瘤的CT、MRI特征性表现。方法 回顾分析了4例经手术病理证实的舌下神经鞘瘤CT和MRI表现。结果 从病变部位看，右侧3例，左侧1例；颅内段2例，颅内与颅外段同时受累2例。CT表现：舌下神经孔扩大和骨质破坏，并见软组织块影2例。MRI表现：舌下神经径路上出现圆形、椭圆形的软组织块影4例，T1WI为等信号，T2WI为等信号和高信号；有明显的强化。结论 舌下神经径路上出现软组织块影是其特点；MRI对舌下神经鞘瘤的诊断优于CT，特别是MRI增强扫描。     

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.     

Plexiform schwannoma of the foot

The present report describes a plexiform schwannoma involving the subcutis of the foot in an 8-year-old boy. Gross findings revealed thin fibrous septa in a multilobulated tumor that was partly separated into free body-like nodules in the subcutis. Preoperative CT and MRI failed to delineate this multinodular architecture or free bodies. This is a case presentation including the CT and MR findings associated with plexiform schwannoma. Received: 17 September 1998; Revision received: 7 December 1998; Accepted: 9 December 1998     

鼻腔鼻窦神经鞘瘤的CT和MRI表现

目的 探讨鼻腔鼻窦神经鞘瘤的CT和MRI表现,并评价2种影像检查方法的临床应用价值.方法 回顾性分析12例经组织学证实鼻腔鼻窦神经鞘瘤的影像资料,12例均做cT检查,10例做MR检查.结果 12例神经鞘瘤中良性11例,低度恶性1例;发生于鼻筛区4例,上颌窦3例,上颌窦、筛窦及蝶窦2例,上颌窦、鼻腔1例,蝶窦1例,后鼻孔1例;病变边界清楚,呈椭圆形4例,不规则形8例.CT表现:病变区轮廓扩大,相应鼻腔鼻窦骨质受压、变薄、移位,其中8例伴局部吸收,1例伴轻微侵蚀性破坏;平扫病变密度均匀10例,另2例其内可见低密度区,增强后2例病变显示不均匀强化.MRI表现:与脑实质比较,T1WI呈等信号,其中3例可见片状及结节状低信号,2例伴有片状高信号;T2WI呈不均匀等信号7例,稍高信号3例,其中2例伴有片状低信号;9例病变内可见点、片状高信号,其中6例伴有规整的结节状高信号,1例显示液-液面;增强后9例显示中度或显著不均匀强化,1例较均匀显著强化.2例行MR动态增强扫描,时间.信号强度曲线为平台型.6例伴有阻塞性鼻窦炎,T1WI为低信号,T2WI为高信号,增强后其内部不强化,边缘可见线状强化.MRI均清楚显示病变的范围和伴发的炎症.结论 骨质变形、变薄、吸收和MR T2WI所示斑片、结节状高信号并且增强后无强化为该病特征性表现;CT和MR两种影像检查方法联合使用能够对该病的诊断、治疗提供更全面的信息.     

面神经瘤的影像学研究

目的：研究面神经瘤的影像学检查方法和影像学表现,提高诊断准确性。方法：10例经手术病理证实的面神经瘤均行CT检查,6例还进行MR平扫和增强扫描。回顾性分析CT表现和MRI表现,并比较CT和MRI的优缺点。结果：10例面神经瘤中6例面神经鞘瘤和4例面神经纤维瘤,8例累及面神经水平段,6例累及膝部,4例累及乳突段,2例累及迷路段,3例累及内听道段,2例累及腮腺段,1例累及脑池段。主要CT表现：面神经管扩大9例;鼓室内软组织影7例;听小骨破坏5例;乳突蜂房内软组织肿块4例。主要MRI表现：6例均表现面神经增粗,其中2例显示鼓室内=乳突内和颈静脉窝软组织肿块,2例显示鼓室内软组织肿块;3例肿块呈略长T1、略长T2信号,信号不均匀,增强后呈不均匀强化;3例肿块与面神经呈等信号,信号均匀,呈均匀强化;2例面神经瘤累及内听道段面神经,平扫未显示,增强后呈明显强化而显示。比较CT与MRI表现后,发现2例累及面神经内听道段者MRI显示而CT未显示,1例累及面神经鼓室段起始部者MRI亦显示而CT未显示;对于较小的面神经瘤,MRI能直接显示增粗的面神经本身,而CT仅显示面神经管扩大和（或）破坏。结论：CT和MRI,尤其是MR增强扫描能很好地显示面神经瘤的形态、部位、范围和内部结构,有助于定位诊断和定性诊断,为临床制订手术方案和确定手术入路提供依据。     

