CT and MRI of the middle ear

Summary High-resolution computed tomography (HRCT) provides excellent contrast between osseous structures, air and soft tissue in conjunction with high spatial resolution. Therefore, thin-section HRCT with bone window setting is the method of choice for the examination of the middle ear structures. The indications are acute and chronic inflammatory changes, cholesteatoma and tumor, the “postoperative middle ear”, and malformations. In most cases, HRCT enables differentiation between inflammatory changes, cholesteatoma, and tumor. The excellent depiction of subtle osseous details enables the identification of erosions of the ossicles or of the bony walls of the mastoid cells, of osseous defects of the tegmen, of the bony labyrinth, and of the tympanic course of the facial canal. In addition, HRCT enables excellent depiction of reconstructions of the ossicles or prosthesis of the ossicles. Although HRCT is the first method of choice, magnetic resonance imaging (MRI) may provide additional information and lead to a more accurate diagnosis in some cases. This is explained by the excellent soft tissue contrast provided by MRI. In addition, MRI offers the possibility of using various pulse sequences and the administration of IV contrast material. Therefore, MRI may allow the differentiation between inflammatory changes, cholesteatoma, and tumor in those cases in which accurate diagnosis cannot be made by HRCT. The differentiation between a meningocele or meningoencephalocele and other entities such as tumors or cholesteatoma can be established by MRI. Furthermore, MRI can accurately depict cases of labyrinthitis or of neuritis of the facial nerve or of intracranial disease caused by middle ear processes, while this is not always possible by HRCT. In summary, HRCT of the middle ear is the method of choice, but MRI may provide supplementary information in those cases in which accurate diagnosis cannot be established by HRCT.      

Computed tomography and magnetic resonance imaging of acquired abnormalities of the inner ear and cerebello-pontine angle

CT and MRI of acquired abnormalities of the inner ear and cerebello-pontine angle present themselves with very typical findings. The imaging should be adapted to the pathology looked for and either CT or MRI should be used alone or in combination. CT, especially high resolution CT (HRCT), provides an excellent bone contrast, while MRI has a much superior soft tissue contrast. Acute inflammatory changes of the inner ear are solely depicted by contrast-enhanced MRI. HRCT excellently depicts osseous changes of the inner ear and cerebellopontine angle such as chronic ossifying labyrinthitis occurring after acute labyrinthitis, otosclerotic or traumatic changes. Tumorous changes not yielding to bony changes are best delineated by MRI. Posttraumatic hemorrhage and chronic fibrotic changes within the labyrinth are depicted by MRI, only. In conclusion HRCT and MRI are excellent methods to delineate acquired abnormalities of the inner ear and cerebello-pontine angle. HRCT best depicts osseous changes while MRI best depicts soft tissue changes. HRCT and MRI are not concurrent methods but should better be used as complementary methods for imaging acquired abnormalities of inner ear and cerebellopontine angle.     

内耳化脓坏死性迷路炎的影像学表现

目的：探讨内耳化脓坏死性迷路炎影像学诊断价值。方法：回顾性分析6例经手术病理和临床诊断的化脓坏死性迷路炎的CT和MRI表现,总结分析其影像学特点。结果：6例行颞骨高分辨力CT扫描（HRCT）,轴面和冠状面CT均显示有不同程度内耳骨迷路的破坏,并伴软组织增生,其中4例有高密度死骨形成;MRI检查6例,显示膜迷路部分或全部为软组织病变充填,增强后不均质明显强化,死骨在T1WI、T2WI均显示为小片低信号或无信号,增强后无强化。结论：HRCT可显示骨迷路结构的破坏范围及死骨的存在,有诊断价值;MRI显示颅内并发症明显优于CT,两者结合可诊断内耳化脓坏死性迷路炎。     

慢性中耳炎的HRCT诊断

目的探讨慢性中耳炎的HRCT特征、诊断及鉴别诊断.方法回顾性分析105例慢性中耳炎患者术前临床和HRCT检查资料,并与手术病理结果对照.结果36例胆脂瘤型中耳炎HRCT表现为鼓室或/及鼓窦内团块状软组织影和骨质改变,包括听骨硬化、移位、破坏,盾板破坏及中耳腔扩大,有的还伴有乙状窦、天盖、水平半规管的破坏.69例渗出肉芽型中耳炎HRCT表现多呈斑片状、条索状或网状软组织影,部分可见液平,听骨移位及破坏较轻.结论依据中耳腔内软组织影的分布、形态及骨质改变等特点,大多数慢性中耳炎可籍HRCT做出诊断或鉴别诊断.     

