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.     

CT and MRI characteristics of tumours of the temporal bone and the cerebello-pontine angle

Tumours lesions of the temporal bone and of the cerebello-pontine angle are rare. This tumours can be separated into benign and malignant lesions. In this paper the CT and MRI characteristics of tumours of the temporal bone and the cerebello-pontane angle will be demonstrated. High resolution CT (HRCT) as usually performed in the axial plane are using a high resolution bone window level setting, coronal planes are the reconstructed from the axial data set or will be obtained directly. With the MRI FLAIR sequence in the axial plane the whole brain will be scanned either to depict or exclude a tumour invasion into the brain. After this,T2-weighted fast spin echo sequences or fat suppressed inversion recovery sequences in high resolution technique in the axial plane will be obtained from the temporal bone and axial T1-weighted spin echo sequences before and after the intravenous application of contrast material will be obtained of this region. Finally T1-weighted spin echo sequences in high resolution technique with fat suppression after the intravenous application of contrast material will be performed in the coronal plane. HRCT and MRI are both used to depict the most exact tumorous borders. HRCT excellently depicts the osseous changes for example exostosis of the external auditory canal, while also with HRCT osseous changes maybe characterized into more benign or malignant types. MRI has a very high soft tissue contrast and may therefore either characterize vascular space-occupying lesions for example glomus jugulare tumours or may differentiate between more benign or malignant lesions. In conclusion HRCT and MRI of the temporal bone are excellent methods to depict and mostly characterize tumour lesions and can help to differentiate between benign and malignant lesion. These imaging methods shall be used complementary and may have a great impact for the therapeutic planning.     

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.     

Benigne und maligne Veränderungen der Innenohr- und Kleinhirnbrückenwinkelregion

Tumorous lesions in the region of the inner ear and cerebellopontine angle are very rare and can be classified into benign and malignant disease forms. This contribution presents and explains the CT and MRI characteristics of these tumors.High-resolution computed tomography (HRCT) in the axial projection is applied for evaluation in the high-resolution bone window. The coronary slices can be reconstructed from the axial datasets or in individual cases examined in the coronary plane.HRCT excellently demonstrates osseous lesions and in individual cases - e.g., exostoses - it can simply suffice to perform HRCT of the temporal bone, while HRCT is also excellent for detecting osseous lesions to determine whether the tumor is benign or malignant.MRI, on the other hand, excellently shows the extent of tumor spread because of its superb soft tissue contrast. Consequently, HRCT and MRI images of the inner ear and cerebellopontine angle provide meaningful information for visualization and classification of tumorous lesions. The two methods should not be considered as competing but rather as complementary and among other aspects exert considerable influence on the therapeutic approach.     

儿童蜗神经发育不良的影像学表现

目的：探讨儿童蜗神经发育不良（CND）的MRI及高分辨力CT表现。方法：回顾性分析34例（60耳）蜗神经发育不良的颞骨HRCT及内耳和内耳道MRI表现。分析比较3种影像学表现诊断CND的能力。结果：MRI显示蜗神经发育不良60耳,伴前庭神经异常28耳,伴面神经细小3耳,伴内耳畸形28耳。HRCT显示内耳道狭窄32耳,蜗神经孔狭窄28耳,骨性封闭25耳。MRI诊断CND明显优于CT（P〈0.001）;以HRCT显示蜗神经孔狭窄或封闭作为诊断CND的依据明显优于以HRCT显示IAC狭窄作为诊断CND的依据（P=0.043）。结论：MRI能准确显示CND,HRCT显示蜗神经孔狭窄或封闭高度提示CND,内耳道正常不能排除CND。     

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。     

Cross-sectional imaging of primary osseous hemangiopericytoma

The aim of this study was to assess cross-sectional imaging features and the value of CT and MRI in primary hemangiopericytoma of bone. In five patients with histologically proven primary osseous hemangiopericytoma CT and MR scans were evaluated retrospectively. Both CT and MRI were available in four patients each. In three patients both imaging techniques were available. On CT primary hemangiopericytoma of bone presents as an expansive lytic lesion with bone destruction and inhomogeneous contrast enhancement. Magnetic resonance imaging depicts osseous hemangiopericytoma as hyperintense lesion on T2-weighted images with intermediate signal intensity on T1-weighted images. Curvilinear tubular structures of signal void in the tumor matrix on T1-weighted images and corresponding hyperintense structures on T2-weighted and on fat-suppressed short tau inversion recovery images were present in three patients. Although cross-sectional imaging findings are non-specific, they add to the diagnosis and provide valuable information about the extent of bone destruction and local tumor spread in patients with primary osseous hemangiopericytoma. While CT demonstrates the extent of bone destruction best, MRI better visualizes medullary and soft tissue extension of the tumor. Curvilinear signal abnormalities support the diagnosis of hemangiopericytoma of bone. This imaging pattern is best visualized on fat-suppressed or contrast enhanced T1-weighted MR images.     

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.      