Computed tomography evaluation of pelvic organ prolapse. Techniques and applications

OBJECTIVES: Pelvic organ prolapse is a common debilitating condition affecting women. Cross-sectional imaging with magnetic resonance imaging (MRI) depicts pelvic floor anatomy as well as organ prolapse and can complement or replace fluoroscopy. Occasionally, patients cannot tolerate MRI, but multiplanar visualization of pelvic floor soft tissue anatomy and organ prolapse is clinically desired. The objective of this study was to determine if computed tomography (CT) is a potential diagnostic technique in these specific situations for demonstrating organ prolapse and the pelvic floor. METHODS: Seven women (mean age: 63.5 years) with clinical pelvic organ prolapse were referred for CT of the pelvis from the gynecologic and surgical clinics from November 1998 to September 2001. The CT technique included the following: insufflation of rectal air, positive oral contrast, supine position with knees flexed, and imaging at rest and straining with a single-detector scan in 5 cases (slice thickness of 3 mm, table speed of 5 mm/s, 2-mm reconstruction interval) and a multidetector scan in 1 case (detector collimation of 1 mm, slice thickness of 1.25 mm, 1-mm reconstruction interval). Axial and 3-dimensional images were interpreted. RESULTS: Computed tomography demonstrated prolapse in 5 of 7 patients. At CT, cystocele was present in 2 of 7 patients, vault or cervical prolapse was present in 4 of 7, enterocele was present in 3 of 7, rectocele was present in 2 of 7, and levator abnormalities were present in 4 of 7. Surgery was performed in 3 of the 5 patients with positive CT findings, and prolapse was confirmed. Surgery was also performed in 1 patient with negative CT findings, and global prolapse was detected. CONCLUSIONS: Demonstration of pelvic organ prolapse and muscular pelvic floor abnormalities is feasible with CT if the patient strains adequately. In patients who cannot tolerate MRI, CT may be useful as an alternative diagnostic tool.     

颈外侧部肿块的影像学诊断与鉴别诊断

目的 分析各种颈外侧部肿块增强扫描前后的CT、MRI表现.资料与方法 回顾性分析45例经病理证实的颈外侧部肿块增强扫描前后的CT、MRI表现,包括病灶的部位、大小、形态、边缘、密度、信号、强化特点及其与邻近血管和间隙的关系.结果 45例颈外侧部肿块中,鳃裂囊肿6例,淋巴管瘤6例,淋巴结结核6例,淋巴结转移瘤8例,颈动脉体瘤3例,淋巴瘤2例,淋巴结炎4例,神经鞘瘤5例,颈部脓肿、巨大淋巴结增生、神经纤维瘤,原始神经外胚层肿瘤、海绵状血管瘤各1例.鳃裂囊肿、淋巴管瘤表现为囊性无强化;颈部脓肿表现为环形强化;淋巴结结核、淋巴结转移瘤表现为结节状轻中度强化与环形强化共存;淋巴瘤、淋巴结炎、巨大淋巴结增生、神经纤维瘤、神经鞘瘤、原始神经外胚层肿瘤呈轻中度强化;海绵状血管瘤、颈动脉体瘤呈高度强化.结论 颈外侧部肿块增强前后CT、MRI表现有特征性改变,可作出较为准确的诊断.     

Neuroradiological findings of intracranial schwannomas not arising from the stems of cranial nerves

Four cases of intracranial schwannomas not arising from the stems of cranial nerves are reported. All cases were confirmed by surgery and pathological examination. The related histogenesis and the CT and MRI findings are discussed, and the literature is reviewed. The CT and MRI findings of these tumours were analysed retrospectively and their pathological characteristics were reviewed. The tumours presented as heterogeneous hypointense to isointense mixed dense lesions with multiple areas of cystic degeneration and necrosis. Extensive cystic degeneration was the prominent characteristic on CT. The tumours showed hypointense to isointense signal on T(1) weighted images and heterogeneous hyperintense signal on T(2) weighted images. On contrast enhanced CT and MRI, the solid component and the wall of the tumours showed moderate to strong enhancement. Haematoxylin and eosin staining of the lesion demonstrated two histological patterns, Antoni type A and Antoni type B. Immunostaining showed intense immunoreactivity for S-100 protein. The CT and MRI findings of these tumours were similar to those of schwannomas arising from cranial nerves, although the former show a higher rate of cystic degeneration. Therefore, even when a mass is not in the usual cranial nerve region, if its imaging characteristics are similar to those of common schwannomas, the possibility of a schwannoma not arising from cranial nerve should be considered.     