中耳炎侵犯迷路的影像表现

目的:探讨中耳炎侵犯迷路的HRCT和MRI表现及其诊断价值与局限。方法:回顾性分析24例(24耳),经临床综合诊断为中耳炎侵犯迷路患者的HRCT和MRI表现。结果:骨迷路破坏8耳,HRCT诊断7耳,表现为骨迷路破坏,中耳内病变与迷路腔相通。迷路腔淋巴液受侵14耳,HRCT显示骨迷路破坏9耳,骨迷路完好5耳。MRI示8耳迷路腔淋巴液于T1WI上信号升高,T2WI信号无变化,其中7耳增强扫描有明显强化,1耳轻度强化;5耳迷路腔淋巴液于T1WI信号升高,T2WI信号减低,其中4耳明显强化,1耳轻度强化;1耳迷路腔淋巴液于T1WI和T2WI信号无变化,增强后明显强化。迷路增生、硬化1耳,HRCT显示耳蜗骨迷路骨质增厚、硬化,迷路腔变窄;MRI上表现为蜗腔变细。骨迷路广泛破坏1耳,位于耳蜗后部骨迷路内,HRCT显示骨迷路内大片软组织密度影,周围骨质破坏,内部可见形态不规则死骨;MRIT1WI和T2WI显示骨迷路内均呈混杂信号,增强后有不均匀强化。结论:HRCT和MRI可显示中耳炎侵犯迷路的程度,能为临床制定治疗方案提供重要信息。     

External auditory canal cholesteatoma: clinical and imaging spectrum

BACKGROUND AND PURPOSE: Cholesteatoma is an inflammatory lesion of the temporal bone that uncommonly involves the external auditory canal (EAC). In this large case series, we aimed to define its imaging features and to determine the characteristics most important to its clinical management. METHODS: Thirteen cases of EAC cholesteatoma (EACC) were retrospectively reviewed. Clinical data were reviewed for the history, presentation, and physical examination findings. High-resolution temporal bone CT scans were examined for a soft-tissue mass in the EAC, erosion of adjacent bone, and bone fragments in the mass. The middle ear cavity, mastoid, facial nerve canal, and tegmen tympani were evaluated for involvement. RESULTS: Patients presented with otorrhea, otalgia, or hearing loss. Eight cases were spontaneous, and five were postsurgical or post-traumatic. CT imaging in all 13 cases showed a soft-tissue mass with adjacent bone erosion. Intramural bone fragments were identified in seven cases. This mass most often arose inferiorly (n = 8) or posteriorly (n = 8), but it was circumferential in two cases. We noted middle ear extension (n = 5), mastoid involvement (n = 4), facial canal erosion (n = 2), and tegmen tympani dehiscence (n = 1). CONCLUSION: Temporal bone CT shows EACC as a soft-tissue mass within the EAC, with adjacent bone erosion. Bone fragments may be present within the mass. The cholesteatoma may extend into the mastoid or middle ear, or it may involve the facial nerve canal or tegmen tympani. Recognition of this entity and its possible extension is important because it may influence clinical management.     

骨化性迷路炎的CT和MRI表现

目的 探讨骨化性迷路炎的HRCT和MRI表现。资料与方法 对9例14耳骨化性迷路炎进行回顾性分析，9例均行HRCT扫描，其中6例行MRI检查。结果 14耳HRCT表现为迷路内部分或全部结构密度增高，其中13耳累及耳蜗，6耳累及半规管，9耳蜗宙区受累，4耳前庭宙受累，2耳前庭骨化，2耳耳蜗水管区骨质明显硬化。6例8耳MRI各序列表现为4耳耳蜗膜迷路变形，4耳内耳膜迷路全部末显示；2例2耳行增强扫描病变无强化。结论HRCT和MRI相结合能够对骨化性迷路炎做出正确诊断。     

