High-resolution CT of temporal bone trauma

Computed tomographic (CT) findings in 18 patients with temporal bone trauma were reviewed. Eight patients suffered longitudinal fractures of the petrous bone, which were associated with ossicular dislocation in two patients. Transverse fractures were detected in six patients, with a contralateral mastoid fracture in one patient. In four patients, the fractures were restricted to the mastoid region. Of the 14 patients in whom adequate neurologic evaluation was available, seven had a permanent facial nerve or hearing deficit while five suffered at least a transient neurologic deficit related to the temporal bone trauma. Routine head CT (10 mm sections) demonstrated only eight of 19 petrous bone injuries. Clues to such injury included opacification of the mastoid air cells (10 patients), sphenoid sinus (11 patients), external canal and middle ear air space (10 patients), and local pneumocephalus (five patients). Evidence of brain trauma or extraaxial hematoma was seen in 12 patients. In 13 cases, high-resolution CT was also performed, demonstrating temporal bone injuries in all. This latter technique allows rapid and detailed evaluation of temporal bone trauma. Reports of radiographic evaluation of temporal bone trauma tend to deal with a somewhat skewed population, selected on the basis of clinical symptomatology. In a major trauma center equipped with high-resolution CT, it was found that temporal bone fractures may be seen incidentally, or in patients in whom symptomatology related to temporal fracture is obscured by much more serious neurologic compromise.     

High-resolution CT of the temporal bone: a modified baseline.

High-resolution computed tomography (CT) of the temporal bone, particularly axial scanning on a baseline parallel to the orbitomeatal line, produces radiation exposure to the patient's lenses. The authors evaluated the radiation dose to the lens and the visualization of temporal bone structures with use of scanning along the orbitomeatal line and on a line parallel to the hard palate. Evaluation of visualization was performed by five radiologists, with high-resolution CT scans of 45 healthy patients, and the chi 2 test was performed for comparison. The change of the baseline from the orbitomeatal line to a line parallel to the hard palate decreased the radiation dose to the lens from 12.7 cGy to 0.274 cGy and improved visualization of the stapes superstructure and the tympanic portion of the facial nerve canal, although visualization of the incus body, incudostapedial joint, lateral semicircular canal, and oval window was of equal quality. Therefore, the authors recommend a new baseline parallel to the hard palate for use at high-resolution CT of the temporal bone.     

Radiologic approach to paragangliomas of the temporal bone

High-resolution computed tomography (HRCT) has become the primary radiologic method for evaluation of paragangliomas of the temporal bone. The HRCT evaluation of the integrity of certain bony landmarks has a profound effect on selection of surgical approach. The most important landmarks are the bony walls separating the carotid artery and the jugular bulb from the middle ear. Arteriography is not necessary if the lesion is confined to the middle ear. However, it is indicated in tumors that have eroded the above landmarks or in those patients with related neurologic symptoms.     

High-resolution CT of the temporal bone in dysplasia of the auricle and external auditory canal.

PURPOSETo determine CT findings in the external, middle, and inner ear of patients with microtia and external auditory canal dysplasia.METHODSWe used high-resolution CT, with multiplanar or axial 1-mm continuous sections, coronal or sagittal reformations, or low-dose spiral acquisitions, to examine 184 temporal bones of children with microtia.RESULTSIn cases of minor microtia, auditory canal stenosis was the most common associated abnormality; in those with major microtia, atresia was predominant. Middle ear malformations depended on the severity of the auricular anomalies. Inner ear changes could also be noted. Ossicle dysplasias occurred in 98% of patients (stapes, 72%), absence of the oval window in 36%, labyrinthine malformations in 13%, closed round window in 6%, facial canal displacement in up to 75%, and aberrations of the vascular canal in 38% of patients with third-grade auricular deformity.CONCLUSIONA variety of external, middle, and, less frequently, inner ear changes were detected in connection with microtia.     

