Axial High-resolution Computed Tomography Research Articles

Menière's Syndrome Associated With Fibrous Dysplasia of the Temporal Bone.

Menière's Syndrome Associated With Fibrous Dysplasia of the Temporal Bone.

Predictors of round window membrane visibility in pediatric cochlear implant surgery using temporal bone HRCT: A retrospective study

ObjectiveTo predict round window membrane (RWM) visibility and electrode insertion sites using high-resolution computed tomography (HRCT) in pediatric cochlear implant surgery. Materials and methodsSixty-two ears of 36 infants less than 1 year old were included in our study. Intraoperative RWM visibility was classified into three types corresponding to three different surgical approaches. Radiologic parameters were measured on preoperative axial temporal HRCT images and correlated with RWM visibility and surgical approaches. ResultsA significant correlation was found between the degree of RWM visibility and the following two parameters: 1) a line (lw) was drawn from the posterior margin of the RWM to the intersection point of the posterior wall of the external auditory canal (EAC) and mastoid cortex. Another line (lf) was drawn between the posterior margin of the RWM and the lateral margin of the FN. The angle between lw and lf was measured as angle A, P < 0.01, R2 = −0.809; 2) a line (lm) was drawn from the anterior to posterior margin of the RWM, and the angle between lm and lf was measured as angle B, P < 0.01, R2 = −0.850. A nonsignificant correlation was found between the degree of RWM visibility and the facial recess width, p > 0.05, R2 = −0.00015. ConclusionRWM visibility showed a high correlation with the two angular measurements (angle A and angle B) and was associated with electrode insertion sites. In children less than one year old, surgeons can depend on those two parameters in predicting the RWM visibility.

Reduced area of the normal lung on high-resolution computed tomography predicts poor survival in patients with lung cancer and combined pulmonary fibrosis and emphysema.

This study aimed to determine the radiologic predictors and clarify the clinical features related to survival in patients with combined pulmonary fibrosis and emphysema (CPFE) and lung cancer. We retrospectively reviewed the medical chart data and high-resolution computed tomography (HRCT) findings for 81 consecutive patients with CPFE and 92 primary lung cancers (70 men, 11 women; mean age, 70.9 years). We selected 8 axial HRCT images per patient, and visually determined the normal lung, modified Goddard, and fibrosis scores. Multivariate analysis was performed using the Cox proportional hazards regression model. The major clinical features were a high smoking index of 54.8 pack-years and idiopathic pulmonary fibrosis (n = 44). The major lung cancer profile was a peripherally located squamous cell carcinoma (n = 40) or adenocarcinoma (n = 31) adjacent to emphysema in the upper/middle lobe (n = 27) or fibrosis in the lower lobe (n = 26). The median total normal lung, modified Goddard, and fibrosis scores were 10, 8, and 8, respectively. TNM Classification of malignant tumors (TNM) stage I, II, III, and IV was noted in 37, 7, 26, and 22 patients, respectively. Acute exacerbation occurred in 20 patients. Multivariate analysis showed that a higher normal lung score and TNM stage were independent radiologic and clinical predictors of poor survival at the time of diagnosis of lung cancer. A markedly reduced area of normal lung on HRCT was a relevant radiologic predictor of survival.

Relationship between interstitial lung disease and oesophageal dilatation on chest high-resolution computed tomography in patients with systemic sclerosis: a cross-sectional study.