面神经瘤的CT和MRI诊断

目的：研究面神经瘤的CT和MRI表现,提高对其的认识。方法：9例面神经瘤中,8例面神经鞘瘤,1例面神经纤维瘤。7例行颞骨高分辨CT扫描,2例常规扫描;6例行MRI检查,其中5例做了增强扫描。结果：本组发生在右侧5例,左侧4例;内听道1例,迷路段4例,膝状神经节6例,鼓突段（降段）6例,茎乳孔5例,腮腺3例。CT表现：面神经管扩大,膝状窝骨壁膨胀,面神经径路上有条索状或结节样软组织影。MRI表现：面神经呈结节样或条索状增粗,呈跨节段性分布,T1WI为等信号,T2WI为等或高信号;有明显强化。结论：面神经径路上出现实质性节段性肿块是面神经瘤的影像特点。MR增强扫描是一种有效的检查手段。     

不典型神经鞘瘤的影像学诊断

目的 探讨不典型神经鞘瘤的临床影像学表现特点。方法 回顾分析44例经病理学诊断的不典型神经鞘瘤的CT和MRI表现。结果 CT表现为类圆形或分叶状低密度或等低混杂密度灶,绝大多数（38/40）边界清楚,其中实性肿瘤17例,囊实性病灶19例,单纯囊性病灶4例。CT增强扫描肿瘤实质呈渐进性不均匀强化。囊性病灶内存在强化程度不一的结节灶可能是囊实性神经鞘瘤较为特征性的表现。实性病灶呈＂同心圆样＂强化可能是实性神经鞘瘤比较有价值的征象。MRI上肿瘤实质部分呈稍长T1稍长T2信号,囊性部分呈长T1长T2信号,病灶周围可见水肿信号;＂靶征＂是特征性的MRI表现。结论 不典型神经鞘瘤可发生在身体任何部位,熟悉其影像学特点对诊断很有帮助。     

The value of magnetic resonance imaging in the diagnosis of orbital floor fractures

The value of MRI in the diagnosis of acute orbital floor fractures has not been clearly defined. We therefore compared MR findings with CT findings in patients with orbital trauma. In 30 patients with isolated orbital trauma both coronal CT and coronal MRI were used to examine the orbits and the adjacent paranasal sinuses. Visualization of anatomical landmarks, the kind and extent of traumatic lesions, as well as artifacts were scored. The scores were compared using the Wilcoxon matched-pairs signed-rank test. Interexamination agreement between the two methods was calculated using a kappa analysis. All examinations had diagnostic quality: 30 fractures of the orbital floor (9 right and 21 left orbital floor fractures) were identified. In addition, CT showed fractures of the medial orbital wall in 19 patients (63.3%), of the lateral wall in 10 patients (33.3%), of the zygomatic arch in 2 patients (6.7%), and of the maxillary sinus in 4 patients (13.3%). Soft tissue herniation was shown in 13 patients (inferior rectus muscle twice, orbital fat in 11 cases). Magnetic resonance imaging demonstrated soft tissue herniation in 21 patients: muscle in 4, orbital fat in 17 cases. Magnetic resonance imaging is able to demonstrate orbital floor fractures as sensitively as CT, but CT is superior to MRI in showing small and associated fractures; therefore, CT remains in orbital fractures the imaging modality of choice. Magnetic resonance imaging is superior to CT in showing soft tissue herniations; therefore, MRI may have a role as an adjunct to CT if soft tissue entrapment remains unclear.     

CT Features of an unusual calcified schwannoma of the superior laryngeal nerve

We report the CT findings in a patient with a lateral neck mass histologically diagnosed as a laryngeal schwannoma but presenting some uncommon CT features. CT showed unusual calcified components, very rarely observed and potentially misleading for diagnosis. However, this imaging feature can be found in ancient schwannomas. Our case is, therefore, a very rare one and reviews the main differential diagnoses.     

Schwannoma of the extremities: the role of PET in preoperative planning.