CT of the temporal bone in achondroplasia

In an attempt to better define the changes affecting the temporal bone that might predispose achondroplastic dwarfs to otitis media, nine achondroplastic subjects who were evaluated for hearing loss underwent high-resolution CT scanning of the temporal bone. Comparisons were made with 10 nonachondroplastic subjects. A number of morphologic changes were seen, including (1) poor development of mastoid air cells, (2) foreshortening of the carotid canals, (3) narrowing of the skull base, (4) "towering" petrous ridges, and (5) relative "rotation" of the cochlea and other temporal bone structures. The most significant change was the rotational effect, which was more pronounced medially, resulting in an abnormal orientation of inner ear structures relative to middle ear structures and of middle ear structures relative to the external auditory canal. There was a notable lack of evidence for otitis media or its sequelae in any of the achondroplastic subjects. Audiograms were obtained in six of the nine achondroplastic subjects (two adults and four children). There was evidence of mixed hearing loss in the four children, but only of sensorineural hearing loss in the adults. We believe that the persistent hearing loss in achondroplasia is not due to sequelae of otitis media as some authors have suggested. Intrinsic vestibulocochlear changes below the limits of resolution of high-resolution CT scanning may be responsible.     

颞骨肿块的影像学研究

目的 研究颞骨肿块的CT、MRI和DSA表现及其临床价值。方法 对照分析21例颞骨肿块的CT、MRI和DSA表现与手术病理表现。结果 5例颈静脉球瘤均显示“椒盐征”和肿瘤明显染色。3例鼓室球瘤表现为鼓室内明显强化的软组织影和肿瘤明显染色。4例内淋巴囊肿瘤CT表现为岩骨迷路后前庭水管区和中内耳软组织肿块及骨质破坏，MRI表现为“椒盐征”，T1WI示肿块边缘有环形高信号影，DSA示3例内淋巴囊腺样囊性癌明显染色。4例外中耳鳞癌CT表现为不规则软组织肿块以及中外耳广泛骨质破坏，1例DSA表现有肿瘤染色。2例软骨肉瘤CT表现为含有点片状钙化的软组织肿瘤，1例肿瘤周边可见高密度环。2例鼻咽癌侵犯中内耳，表现为岩部、鼓室、乳突和颈静脉窝不规则肿块和骨质破坏。1例嗜酸性肉芽肿CT表现为岩部、鼓室不规则肿块和骨质破坏。结论 CT和MRI清楚显示肿块的形态、范围和内部结构，能准确定位，CT、MRI和DSA结合有助于肿块的定性诊断，为手术提供依据。     

Osteoblastoma of the temporal bone: CT findings

A case of recurrent benign osteoblastoma of the temporal bone is presented with discussion of the clinical, radiological, and pathological findings. Previously reported cases of osteoblastoma of the temporal bone are briefly reviewed.     

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。     

High-resolution computed tomography of paragangliomas of the head and neck

High-resolution computed tomography with intravenous contrast enhancement is the initial procedure performed on individuals who present with signs and symptoms of a paraganglioma of the head and neck. Clinical information about these entities is reviewed and technical considerations are discussed.     

CT of the temporal bone in the CHARGE association

We reviewed the CT examinations of the temporal bone, performed with 1-mm-thick contiguous sections, of seven patients with the CHARGE association. We found abnormalities of the incus and stapes, with ossicular chain fixation, absence of the stapedius muscle and oval window, hypoplasia or dysplasia of the vestibule and absence of the semicircular canals in all ears. The pyramidal eminence and tympanic sinus were absent and there were anomalies of the cochlea in 13 of 14 ears. Absence of the semicircular canals is the most specific change in patients with the CHARGE association. Received: 4 August 1997 Accepted: 28 October 1997     