Oesophageal dilatation (OD) has been implicated in the pathogenesis of interstitial lung disease (ILD) in systemic sclerosis (SSc). The aims of this study were to explore the association of the OD and SSc-ILD on chest high-resolution computed tomography (HRCT), and to establish a cutoff point for the OD suggestive for the presence of a significant lung involvement. The widest oesophageal diameter (WOD) was obtained on axial HRCT images. The parenchymal abnormalities on HRCT were coded and scored according to Warrick method. Patient-centred measures, pulmonary function tests and the single breath carbon monoxide diffusing capacity of the lung (DLco) were also obtained. Multivariate regression analysis was performed to identify factors associated with oesophageal diameter. 126 subjects with SSc were included. The mean (± SD) WOD was 13.5 (± 4.2) mm, and in 76 (60.3%) participants WOD was ≥ 11mm. SSc patients with ILD had larger oesophageal diameters than those without lung disease (19.4 vs. 14.1mm, p < 0.001). We observed a high correlation between WOD and gastro-oesophageal reflux disease questionnaire (GerdQ) (r = 0.886, p < 0.001), Borg score (r = 0.705, p < 0.001), and Warrick score (r = 0.614, p < 0.001). WOD negatively correlated with DLco (r = - 0.508, p < 0.001). Multivariate analysis demonstrated positive associations between WOD and GerdQ (p < 0.0001), Borg score (p < 0.0005), and total Warrick score (p = 0.019). An increased oesophageal diameter (> 11mm) on chest HRCT is associated with pulmonary and oesophageal symptoms, more severe ILD, and lower DLco.

Agreement Between High-Resolution Computed Tomography and Pathological Tumor Size of Lung Adenocarcinoma: Influence of Ground Glass Opacity Ratio

Objectives: To compare the tumor size of lung adenocarcinoma manifesting as sub-solid nodule (SSN) as measured by high-resolution computed tomography (HRCT) and pathological specimens, and to analyze the influence of ground glass opacity (GGO) ratio on the discrepancy between HRCT and pathological measurements. Patients and Methods: Fifty-five patients diagnosed with lung adenocarcinoma manifesting as SSN on HRCT were retrospectively analyzed. The pathological lesion size was 3 cm or less in the largest dimension. The largest diameter of the lesion and the largest diameter of the solid component were measured on axial HRCT scans by two radiologists. Simultaneously, the largest diameter of the lesion was also determined using computer-aided software, and GGO ratio was calculated. The correlation of GGO ratio with the discrepancy between HRCT tumor size and pathological tumor size was analyzed using Pearson’s/Spearman’s rank correlation tests. Results: GGO ratio was well correlated with the discrepancy of tumor size between manual and pathological measurements and between semi-automatic and pathological measurements, with the correction coefficient of 0.474 and 0.457, respectively. Conclusion: GGO ratio is correlated with the discrepancy between HRCT tumor size and pathological tumor size. These finding provides insights into clinical treatment and prognosis judgment of lung adenocarcinoma manifesting as SSN.

Role of Multislice CT Imaging in Predicting the Visibility of the Round Window in Pediatric Cochlear Implantation.

High-resolution computed tomography (HRCT) magnifies the role of preoperative imaging for detailed inner and middle ear anatomical information and enhances more efforts for better dependent correlation and measurements of round window (RW). To find an applicable way by HRCT imaging for the prediction of the visibility of the RW during cochlear implantation (CI) surgery. Five radiologic measurements were performed on the axial HRCT and these measurements were correlated with the degree of RW visibility after performing posterior tympanotomy during CI surgery. Sixty ears of 60 children were included in the current study. A significant correlation was found between the degree of RW visibility and the following: 1) the angle between RW, facial nerve (FN), and the coronal axis (p < 0.00001); 2) the vertical distance between RW and FN (p = 0.006552); and 3) FN location to the axis of cochlea (p = 0.000419). On the other hand, nonsignificant correlation was found between the degree of RW visibility and both of the facial recess width and the angle between axis of cochlea and external auditory canal (p = 0.941363 and p = 0.59036 respectively). The angle between RW, FN, and the coronal axis and the vertical distance between RW and FN are proportionate with the degree of surgical RW visibility in children during CI. In children, surgeons can depend on those two parameters in addition to the distance between FN location to the axis of cochlea in predicting the RW visibility rather than depending on the measurements related to the external auditory canal.

