High-resolution petrous bone imaging using multi-slice computerized tomography

Multi-slice computerized tomography (MSCT) is considered to provide superior image quality. We defined a data acquisition protocol for high-resolution (HR) temporal bone imaging using MSCT and assessed its impact on data acquisition and post-processing (PP). The data acquisition protocol was defined in cadaveric phantom studies performed by MSCT and subsequently applied to 38 patients referred for temporal bone assessment. The parameters image quality and diagnostic value of MSCT data were assessed for the cross-sectional source images as well as for 2-dimensional (2D) reformations and 3-dimensional (3D) reconstructions by 3 radiologists by comparison with incremental HR scans of 17 patients with suspected middle ear disorders. The data acquisition protocol yielded HR images with an excellent detail resolution and a comparable image quality of cross-sectional scans and related orthogonal reformations. MSCT achieved higher scores for image quality and diagnostic value (p < 0.001, t-test) than incremental HR CT with regard to both 2D and 3D reconstructions. MSCT improves the image quality of HR cross-sectional scans as well as that of 2D and 3D PP techniques in petrous bone imaging. The radiation exposure of the eye lenses is increased by MSCT as gantry angulation is not yet possible in the helical scan mode.     

How to reliably evaluate middle ear diseases? Comparison of different methods of post-processing based on multislice computed tomography examination

CONCLUSIONS: Multislice computed tomography (MSCT) virtual endoscopy was useful in evaluating mainly post-traumatic and postoperative cases. In other pathological conditions axial images and MPR reformations were most useful. OBJECTIVES: Evaluation of cross-sectional images, multiplanar 2-D reformations, 3-D reconstructions and virtual endoscopy (VE) in assessment of the middle ear in inflammatory diseases, trauma, otosclerosis and tumours. Comparison of each method and correlation with surgical findings. MATERIALS AND METHODS: Investigations were carried out in 80 patients with middle ear pathology. In each case MSCT of the petrous bone was performed. In addition to cross-sectional native scans, frontal and sagittal images were achieved using MPR reconstructions. 3-D volume rendering (VR) and VE images were also generated. The value of native scans information, 2-D, 3-D reconstructions and VE of the tympanic cavity structures was assessed in comparison to intraoperative findings. RESULTS: MPR reconstructions were most useful in the assessment of skull base trauma, skull base tumours and in cases of chronic middle ear inflammation. Highly vascularized tumours, disruption of ossicular chain and stapes prosthesis were best evaluated on 3-D reconstructions. Axial images proved to be the best for otosclerosis interpretation.     

Preoperative imaging of chronic sinusitis by multislice computed tomography

The aim of this study was to evaluate whether multislice CT enables quality improvement and dose reduction in the imaging of the paranasal sinuses, especially when using secondary reconstructions. We compared the imaging quality of direct CT scans and secondary reconstructions of single-slice CT (SSCT) as a criterion standard with multislice CT (MSCT) of the paranasal sinuses in 80 patients suspected of having chronic sinusitis. Coronary secondary reconstructions were calculated from all transversal CT data sets. Coronary reconstructions of transversal MSCT showed a significantly better image quality compared with coronary reconstructions of SSCT. Because of the absence of dental metal artifacts, coronary reconstructions of MSCT were superior even to direct coronary images of SSCT. MSCT offered a superior examination quality compared to SSCT. A halving of radiation dosage can be reached by eliminating one examination plane.     

A post-processing protocol for three-dimensional visualization of the inner ear using the volume-rendering technique based on a standard magnetic resonance imaging protocol.

A superior diagnostic quality compared to other post-processing (PP) techniques for three-dimensional (3D) inner ear imaging has been attributed to volume rendering (VR). We defined and assessed a VR protocol for 3D visualization of the inner ear in a routine imaging setting. Following definition of a VR protocol by using lower threshold values, surface shading, perspective views and related parameters, standardized 3D views of the inner ear were generated and evaluated in 32 patients suffering from sensorineural or combined hearing loss. Comprehensive inner ear visualization was achieved in 28 patients by means of two 3D shaded-surface views. Incomplete data acquisition (1/32), motion and pulsation artefacts (2/32) and interposed fluid-retaining mastoid cells (1/32) were responsible for non-diagnostic image quality in 4/32 patients. In 5/32 patients modifications of the PP protocol involving the threshold value and depth-cueing parameters helped to establish diagnostic image quality. Mean post-processing time amounted to 5.8 min per site. 3D imaging with the VR technique is suitable for routine inner ear assessment if direct VR, predefined PP protocols and standardized labyrinthine views are used.     