CT diagnosis of traumatic injuries of the temporal bone

73 patients with 78 fractures of the temporal bone were examined by high-resolution computed tomography (CT). Analysis of the CT-findings disclosed 55 longitudinal, 12 transverse, 8 combined and 3 atypical fractures. For determination of the fracture type, axial sections usually proved sufficient. However, for precise topographic analysis of the course of the fracture additional coronal sections were necessary in most of the cases. In the radiologic evaluation of temporal bone fractures detection of associated complications is clinically important since these can be surgically corrected. In this series 20 lesions of the ossicular chain were demonstrated by the combined performance of axial and coronal sections and sagittal reformations. High resolution CT demonstrated a lesion of the facial nerve canal in 79% of a patient group with traumatic facial nerve palsy. The most frequent site of injury of the facial nerve canal was the region of the geniculate ganglion. With the use of metrizamide-CT-cisternography the site of cerebrospinal fluid leakage was demonstrated in 7 of 9 patients with liquorrhea. It is concluded that high-resolution CT is the radiologic method of choice for both topographic evaluation of temporal bone fractures and detection and precise localization of fracture-complications.     

Experimental flat-panel high-spatial-resolution volume CT of the temporal bone

BACKGROUND AND PURPOSE: A CT scanner employing a digital flat-panel detector is capable of very high spatial resolution as compared with a multi-section CT (MSCT) scanner. Our purpose was to determine how well a prototypical volume CT (VCT) scanner with a flat-panel detector system defines fine structures in temporal bone. METHODS: Four partially manipulated temporal-bone specimens were imaged by use of a prototypical cone-beam VCT scanner with a flat-panel detector system at an isometric resolution of 150 microm at the isocenter. These specimens were also depicted by state-of-the-art multisection CT (MSCT). Forty-two structures imaged by both scanners were qualitatively assessed and rated, and scores assigned to VCT findings were compared with those of MSCT. RESULTS: Qualitative assessment of anatomic structures, lesions, cochlear implants, and middle-ear hearing aids indicated that image quality was significantly better with VCT (P < .001). Structures near the spatial-resolution limit of MSCT (e.g., bony covering of the tympanic segment of the facial canal, the incudo-stapedial joint, the proximal vestibular aqueduct, the interscalar septum, and the modiolus) had higher contrast and less partial-volume effect with VCT. CONCLUSION: The flat-panel prototype provides better definition of fine osseous structures of temporal bone than that of currently available MSCT scanners. This study provides impetus for further research in increasing spatial resolution beyond that offered by the current state-of-the-art scanners.     

Histiocytosis X of the temporal bone: CT findings

The preoperative diagnosis of temporal bone histiocytosis X has been based traditionally on clinical examination, plain radiography, and pluridirectional tomography. Clinical misdiagnosis is common because otologic findings can mimic those of acute and chronic infectious ear disease. Similarly, plain radiographic and tomographic findings may be confused with those of mastoiditis, cholesteatoma, and temporal bone metastasis. The three cases of histiocytosis X presented here illustrate the advantages of CT compared with traditional radiographic methods in the diagnosis and staging of this disease. Computed tomography clearly delineates osseous involvement, including erosion of the bony labyrinth. Computed tomography also better defines the soft tissue margins of the granulomatous mass in relationship to the central nervous system and extratemporal tissues.     

Direct sagittal CT in the evaluation of temporal bone disease

The human temporal bone is an extremely complex structure. Direct axial and coronal CT sections are quite satisfactory for imaging the anatomy of the temporal bone; however, many relationships of the normal and pathologic anatomic detail of the temporal bone are better seen with direct sagittal CT sections. The sagittal projection is of interest to surgeons, as it has the advantage of following the plane of surgical approach. This article describes the advantages of using direct sagittal sections for studying various diseases of the temporal bone. The CT sections were obtained with the aid of a new head holder added to our GE CT 9800 scanner. The direct sagittal projection was found to be extremely useful for evaluating diseases involving the vertical segment of the facial nerve canal, vestibular aqueduct, tegmen tympani, sigmoid sinus plate, sinodural angle, carotid canal, jugular fossa, external auditory canal, middle ear cavity, infra- and supralabyrinthine air cells, and temporomandibular joint.