The aim of this study was to determine the relative utility of various preoperative diagnostic imaging modalities for the evaluation of benign schwannoma, including positron emission tomography (PET) utilising fluorine-18 fluoro-2-deoxy-D-glucose (FDG) and fluorine- 18 alpha-methyl tyrosine (FMT). computed tomography (CT), magnetic resonance imaging (MRI) and digital subtraction angiography (DSA). We retrospectively reviewed imaging findings in 22 patients with 25 histopathologically documented benign schwannomas of the extremities. Pre-operative imaging included: FDG-PET (n=22), FMT-PET (n=17), MRI (n=25), CT (n=16) and DSA (n=17). All 22 lesions examined by PET with FDG and/or FMT showed accumulation. The standardised uptake values (SUVs) for FDG-PET for the 22 examined tumours ranged from 0.33 to 3.7, and eight of them (36.4%) were assessed as malignant on the basis of their uptake. The SUVs for FMT ranged from 0.44 to 1.47, and 15 out of the 17 evaluated (88.2%) showed values indicating the tumour to be benign. CT demonstrated variable attenuation and contrast enhancement. MRI signal characteristics were relatively consistent: iso-signal or darker than skeletal muscle on T1-weighted and isosignal or brighter than subcutaneous fat on T2-weighted images. The venous tumour staining depicted on DSA was found to be significantly correlated with FDG accumulation. All tumours but one were treated by surgical enucleation. One tumour suspected to be malignant on the basis of imaging findings was treated with primary wide resection. Although CT, MRI and PET studies are all useful for the detection and localisation of schwannoma, our findings suggest that, among the imaging modalities studied, FMT-PET may be the most reliable technique for the differentiation of benign schwannoma from malignancy.     

Schwannoma of the tip of the nose: MRI

We report a schwannoma with a rare location at the tip of the nose in a 20-year-old woman with an otherwise unremarkable medical history. The imaging findings unterline the usefulness of MRI in narrowing down the differential diagnosis of masses in this region. Once the diagnosis was focussed on a neural origin of the mass, the exact nature of the tumour could not be predicted from the MRI, although the presence of a capsule on imaging studies as well as at operation suggested it was probably a schwannoma. A schwannoma must be considered when one encounters a sharply delineated mass at the tip of the nose, showing high signal on T2-weighted images and strongly contrast enhancement. Received: 17 July 1997 Accepted: 2 October 1997     

CT and MR imaging of intralabyrinthine schwannoma: report of two cases and review of the literature

Two cases of intralabyrinthine schwannoma were studied with computed tomography (CT) and magnetic resonance (MR) imaging. On CT scans, a soft-tissue mass was identified in the round window niche in both cases. Widening of the basilar turn of the cochlea and characteristic erosion of the promontory were noticed in one case. Preoperative MR imaging (performed in only one case) revealed a soft-tissue mass in the labyrnth, extending into the round window niche. Findings at CT and MR imaging are discussed, and a differential diagnosis is given. The literature is reviewed. The authors' findings suggest that CT and MR imaging may prove very valuable in the previously difficult preoperative diagnosis of these tumors. In the setting of progressive sensorineural hearing loss, atypical Meniere disease, or recurrent vertigo, the presence of a mass in the labyrinth or labyrinthine windows- delineated on CT or MR images, despite a normal internal auditory canal, cerebellopontine angle, or brain stem - is highly suggestive of intralabyrinthine schwannoma.     

CT和MRI对口腔和口咽部病变的诊断价值

目的：探讨CT和MRI对口腔及口咽部病变的诊断价值。方法：回顾性分析63例经病理及细胞学证实的口腔口咽部病变的CT、MRI资料,其中恶性肿瘤40例,良性肿瘤18例,感染性病变5例。结果：40例恶性肿瘤中,CT检查24例,MRI检查16例,除各有一例浅表型溃疡未能显示外,其余病灶及范围均较清晰显示,两者的区别在于MRI显示肿瘤侵犯邻近结构及深部组织方面优于CT;两者在显示良性病变的大小方面与手术结果相同。结论：CT及MRI对口腔口咽部病变的诊断有重要价值,MRI稍优于CT。     

Correlative CT, MRI and histological findings of hepatic Echinococcus alveolaris: a case report.

Diagnosis of liver infestation by Echinococcus alveolaris (EA) is based on serologic, sonographic and CT findings. Literature review yielded only one report discussing the MRI findings of hepatic EA infestation. In this report, we present a case of hepatic EA infestation with its correlative CT, MRI and histological findings. CT showed hypodense mass involving more than half of the liver with rim and central calcifications. MRI revealed hypointense signal of the infiltrative mass on both T1- and T2-weighted images. On MRI, the portal vein branches were seen coursing through the lesion. Neither CT nor MRI demonstrated any contrast enhancement of the mass. On the histological examination, abundant fibrous and hyalinized tissue surrounding multiple small cysts were observed. MRI may provide invaluable information in the diagnosis of EA infestation of the liver, either by disclosing the infiltrative pattern of infestation without significant effect to vascular structures, or by the signal characteristics.