Prediction of round window visibility in cochlear implantation with temporal bone high resolution computed tomography

Objective: To discuss the prediction of round window(RW) visibility in cochlear implantation(CI) with temporal bone high resolution computed tomography(HRCT). Methods: From January 2013 to January 2017, 130 cases underwent both HRCT and CI in our hospital were analyzed. The distance from facial nerve to posterior canal wall(FWD), the angle between facial nerve and inner margin of round window(FRA), and the angle between facial nerve and tympanic anulus to inner margin of round window(FRAA) were detected at the level of round window on axial temporal bone HRCT. A line parallel to the posterior wall of ear canal was drawn from the anterior wall of facial nerve at the level of round window on axial temporal bone HRCT and its relationship with round window was detected (facial-round window line, FRL): type0-posterior to the round window, type1-between the round window, type2-anterior to the round window. Their(FWD, FRA, FRAA, FRL) relationships with intra-operative round window visibility were analyzed by SPSS 17.0 software. Results: FWD(F=18.76, P=0.00), FRA(F=34.57, P=0.00), FRAA (F=14.24, P=0.00) could affect the intra-operative RW visibility significantly. RW could be exposed completely during CI when preoperative HRCT showing type0 FRL. RW might be partly exposed and not exposed when preoperative HRCT showing type1 and type2 FRL respectively. Conclusion: FWD, FRA, FRAA and FRL of temporal bone HRCT can predict intra-operative round window visibility effectively in CI surgery.

Predicting round window niche visibility via the facial recess using high-resolution computed tomography.

To predict round window niche (RWN) visibility using high-resolution computed tomography (HRCT). Case series with chart review. Academic tertiary care center. We retrospectively reviewed 70 cochlear implant ears that underwent presurgical axial HRCT with a surgical video recorder. The visibility of the RWN was classified into three types: 17 as invisible or nearly invisible, 22 as partially visible, and 31 as fully visible. Next, we measured the following three radiologic parameters: 1) the angle of the external auditory canal (EAC) relative to the cochlear basal turn, 2) the width of the facial recess, and 3) the relative location of the facial nerve (FN) to the cochlear basal turn. These were compared with the RWN visibility. Subsequently, to predict the RWN visibility, a line was created parallel to the EAC line and along the anterior lateral FN. The location of the line relative to the round window membrane was compared with the RWN view. In cases that had poor RWN visibility, the angle of the posterior canal wall portion of the EAC relative to the cochlear basal turn was significantly smaller and the location of the FN to the cochlear basal turn was closer. The location of the prediction line to the round window membrane highly predicted the RWN view during the surgery. The RWN visibility and the preoperative HRCT findings showed a high correlation. Drawing the prediction line is a simple and useful way for preoperatively predicting the RWN visibility in cochlear implant surgery.

The feasibility of axial and coronal combined imaging using multi-detector row computed tomography for the diagnosis and treatment of a primary spontaneous pneumothorax

BackgroundThe preoperative detection of emphysema like changes (ELCs) is necessary for the successful treatment of pneumothorax. High resolution computed tomography (HRCT) has been used for the preoperative detection of ELCs. However, the traditional HRCT method uses only the axial view, which is perpendicular to the distribution of ELCs. This is not an ideal diagnostic method for the evaluation of ELCs.MethodsForty-eight patients with pneumothorax had multi-detector computed tomography (MDCT) reconstruction using the coronal view. ELCs were evaluated in the axial and coronal view by a radiologist. A surgeon performed intra-operative examinations of the ELCs. The sensitivity of the different views was compared.ResultsThe detection sensitivity was 74.4% (70/94) for the axial view and 91.5% (86/94) for the axial-coronal combined view. The intra-operative detection rate was 95.7% (90/94). The preoperative detection of ELCs on the axial-coronal combined view was significantly higher than on the conventional axial view alone (p < 0.01).ConclusionsEvaluation of ELCs on the axial and coronal combined HRCT improved the sensitivity of preoperative detection of ELCs compared to the conventional single axial HRCT. This increased sensitivity will help decrease the recurrence with VATS.