A Post-processing Protocol for Three-dimensional Visualization of the Inner Ear Using the Volume-rendering Technique Based on a Standard Magnetic Resonance Imaging Protocol

A superior diagnostic quality compared to other post-processing (PP) techniques for three-dimensional (3D) inner ear imaging has been attributed to volume rendering (VR). We defined and assessed a VR protocol for 3D visualization of the inner ear in a routine imaging setting. Following definition of a VR protocol by using lower threshold values, surface shading, perspective views and related parameters, standardized 3D views of the inner ear were generated and evaluated in 32 patients suffering from sensorineural or combined hearing loss. Comprehensive inner ear visualization was achieved in 28 patients by means of two 3D shaded-surface views. Incomplete data acquisition (1/32), motion and pulsation artefacts (2/32) and interposed fluid-retaining mastoid cells (1/32) were responsible for non-diagnostic image quality in 4/32 patients. In 5/32 patients modifications of the PP protocol involving the threshold value and depth-cueing parameters helped to establish diagnostic image quality. Mean post-processing time amounted to 5.8 min per site. 3D imaging with the VR technique is suitable for routine inner ear assessment if direct VR, predefined PP protocols and standardized labyrinthine views are used.     

Virtual rendering techniques in otologic imaging

Virtual postprocessing techniques combine the advantages of condensing the large amounts of data provided by high-resolution (HR) cross-sectional imaging modalities with those of three-dimensional (3D) imaging. The techniques and indications for virtual representations in imaging of the middle ear (ME), internal ear (IE), and cerebellopontine angle (CPA) are presented together with practical examples. MATERIAL AND METHODS: HR data sets acquired by computed tomography (CT) and magnetic resonance imaging (MRI) in patients with ME, IE, and CPA pathologies were transferred to a workstation via an internal network to generate endo- or extraluminal 3D views by means of the volume rendering technique (VRT). The source data were acquired using scanners and imaging protocols with the highest resolution available at present: a multislice spiral CT (MSCT) with a slice thickness of 0.5 mm and a reconstruction increment of 0.2 mm and a 3D CISS sequence with a slice thickness of 0.5 mm for MRI. RESULTS: Virtual endoscopy was superior to cross-sectional images for assessing ME pathologies like dysplasia, postoperative changes, and destructive bone processes with extensive soft-tissue involvement; fibrous obliterations of the internal ear and labyrinthine dysplasia were depicted with a superior image quality on 3D renderings compared to conventional reconstruction techniques. Virtual endoscopy of the CPA and external acoustic meatus (EAM) was helpful in detecting and visualizing neurovascular conflicts and in assigning small intrameatal tumors to components of the acousticofacial bundle. A common feature of all applications was that the large numbers of source images could be reduced to a few 3D reconstructions for documentation and optimized communication of the findings between the radiologist and otologist. CONCLUSION: Virtual rendering makes an important contribution towards establishing, presenting, and documenting the findings when certain otologic pathologies have to be assessed. It can be used for routine imaging and allows for more efficient handling of the large amounts of imaging data generated by high-resolution cross-sectional imaging modalities.     

Three-dimensional imaging of the inner ear by volume-rendered reconstructions of magnetic resonance data

OBJECTIVE: To evaluate 3-dimensional inner ear visualization by volume rendering of high-resolution magnetic resonance data in patients with clinically suspected inner ear abnormality. DESIGN: Prospective comparative study of different postprocessing techniques, based on blinded film readings. SETTING: Tertiary referral hospital. SUBJECTS: Fifty patients (17 females and 33 males) aged 1 to 77 years (average age, 42 years) with sensorineural hearing loss, vertigo, and/or tinnitus. INTERVENTION: Postprocessing of magnetic resonance data to inner ear reconstructions by the use of volume rendering as well as maximum-intensity projection; caloric testing by electronystagmography. MAIN OUTCOME MEASURES: Film was read blindly by 4 radiologists using a 5-point parameter scale for image quality and diagnostic value. The assessibility of inner ear subsegments was evaluated. The specificity of volume-rendered reconstructions for detecting semicircular canal obliterations was assessed in a subgroup of 9 patients by caloric testing. The time required for data postprocessing as well as film reading was recorded by means of a stopwatch. RESULTS: Volume-rendered inner ear reconstructions were superior in image quality (P<.001), diagnostic value (P<.001), subsegment inner ear assessment (P<.01 to P<.001), and film reading time (P<.001) compared with maximum-intensity projections. The data postprocessing time was comparable for both techniques. Caloric weakness was noted in all patients assessed by electronystagmography. CONCLUSION: Volume rendering is the postprocessing technique of choice for 3-dimensional inner ear visualization, performing better than maximum-intensity projections with respect to various parameters.     