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas will be described in this paper. The pre- and postoperative imaging of the temporal bone was performed with HRCT and MRI.HRCT and MRI were performed in the axial and coronal plane. MRI was done with T2 weighted and T1 weighted sequences both before and after the intravenous application of contrast material. All imaging findings were confirmed clinically or surgically. The preoperative cholesteatoma-caused complications depicted by HRCT included bony erosions of the ossicles, scutum, facial canal in the middle ear, tympanic walls including the tegmen tympani, and of the labyrinth. The preoperative cholesteatoma-caused complications depicted by MRI included signs indicative for labyrinthitis, and brain abscess. Postoperative HRCT depicted bony erosions caused by recurrent cholesteatoma,bony defects of the facial nerve and of the labyrinth, and a defect of the tegmen tympani with a soft tissue mass in the middle ear. Postoperative MRI delineated neuritis of the facial nerve, labyrinthitis, and a meningo-encephalocele protruding into the middle ear. HRCT and MRI are excellent imaging tools to depict either bony or soft tissue complications or both if caused by acquired cholesteatomas. According to our findings and to the literature HRCT and MRI are complementary imaging methods to depict pre- or postoperative complications of acquired cholesteatomas if these are suspected by clinical examination.     

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。     

Congenital Aural Atresia: What the Radiologist Needs to Know?

Congenital aural atresia (CAA) is characterized by hypoplasia or aplasia of external auditory canal associated with auricular deformity. It also embodies a spectrum of temporal bone abnormalities including anomalies of middle ear, ossicles, facial nerve, oval window, round window, mastoid pneumatization, temporomandibular joint and occasionally inner ear and vascular anomalies. The management in such patients is variable and consists of rehabilitative hearing aids or surgical correction depending on various patient factors like associated temporal bone abnormalities, degree of hearing impairment and laterality. Surgical management if planned, depends on the extent of associated temporal bone anomalies and hence necessitates comprehensive knowledge about the normal and abnormal anatomy of these structures. High resolution computed tomography (HRCT) is the optimal investigation which provides required anatomical information and plays a pivotal role in deciding the management strategy. This pictorial review aims to review the spectrum of anomalies involving critical structures in CAA on HRCT along with their clinical significance.     

Fast spin-echo high-resolution MR imaging of the inner ear.

Advances in MR imaging continue to improve our ability to evaluate temporal bone anatomy and disease. CT remains the procedure of choice for fine-detail imaging of bone structures such as ossicular anatomy, but it is not the ideal imaging technique for soft-tissue structures (e.g., the membranous labyrinth and neural structures). Conventional spin-echo MR techniques used to image these structures cannot yield excellent contrast and spatial resolution in clinically acceptable time frames. Conventional spin-echo T1-weighted images lack tissue contrast between fluid (e.g., CSF, endolymph, perilymph), neural tissue, otic capsule septa, and surrounding temporal bone. Conventional T2-weighted imaging of the inner ear is needed to reveal the natural contrast between fluid, neural structures, and bone; unfortunately, the use of conventional T2-weighted images is limited by time constraints when large-matrix, thin-section techniques with more than one excitation are used. Fast spin-echo imaging is a recently developed technique that can provide T2-weighted, thin-section (2-mm) high-resolution images with excellent contrast in a fraction of the time needed for conventional spin-echo techniques. This speed advantage allows us to obtain high-resolution images in clinically acceptable time frames. Images produced by this technique are a useful addition, in conjunction with routine T1- and T2-weighted spin-echo images, in the diagnosis of disorders of the inner ear.     

正常颞骨斜矢状面CT扫描的解剖学表现

目的 探讨听骨,内耳骨迷路及面神经骨管等结构在CT斜矢状面的影像学表现,方法 利用自制木架固定器对63只正常耳行直接斜矢状面扫描,所得影像与尸体颞骨解剖相对照。结果 显示外耳道,上鼓室,乳突窦,听小骨,面神经管乳突段及内耳骨迷路63只耳（100％）,面神经管鼓室段42只耳（66．7％）,面神经管膝部55只耳（87．3％）,前庭导水管58只耳（92．1％）,结论 直接斜矢状面扫描是继横,冠状面扫描之后的一个重要扫描方法 对耳疾病的诊断和临床手术有重要意义。     