中耳胆脂瘤的HRCT诊断

目的 :探讨中耳胆脂瘤HRCT特征、诊断及鉴别诊断。材料和方法 :回顾性分析 66例中耳胆脂瘤患者术前临床和HRCT检查资料 ,并与手术病理结果对照。结果 :66例中耳胆脂瘤HRCT表现为鼓室 /鼓窦内团块状软组织影和骨质改变 ,包括听骨硬化、移位、破坏 ,盾板破坏及中耳腔扩大 ,有的还伴有乙状窦、天盖、面神经管及水平半规管的破坏。结论 :依据中耳腔内软组织影的分布、形态及骨质改变等特点 ,中耳胆脂瘤可通过HRCT做出诊断和鉴别诊断。     

颞骨迷路炎的影像学诊断及其相关病因学分析

目的:探讨骨化性迷路炎的影像学表现,并对相关的病因学进行分析,以提高对本病的认识。方法:搜集临床患有中耳炎、胆脂瘤、脑膜炎和外伤等41例患者(55耳),经过临床和CT、MRI检查确诊为骨化性迷路炎,回顾性分析其CT和MRI影像表现。结果:HRCT示耳蜗基底周内可见点状高密度影、"弧形"高密度影或耳蜗普遍密度增高,呈"磨玻璃"样高密度影,伴有管腔不规则狭窄者24耳,其中蜗轴增粗、骨性螺旋板增宽各2耳;耳蜗完全骨性闭塞4耳。前庭受累表现为狭窄、密度增高。各半规管受累表现为密度增高、管腔狭窄或完全骨性闭塞。前庭窗、蜗窗受累者表现为其内密度增高、狭窄。受累机率由高至低依次是水平半规管、后半规管、耳蜗、上半规管、前庭窗、蜗窗及前庭。22耳MRI表现异常,T1WI为等信号或高信号,T2WI为信号减低或消失,增强后早期可见强化。受累机率由高至底依次是耳蜗、水平半规管、上半规管、后半规管及前庭,表现为轮廓不规则或狭窄。结论:CT、MRI对诊断骨化性迷路炎及其判断病变累及部位具有重要意义。     

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.     

蜗神经发育异常影像学诊断

目的:探讨蜗神经发育异常的影像学表现。方法:回顾性分析17例影像诊断为蜗神经发育异常患者的CT及MRI表现,总结相关征象。17例患者均行MRI检查,常规行横轴面和冠状面SE T_1 WI,FSE T_2 WI,并采用三维快速平衡稳态(3D FIESTA)序列进行内耳成像;CT检查采用横轴面HRCT扫描。结果:MRI检查显示17例33耳蜗神经发育异常中,25耳蜗神经未显示,8耳显示细小。蜗神经未显示的25耳中,进行了HRCT检查的19耳均显示蜗神经孔异常改变.其中伴有内耳道狭窄18耳,骨迷路畸形15耳,前庭神经异常10耳,面神经细小2耳。蜗神经显示细小的8耳中,4耳伴有蜗神经孔异常改变,4耳内耳道呈壶腹状或喇叭状,5耳伴有内耳Mondini畸形。结论:HRCT显示蜗神经孔区异常改变可初步提示蜗神经发育异常。HRCT及MRI联合使用可较准确的显示蜗神经发育异常,对于临床人工耳蜗术前评价具有重要的指导意义。     

颞骨CT影像检查技术

本文综述了颞骨的现代影像学检查技术，HRCT是颞骨首选的影像学检查方法，对于颞骨解剖及病变的显示有很大优势。螺旋CT有多种后处理技术可应用于颞骨检查：MPR能对颞骨进行多方位观察，CPR对面神经等结构全貌显示，SSD、CTVE能够立体全方位显示解剖及病变并可进行模拟手术，VR显示内耳膜迷路及神经。MRI能够在一定程度上区分病变的病理性质，水成像技术清晰显示膜迷路。     

Imaging appearances of unusual conditions of the middle and inner ear

Requests for imaging of patients complaining of deafness and other symptoms related to the petrous bone are becoming increasingly common. Although much of this work is related to the exclusion of vestibular schwannomas by MRI, high-resolution CT is available in most departments and is necessary for the evaluation of many conditions of the middle ear and bony labyrinth. In this pictorial review, some of the more unusual conditions that may be encountered in the middle and inner ear are presented, which might not be overly familiar to non-otological radiologists, illustrating the roles of CT and MRI.     