Virtual laryngoscopy

Virtual endoscopy enables computer-generated 3-dimensional visualization of a cavity by reconstructing 2-dimensional computed tomographic or magnetic resonance data. The technique has been used experimentally to study the colon, bronchi, ears, and other structures. Here, virtual laryngoscopies were created from the cross-sectional image data of 3 patients. The cases represented a normal airway, a squamous cell carcinoma of the glottic fold, and a posterior glottic stenosis. These reconstructions included extraluminal anatomy that is not typical of current virtual endoscopic techniques. The 2-dimensional computed tomographic and magnetic resonance images of the patients underwent post-processing for 3-dimensional reconstruction. The resulting models were imported into an experimental virtual endoscopy program for 1) airway lumen generation and 2) interactive viewing. Though they could not be used for biopsy, the virtual laryngoscopies provided, in a noninvasive fashion, good simulation of endoscopy. Virtual endoscopy also gave the added benefits of the ability to assess the transmural extent of disease and view the airway distal to areas of luminal compromise. This technology may well provide clinical benefit in preoperative planning, staging, and intraprocedural guidance for head and neck disease and merits further study.     

An experimental study for qualitatively diagnosing stapes lesions by helical 3-dimensional CT

To evaluate qualitative diagnosis of stapes lesions by 3-dimensional computed tomography (3D-CT) combined with superselective image processing (3D-SS) of stapes, we studied helical 3D-CT on a phantom model of the temporal bone. Two stapes models were used-1 made from the bone filler, Celatite, consistent in bone density but changing in cross sectional area, and the other made from an apacerum rod used in quantitative computed tomography (QCT), consistent in cross sectional area but changing in bone density. These stapes models were put into a skull phantom and analyzed by helical 3D-CT. The influence of the tympanic cavity conditions on CT images of stapes was evaluated by filling the phantom model with Vaseline following 3D selective reconstruction. In all stapes models, lowering the lower CT window width threshold resulted in an enlarged cross-sectional area of the model. The higher the bone density, the lower the increase in cross-sectional area in the image. The stapes model with lower density had greater influence on the imaging by tympanic cavity conditions and was likely to be misdiagnosed as showing higher bone density. Based on the experimental study, 3D-SS by helical 3D-CT appears to be a useful measure for qualitatively diagnosing stapes lesions.     

Validation of a novel imaging approach using multi-slice CT and cone-beam CT to follow-up on condylar remodeling after bimaxillary surgery

The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography (MSCT) and postoperative cone-beam computed tomography (CBCT) images. Second, the reliability and accuracy of this condylar volume quantification method was assessed. The mandibles of 20 patients (11 female and 9 male) who underwent bimaxillary surgery were semi-automatically extracted from MSCT/CBCT scans and rendered in 3D. The resulting condyles were spatially matched by using an anatomical landmark-based registration procedure. A standardized sphere was created around each condyle, and the condylar bone volume within this selected region of interest was automatically calculated. To investigate the reproducibility of the method, inter- and intra-observer reliability was calculated for assessments made by two experienced radiologists twice five months apart in a set of ten randomly selected patients. To test the accuracy of the bone segmentation, the inner and outer bone structures of one dry mandible, scanned according to the clinical set-up, were compared with the gold standard, micro-CT. Thirty-eight condyles showed a significant (P＜0.05) mean bone volume decrease of 26.4%±11.4% (502.9 mm3±268.1mm3). No significant effects of side, sex or age were found. Good to excellent(ICC＞0.6) intra- and inter-observer reliability was observed for both MSCT and CBCT. Moreover, the bone segmentation accuracy was less than one voxel (0.4mm) for MSCT (0.3 mm±0.2 mm) and CBCT (0.4 mm±0.3 mm), thus indicating the clinical potential of this method for objective follow-up in pathological condylar resorption.     