Sistematização do estudo anatômico do aqueduto vestibular por tomografia computadorizada de alta resolução em pacientes com doenças de Ménière unilateral

OBJETIVO: Sistematizar a avaliação do aqueduto vestibular por tomografia computadorizada de alta resolução (TCAR) em pacientes com doença de Ménière unilateral e comparar com um grupo-controle. MATERIAIS E MÉTODOS: Selecionamos 20 pacientes com doença de Ménière unilateral, segundo critérios da Academia Americana de Otorrinolaringologia - Cirurgia de Cabeça e Pescoço, e um grupo-controle composto por dez indivíduos com avaliação auditiva normal, totalizando 60 orelhas, distribuídas igualmente em três grupos: grupo I - doença de Ménière, orelha comprometida; grupo II - doença de Ménière, orelha não-comprometida; grupo III - controle. Submetemos os pacientes à TCAR de ossos temporais. O estudo das imagens foi feito de modo cego, procurando avaliar a visibilidade da porção descendente do aqueduto vestibular. Os dados obtidos foram correlacionados com os respectivos grupos. RESULTADOS: A visualização do aqueduto vestibular foi de 95% no grupo I, 90% no grupo II e 100% no grupo III. CONCLUSÃO: É possível sistematizar a avaliação por TCAR do aqueduto vestibular, com aquisição axial, usando a mesma técnica radiológica, conhecimento anatômico e seguimento seqüencial das estruturas da orelha interna. Com esta sistematização houve alta taxa de visualização do aqueduto vestibular, sem diferença estatisticamente significante entre os grupos.

Excessive Collapsibility of Bronchi in Bronchiectasis

To evaluate the frequency and severity of bronchomalacia, defined as excessive collapsibility of bronchi, in bronchiectasis; to compare the extent of air trapping in bronchiectasis patients with/without bronchomalacia; and to correlate the severity of bronchomalacia and the extent of air trapping versus pulmonary function. Forty-six patients with bronchiectasis evaluated by volumetric expiratory high-resolution computed tomography (CT) and pulmonary function tests were studied. The presence and severity of bronchomalacia were evaluated on contiguous axial high-resolution CT images using a 4-point scale. The extent of air trapping was graded on coronal reformations using a 5-point scale. Differences in the extent of air trapping in patients with/without bronchomalacia and the correlation between the severity of bronchomalacia and the extent of air trapping were investigated. The severity of bronchomalacia and the extent of air trapping were correlated with pulmonary function. Of 46 patients with bronchiectasis, 32 patients (70%) had bronchomalacia. Air trapping was present in 43 patients (93%). The extent of air trapping in patients with bronchomalacia was significantly greater compared with the patients without bronchomalacia (P=0.0308). The correlation between the severity of bronchomalacia and extent of air trapping was not statistically significant (rs=0.029, P=0.8457). The extent of air trapping in bronchiectasis patients with bronchomalacia was significantly greater compared with bronchiectasis patients without bronchomalacia, suggesting that the bronchomalacia is one of the underlying mechanisms of air trapping in bronchiectasis.

Sagittal reformations of volumetric inspiratory and expiratory high-resolution CT of the lung 1

The purpose of this study is to determine whether sagittal reformations of volumetric high-resolution computed tomography (CT) provide additional information in evaluating lung abnormalities compared to axial high-resolution CT images. Twenty-two consecutive patients who underwent combined inspiratory and expiratory volumetric high-resolution CT from May to July 2003 were studied. Using end-inspiratory and end-expiratory sagittal reformatted images, respiratory motion artifacts were evaluated at upper, middle, and lower lung areas bilaterally. Diaphragmatic motion artifacts were evaluated bilaterally. The detection of major and minor fissures was assessed. Additional findings on sagittal reformations were graded using a three-point scale: grade 1 = no additional findings; grade 2 = additional findings of no diagnostic significance; grade 3 = additional findings of diagnostic significance. Respiratory motion artifacts were either imperceptible or present but not diagnostically limiting except for one case, in which diagnostically limiting image degradation was noted in the bilateral lower lung areas. Diaphragmatic motion artifacts were frequently present: 95% (21/22) at end-inspiration, and 86% (19/22) at end-expiration; however, diagnostically limiting artifacts were observed in only two cases. The grading of additional findings on sagittal reformatted images was statistically significant (grade 1, n = 13; grade 2, n = 7; grade 3, n = 2; median, 1; P = .004) compared to axial images. Additional findings included relationship between mass/nodules and fissure/pleura/pericardium (grade 2, n = 4; grade 3, n = 2), distribution of interstitial abnormalities of the lung (grade 2, n = 2), and diaphragmatic eventration (grade 2, n = 1). Sagittal reformatted images of volumetric high-resolution CT provided additional information compared to volumetric axial images alone with statistical significance.