Computed tomography and magnetic resonance imaging of congenital abnormalities of the temporal bone

Congenital abnormalities of the temporal bone are mostly accompanied by conductive or sensori-neural hearing loss. Before any therapeutic procedures are done high resolution CT (HRCT) and magnetic resonance imaging (MRI) should be performed to establish the correct diagnosis and to plan the potentially surgical intervention. HRCT best depicts osseous changes especially those of the external auditory canal and the middle ear containing the ossicles and the osseous structures of the temporal bone and the petrous bone containing the inner ear. MRI excellently shows soft tissue changes of the inner ear especially on the high resolution 3DT2-weighted sequences which give a superb contrast between the nerves and the cerebro-spinal fluid. Malformations of the external auditory canal consists of aplasia or hypoplasia and those of the middle ear range form extreme hypoplasia or aplasia to very mild deformations of the ossicles. Malformations of the inner ear also range form complete aplasia to very mild hypoplasia of the organs of the inner ear as well as malformations concerning the nerves in the internal auditory canal range from aplasia to hypoplasia. Malformations of the temporal bone can either occur isolated or in combination in which malformations of the external and middle ear may be accompanied by those of the inner ear. Furthermore, malformations of the temporal bone may also occur in otofacial, otocervical or otoskeletal syndromes. These syndromes may be accompanied by certain malformations of the temporal bone. HRCT and MRI are both excellent methods to depict congenital abnormalities of the temporal bone and of the inner ear and should be used as complementary methods because HRCT best depicts osseous changes and MRI superbly depicts soft tissue changes. Both methods are important to establish the correct diagnosis to plan the therapeutic procedures.     

颞骨内面神经病变的影像学表现

目的总结分析面神经病变的影像学检查方法和表现,提高诊断准确性。资料与方法回顾性分析31例经手术病理或临床跟踪随访证实的面神经病变的CT和MRI表现,31例行MR扫描,其中28例行平扫和增强扫描,3例仅行平扫;19例行CT扫描。结果（1）面神经损伤13例,8例行CT扫描,6例显示面神经管骨折,2例表现正常;13例MRI扫描均表现为面神经增粗,其中10例增强扫描显示面神经明显强化。（2）面神经炎14例,7例行CT扫描,1例因岩尖胆脂瘤致面神经管迷路段、前膝部、鼓室段前部骨质破坏,6例面神经管未见异常;14例MRI增强扫描显示面神经节段性异常强化。（3）面神经鞘瘤4例,CT表现为受累面神经管骨质破坏和软组织肿块;MRI表现为面神经节段性增粗,呈长T1、长T2信号,信号不均匀,增强后不均匀强化。经统计学处理,MRI显示颞骨内面神经病变明显优于CT（P＜0．01）。结论HRCT可显示面神经管的异常,MRI尤其是MR增强扫描可显示面神经病变的形态、部位、范围及强化表现,有助于病变的诊断和鉴别诊断。     

Imaging and clinical characteristics of temporal bone meningioma

BACKGROUND AND PURPOSE: Imaging characteristics of temporal bone meningioma have not been previously reported in the literature. CT and MR imaging findings in 13 cases of temporal bone meningioma are reviewed to define specific imaging features. METHODS: A retrospective review of our institutional case archive revealed 13 cases of histologically confirmed temporal bone meningioma. CT and MR imaging studies were reviewed to characterize mass location, vector of spread, bone changes, enhancement characteristics, and intracranial patterns of involvement. Clinical presenting signs and symptoms were correlated with imaging findings. RESULTS: Thirteen temporal bone meningiomas were reviewed in 8 women and 5 men, aged 18-65 years. Meningiomas were stratified into 3 groups on the basis of location and tumor vector of spread. There were 6 tegmen tympani, 5 jugular foramen (JF), and 2 internal auditory canal (IAC) meningiomas. Tegmen tympani and JF meningiomas were characterized by spread to the middle ear cavity. IAC meningiomas, by contrast, spread to the cochlea and vestibule. Hearing loss was the most common clinical presenting feature in all cases of temporal bone meningioma (10/13). The presence of tumor adjacent to the ossicles strongly correlated with conductive hearing loss (7/9). CONCLUSION: Meningioma involving the temporal bone is rare. Three subgroups of meningioma exist in this location: tegmen tympani, JF, and IAC meningioma. Tegmen tympani and JF meningiomas spread to the middle ear cavity. IAC meningiomas spread to intralabyrinthine structures. Conductive hearing loss is commonly seen in these patients and can be surgically correctable.     