Virtual reality modelling language: freely available cross-platform visualization technique for 3-D visualization of the inner ear

This was a study of the use of virtual reality modelling language (VRML) for cross-platform interactive three-dimensional (3-D) visualization of high-resolution magnetic resonance (MR) images of the inner ear in the assessment of cochlear implant candidates. A retrospective case review was made of cochlear implant candidates undergoing pre-operative high-resolution MR studies to determine their suitability for implantation. 3-D visualizations of MR scans of the inner ear structures were created using surface rendering and exported as portable VRML files. Case studies are presented to illustrate different points of interest. VRML reconstructions aided the interpretation of two-dimensional (2-D) source images in a variety of inner ear abnormalities. VRML is an internationally recognized standard for cross-platform 3-D visualization that creates a means of providing the implanting surgeon with a portable 3-D representation of the inner ear, aiding interpretation of the complex cross-sectional anatomy of these structures, and guiding selection of patients for implantation as well as implantation technique. The elucidation of the mechanisms behind inner ear malformations can also be aided by detailed imaging studies of the temporal bone, with VRML reconstructions providing an easily interpreted representation of deformities.     

多层螺旋CT对先天性内耳发育畸形的诊断价值

目的探讨多层螺旋CT(multi-slice computed tomography，MSCT)对先天性内耳发育畸形的诊断价值。方法对44例先天性感音神经性聋患者做MSCT横断面螺旋方式扫描及多平面重建(multi-planar reformation，MPR)，必要时做单侧重叠放大重建，并利用容积漫游技术(volume rendering technique，VRT)对骨迷路进行三维重建。结果44例患者中25例CT表现正常，19例(36耳)表现为内耳发育畸形。畸形有以下几种：Michel型(1耳次)，共同腔畸形(3耳次)，不完全分隔Ⅰ型(3耳次)，不完全分隔Ⅱ型(Mondini型，5耳次)，前庭及半规管畸形(14耳次)，前庭导水管扩大(16耳次，其中6耳次伴随其他畸形)，内耳道畸形(8耳次均伴随其他畸形)。36耳畸形中33耳MSCT横断面图像和MPR图像、VRT图像均可以清晰的显示畸形的部位和程度，其中VRT图像可以直观、立体地显示畸形的空间形态结构；3耳水平半规管短小畸形患者VRT图像较断面图像更好的显示了畸形的部位和程度。结论MSCT提高了横断面图像以及MPR、VRT图像的空间分辨率。VRT图像直观、立体的显示了骨迷路畸形的空间形态结构，并且可以通过旋转多方位观察畸形的形态。MSCT扫描结合VRT可更加准确的对内耳骨迷路畸形的部位和程度做出诊断，加深了我们对各种畸形的理解，有助于人工耳蜗植入手术计划的制定。     

多层螺旋CT在闭合性甲状软骨损伤诊断中的价值

目的 探讨多层螺旋CT(multi-slice spiral computed tomography,MSCT)扫描在闭合性甲状软骨损伤诊断中的成像方法及应用价值.方法 对闭合性甲状软骨损伤5例患者进行MSCT扫描,重建数据在Advantage Workstation 4.0工作站进行二维、三维图像处理.其中联合应用多平面重组(multi-planar reconstruction,MPR)4例次,容积重建(3D-volume reconstruction,3D-VR)3例次,仿真喉镜成像(computed tomography virtual laryngoscope,CTVL)1例次.结果 5例患者中发现甲状软骨左板骨折4例,右板骨折1例;其中合并环状软骨骨折1例,合并上气道狭窄1例.利用窄窗宽低窗位技术有助于显示软骨结构,本组4例利用MPR图像进行多角度观察,对显示骨折线的走行及移位能取得满意的效果.3例利用3D-VR图像显示软骨结构的空间改变,其立体效果能为临床医牛选择治疗方案提供依据.1例运用CTVL技术对上气道狭窄及狭窄程度做出明确诊断.结论 MSCT扫描能够清晰地显示闭合性甲状软骨骨折及上气道狭窄,选择合适的后处理技术或多种技术联合运用能够提供准确、直观的图像.     