侵及颈静脉孔区的原发性中耳癌的CT、MRI诊断

目的 探讨侵及颈静脉孔区的原发性中耳癌的CT、MRI特点.方法 回顾性分析7例经手术病理证实的侵及颈静脉孔区原发性中耳癌患者的CT、MRI资料,其中6例行高分辨率CT(HRCT)扫描,1例行常规CT增强扫描,7例均行MR平扫+增强.结果 HRCT显示鼓室、鼓窦、外耳道深部及颈静脉孔区软组织病灶伴不规则虫蚀样骨质破坏,涉及颈静脉孔(7例)、咽鼓管骨性段(7例)、面神经管(4例)、颈动脉管(4例)、外耳道前后壁(3例)、听小骨(2例)及前庭窗、水平半规管(1例)等结构的破坏.4例病变密度较均匀,CT值约30～55 HU,2例肿块内见少许小片状高密度影.1例CT增强显示中度较均匀强化.MR平扫示边界不清软组织肿块,与脑灰质相比,T1WI呈等、略低信号,T2WI呈等、略高信号,其中5例信号较均匀,2例肿块内见少许小片状T1WI、T2WI低信号灶,增强扫描5例呈中度较均匀强化,2例不均匀强化,内见小片状无强化区.MRI显示4例侵及颈内动脉,1例侵及乙状窦.结论 原发性中耳癌可广泛侵及颈静脉孔区,易造成误诊.HRCT可准确显示中耳癌骨质破坏特点及范围,咽鼓管骨性段破坏可帮助减少误诊;MRI能更清楚显示病变范围,肿瘤信号及强化方式有一定特点.     

Three-dimensional reconstructed MR imaging of the inner ear

The three-dimensional Fourier transform fast imaging with steady precession (FISP) technique was used to obtain high-resolution magnetic resonance (MR) images of the temporal bone region and to generate three-dimensional reconstructed images of the inner ear. The three-dimensional reconstructed images of the inner ear were directly synthesized from two-dimensional images of the temporal bone region by means of an external processing computer. With use of three-dimensional reconstructed images and stereoscopic observations, structures inside the temporal bone region and the positional relationship among them were easily recognized. These structures are difficult to demonstrate with two-dimensional images. This three-dimensional method was also shown to be useful for recognition of disease and anatomic malformations in the temporal bone region.     

低场磁共振CISS序列内耳水成像相关参数的控制

目的:探讨低场磁共振CISS序列内耳水成像相关参数的选择,以提高其临床应用水平。方法:对10例正常成人的10对内耳分别使用常规CISS序列、参数调整后的CISS序列进行配对扫描,之后对图片质量进行评分形成配对数据资料。结果:参数调整后的CISS序列的内耳水成像图像质量明显优于常规CISS序列。结论:在低场磁共振上对CISS序列相关参数的选择优化后,能明显提高内耳水成像图像质量,从而提高其临床应用水平,适合基层医院使用。     

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.     

高分辨率CT显示听小骨能力的研究

目的 探讨高分辨率CT（HRCT）单侧密集骨重建技术对听小骨细微结构的显示能力及对疾病的诊断价值。方法：收集45人，81只耳的资料，全部病例行HRCT扫描，后进行单侧局部密集骨重建，观察轴冠位的正常及异常HRCT图像对听小骨（包括砧骨豆状突，砧镫关节，镫骨前后脚、脚板）的显示情况。结果：慢性中耳乳突炎31只，外耳道先天性闭锁伴中耳发育畸形2只，颞骨骨折波及中耳1只。HRCT密集骨重建，轴冠位结合扫描，能清晰显示听小骨炎症的微小破坏，骨折等病变；结合中耳仿真内镜可清晰地显示发育畸形的听小骨。结论：HRCT能清晰，准确地显示听小骨细微结构。优于传统的CT图像，可为临床诊断和治疗提供可靠的依据。     

Temporal bone: comparison of isotropic helical CT and conventional direct axial and coronal CT.

OBJECTIVE: The objective of the study was to compare helical CT (with reformation of coronal images from the axial data set) with conventional direct axial and coronal CT of the temporal bones. SUBJECTS AND METHODS: Nineteen patients underwent both conventional 1-mm direct axial and coronal CT and helical 0.5-mm axial CT. The helical data set was reconstructed at 0.2-mm increments, and axial and coronal images were reconstructed in a plane similar to that of the conventional study, with a slice width of 0.5 mm and 0.5-mm increments. Forty small structures were evaluated independently by three observers, who were unaware of the method of imaging. Observers graded the 40 structures using a modified Likert scale. The graded differences between the two techniques were evaluated using a paired t test. Correlation between observers' gradings was evaluated using analysis of variance. RESULTS: The helical CT technique scored significantly higher than the conventional technique for many individual structures and groups of structures (scutum [p = .041], stapes footplate [p = .006], stapes crura [p = .004], oval window [p = .026], crista falciformis [p = .006], whole temporal bone [P = .012], middle ear [p = .033], inner ear [p = .021], ossicles [p = .044], and stapes [p = .010]). The correlation coefficient among observers was .91 for the whole temporal bone. CONCLUSION: Helical CT using 0.5-mm technique and reconstruction produces diagnostic images comparable with or superior to conventional 1-mm technique because helical CT can obtain thinner slices.     

Magnetic resonance tomography in the diagnosis of cerebral space occupying lesions

197 primary and secondary cerebral tumours as well as tumour-like lesions are described. T2 and T1-weighted images were obtained. Magnetic resonance imaging (MRI) offers advantages in localisation and tissue characterisation. Localisation is improved by the ability to obtain axial, coronal or sagittal images and by the absence of artifacts due to bone in lesions in the posterior fossa. A significant advantage is the excellent contrast resolution of soft tissue. On the basis of our experience, we present an overview of the most common brain tumours using MRI.