迷路炎的MRI诊断

目的探讨MRI在迷路炎诊断中的作用。方法观察10例临床提示为迷路炎同时存在MRI异常表现患者的MRI图像,总结其变化特征。结果10例10耳中,T2WI上均可见内耳1个或多个结构信号发生异常改变,其中,6耳病变区信号不同程度减低,4耳病变区信号消失。T1WI上7耳可见内耳1个或多个结构信号出现异常,其中,4耳病变区信号略增高,3耳病变区信号消失。FIESTA图像与T2WI图像显示结果相同。行增强扫描的7例7耳中,4耳病变区可见不同程度强化。10耳中,耳蜗受累9耳;前庭受累7耳;半规管受累6耳。结论MRI可以显示内耳膜迷路信号的异常改变,在诊断较早期迷路炎时具有重要价值。     

外中耳先天畸形的HRCT研究

目的 研究外中耳先天畸形的高分辨CT（HRCT）表现,为临床诊断和治疗提供准确信息。资料与方法 对临床诊断的外、中耳先天畸形35例行HRCT扫描,单纯横断位扫描5例,横断位加冠状位扫描30例。结果 （1）外耳畸形32例共42耳,其中外耳道骨性闭锁30耳,显示闭锁板为完全性26耳,不完全性4耳。膜性闭锁5耳。双侧分别为不同类型闭锁1例。外耳道狭窄7耳,其中狭窄合并对侧闭锁1例。合并畸形中,面神经管垂直段明显前移22耳,下颌髁状突明显后上移25耳,乙状窦前移4耳,均见于骨性外耳道闭锁。伴发的中耳畸形主要为小鼓室及不同程度的听骨发育不全或缺如。合并内耳发育不全1例。（2）单纯性中耳畸形3例共6耳,均表现为听小骨异常。合并小鼓室1例,耳咽管和鼓室窦畸形扩大1例。结论 HRCT能准确显示外中耳先天畸形的类型、程度以及合并畸形,为临床治疗方案的正确制定提供重要的参考依据。     

Virtual endoscopy of the middle ear

Virtual endoscopy is a computer-generated simulation of fiberoptic endoscopy, and its application to the study of the middle ear has been recently proposed. The need to represent the middle ear anatomy by means of virtual endoscopy arose from the increased interest of otolarygologists in transtympanic endoscopy. In fact, this imaging method allows the visualization of middle ear anatomy with high detail, but it is evasive and is essentially used for surgical guidance. Virtual endoscopy provides similar perspectives of the tympanic cavity but does not require the tympanic perforation. In the study of the middle ear, specific attention is given to the retroperitoneum. This region contains elevations of the medial wall (pyramidal eminence and ridge, styloid eminence and ridge, subiculum, ponticulus) and depressions (sinus tympani, posterior sinus tympani, facial sinus, fossula of Grivot, oval window fossula), which can be effectively displayed by virtual endoscopy. Virtual endoscopy is foreseen as a useful tool in preoperative management of patients who are candidates for middle ear surgery, since it can predict with high detail the patient's specific anatomy by imaging perspectives familiar to otosurgeons. Received: 3 May 2000 Accepted: 8 June 2000     

Diagnostik des Felsenbeins

Diseases of the temporal bone should be diagnosed by high resolution computed tomography (CT) and magnetic resonance imaging (MRI). Because of the excellent imaging of bony structures, CT is the method of choice for diagnosing pathologies of the external auditory channel, middle ear, and mastoid. Imaging of trauma is performed with CT. For examining the labyrinth system and interior auditory channel, MRI is the method of choice. This article gives an overview of the anatomy of the temporal bone and describes the most important pathologies.