Development of the mouse cochlea database (MCD)

The mouse cochlea database (MCD) provides an interactive, image database of the mouse cochlea for learning its anatomy and data mining of its resources. The MCD website is hosted on a centrally maintained, high-speed server at the following URL: http://mousecochlea.umn.edu. The MCD contains two types of image resources, serial 2D image stacks and 3D reconstructions of cochlear structures. Complete image stacks of the cochlea from two different mouse strains were obtained using orthogonal plane fluorescence optical microscopy (OPFOS). 2D images of the cochlea are presented on the MCD website as: viewable images within a stack, 2D atlas of the cochlea, orthogonal sections, and direct volume renderings combined with isosurface reconstructions. In order to assess cochlear structures quantitatively, "true" cross-sections of the scala media along the length of the basilar membrane were generated by virtual resectioning of a cochlea orthogonal to a cochlear structure, such as the centroid of the basilar membrane or the scala media. 3D images are presented on the MCD website as: direct volume renderings, movies, interactive QuickTime VRs, flythrough, and isosurface 3D reconstructions of different cochlear structures. 3D computer models can also be used for solid model fabrication by rapid prototyping and models from different cochleas can be combined to produce an average 3D model. The MCD is the first comprehensive image resource on the mouse cochlea and is a new paradigm for understanding the anatomy of the cochlea, and establishing morphometric parameters of cochlear structures in normal and mutant mice.     

3D printed temporal bone as a tool for otologic surgery simulation

PurposeIn this face validity study, we discuss the fabrication and utility of an affordable, computed tomography (CT)–based, anatomy-accurate, 3-dimensional (3D) printed temporal bone models for junior otolaryngology resident training.Materials and methodsAfter IRB exemption, patient CT scans were anonymized and downloaded as Digital Imaging and Communications in Medicine (DICOM) files to prepare for conversion. These files were converted to stereolithography format for 3D printing. Important soft tissue structures were identified and labeled to be printed in a separate color than bone. Models were printed using a desktop 3D printer (Ultimaker 3 Extended, Ultimaker BV, Netherlands) and polylactic acid (PLA) filament. 10 junior residents with no previous drilling experience participated in the study. Each resident was asked to drill a simple mastoidectomy on both a cadaveric and 3D printed temporal bone. Following their experience, they were asked to complete a Likert questionnaire.ResultsThe final result was an anatomically accurate (XYZ accuracy = 12.5, 12.5, 5 μm) 3D model of a temporal bone that was deemed to be appropriate in tactile feedback using the surgical drill. The total cost of the material required to fabricate the model was approximately $1.50. Participants found the 3D models overall to be similar to cadaveric temporal bones, particularly in overall value and safety.Conclusions3D printed temporal bone models can be used as an affordable and inexhaustible alternative, or supplement, to traditional cadaveric surgical simulation.     

In vivo measurements of temporal bone on reconstructed clinical high-resolution computed tomography scans

PURPOSE: To retrospectively assess the accuracy of measurements of temporal bone anatomy made from reconstructed clinical high-resolution computed tomography (HRCT) scans. METHODS: Nine HRCT scans were performed on unselected clinical cases in which the subjects had a temporal bone study judged to be normal. The orbitomeatal line was prescribed for the direct axial sections. Variations in head position (rotation at the neck and lateral bending of the neck) were corrected by using the software supplied by the manufacturer. All measurements were done on standard 1-mm axial sections and axial reconstructions obtained from 1-mm coronal slices. The images were viewed at 4000 Hounsfield units (HU) window width and 1000 HU window level. Measurements (n = 3) made on 1-mm direct axial HRCT scans were compared with the measurements made on reconstructed axial HRCT images from the same nine patients. These values were also compared with published cadaver data. RESULTS: The measurements obtained from axial reconstructed and direct HRCT series approximated each other in each of the nine individual studies and also fell within the range of published cadaver values. They demonstrated the expected normal temporal bone variability between individuals. CONCLUSION: Useful anatomic approximations can be measured in vivo from reconstructed clinical HRCT images. Pitfalls are improper window settings, head tilt, and rotation. This protocol is widely available and can be implemented retrospectively from clinical HRCT scans.     

How best to present the radiological picture of the temporal bone today?

The detailed evaluation of anatomy and pathology of the temporal bone requires imaging modalities that are superior to plain x-ray films. Conventional polytomography has today largely been replaced by high-resolution CT. High-resolution CT provides excellent demonstration of the delicate bony structures and provides superior information about the soft tissues. The axial 1 mm scans of a complete temporal bone examination can be reformated in any number of planes. These reconstructions display the temporal bone in various projections. This theoretically well-founded procedure of individual processing has proven to be highly practical in more than 1000 examinations of the skull base. High-resolution CT with image reconstruction is the diagnostic method of choice for the evaluation of the skull base and especially the temporal bone, as the complex anatomy is best demonstrated by this technique. Six axial computed tomographic scans are demonstrated in detail. The special value of multiplanar reconstructions is illustrated by reconstructions in the coronal, sagittal and longitudinal plane.     

Rationelle CT-Diagnostik vor Operationen an den Nasennebenhöhlen

Movement or metal artefacts as well as the relatively high radiation exposure of both the axial and the coronal scan are disadvantages of computed tomography. A single spiral CT scan with a secondary reformation replacing the second CT scan might solve these problems. The goal of this project was to compare the diagnostic value of primary spiral CT scans of paranasal sinuses with secondary reformations. These were evaluated by ENT surgeons as well as radiologists. We performed axial and coronal spiral-CT's of paranasal sinuses in 80 patients. The secondary coronal and axial reformations were calculated with 2 mm image sections. Although a reduced resolution was observed in the secondary reformations, this did not compromise the detection of important anatomical features. Image deterioration due to artifacts was significantly reduced.     

Differences of radiological artefacts in cochlear implantation in temporal bone and complete head

Abstract

Objectives

Accurate radiological evaluation of cochlear implants is essential for improvement of devices and techniques and also for assessing the position of the electrodes within the cochlea. Radiological study of implants has focused on isolated temporal bones. Previous studies showed relevant sizes of artefacts (dimensions of the radiological image compared with the actual dimensions of the electrode) in visualization of cochlear implants in computed tomography and cone beam computed tomography (CBCT). In this study, we aimed to obtain CBCT images of cochlear electrodes in isolated temporal bones and in whole heads and to assess the differences in image quality between the two.

Methods

Cochlear electrodes were implanted in three complete human heads. Radiological examinations were performed using a single CBCT scanner with varying x-ray tube currents, voltages, and rotation angles. The temporal bones were then removed and the same radiological examinations were repeated, with and without the receiver coils. Artefacts from a basal electrode (electrode 9) and an apical electrode (electrode 2) were calculated. These were compared with each other by measuring the diameter of the image of the electrode (electrode inclusive of imaging artefacts) and with the real electrode diameters from the manufacturer's data. Additionally, the radiological diameters (inclusive of artefact) of the electrodes were compared to the cross-sectional diameters of the basal and apical coils of the cochlea at the locations of these two electrodes.

Results

In comparison to the real electrode diameters, radiological artefact proportions of 51–58% for electrode 9 and 56–61% for electrode 2 were calculated. The differences between whole head images (group 1) and temporal bone images with and without the receiver coil (groups 2 and 3) were highly significant for each protocol (P < 0.001).

Discussion and conclusion

These results indicate that it is not possible reliably to determine the exact intracochlear positions of electrodes using CBCT. Imaging of isolated temporal bones produced significantly greater artefacts than imaging of the whole head. Evaluations of image quality based only on results for isolated temporal bones are not transferable to clinical situations, and should be assessed critically.     

Three-dimensional CT scan reconstruction for the assessment of congenital aural atresia.

Major advances in medical computer graphics workstations have provided the capability to produce high quality three-dimensional image reconstructions from conventional thin-section computerized tomography (CT) scans with the ability to observe the imaged structure from any angle, with views and dimensions that are comparable to actual dissections. We have applied this technique to the temporal bone to assess congenital aural atresia in surgical planning for hearing reconstruction in six patients. The digital information produced by thin-section CT scanning allowed for the re-creation of multiplanar reformatted, shaded surface, and volumetric images. With this technique the surface landmarks of the temporal bone were readily visualized, the configuration of the atretic plate and middle ear in relation to the tegmen and glenoid fossa could be precisely assessed and the structure of the ossicular mass was easily analyzed. Most significantly, the facial nerve could be accurately and easily envisioned in its entire intratemporal course. Three-dimensional imaging is a highly desirable means for observing CT scan data to facilitate the surgical planning for correction of congenital aural atresia.