Quantitative air-trapping analysis in children with mild cystic fibrosis lung disease.

The purpose of this study was to compare quantitative computed tomography air trapping (AT) and pulmonary function measurements between subjects with mild cystic fibrosis lung disease (MCF; forced expiratory volume in 1 sec (FEV1) > 70% predicted) and normal age-matched controls. Quantitative AT measurements at different levels of expiration were evaluated. Ten subjects from the MCF group and 10 normal subjects underwent inspiratory and expiratory spirometer-triggered chest high-resolution computed tomography (HRCT) and pulmonary function tests. Six matched CT images were obtained at full inflation and at a lung volume near residual volume (nRV). Quantitative measurements of AT were determined by evaluating expiratory CT lung density and by the percent of segmented lung which demonstrated AT on expiratory scans. Percent AT was evaluated for all lung slices combined (global AT), and also by regional assessment. Additional comparisons of lung density and percent air trapping were made in 10 CF subjects with three matched axial HRCT images at lung volumes corresponding to full inflation, near functional residual capacity (nFRC), and nRV. All measurements of expiratory lung density in CF subjects were significantly lower and % AT significantly higher than normal controls. Significant correlations for all subjects were observed between % global AT and RV/TLC as well as forced expiratory flow between 25-75% of forced vital capacity (FEF(25-75)) % predicted. Pulmonary density measurements and % AT better discriminated differences between groups than PFTs. Measurements made on expiratory scans near FRC showed significantly higher values for AT than those made near RV.

Correlation of helical and incremental high-resolution thin-section computed tomographic imaging with histomorphometric quantitative evaluation of lungs in dogs.

To develop protocols for helical computed tomography (CT) and axial high-resolution CT (HRCT) of lungs and correlate densitometric CT values with morphometric and histologic data for normal pulmonary tissue in dogs. 8 healthy adult dogs. 2 dogs were used to establish a protocol for helical CT and HRCT of lungs. Six dogs were used to acquire densitometric CT data regarding normal lungs. After the dogs were euthanatized, their lungs were fixed and sampled for morphometric and histologic evaluation. Four CT acquisitions were compared by means of paired t tests. For normal lung tissue of dogs, mean densitometric CT value obtained during helical CT scans reconstructed in a sharp algorithm was -846 Hounsfield units. Values obtained via helical CT or HRCT acquisitions and reconstructed with sharp or standard algorithms did not differ significantly. Morphometric analysis was used to determine the proportion of lung parenchymal (82%) and non-parenchymal tissue (18%). Alveolar size, estimated by mean linear intercept, was approximately 172 microm, and alveolar surface area-to-volume ratio was 0.024 to 0.026 microm(-1). Histologic evaluation confirmed the presence of normal lung tissue. Correlation of densitometric CT data with morphometric and histologic findings and the establishment of helical CT and HRCT protocols were attained; clinical use of this information may facilitate investigation of pulmonary disease in dogs. Sharp helical CT acquisitions were preferred because of better lung parenchyma detail and rapid image acquisitions, compared with HRCT.

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

To retrospectively assess the accuracy of measurements of temporal bone anatomy made from reconstructed clinical high-resolution computed tomography (HRCT) scans. 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. 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. 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.

A Radiologico-Anatomical Comparative Study of the Cochlear Aqueduct

AIM: A comparative radiologico-anatomical study of the cochlear aqueduct (CA) was performed.MATERIALS AND METHODS: Eight cadavers and 23 dry temporal bones were studied. High-resolution computed tomography (HRCT) was carried out on each cadaver before microdissection. Microdissection was carried out in a plane parallel to the HRCT sections.RESULTS: The CA was found to be located an average of 7mm inferior to the internal acoustic meatus and at the superior edge of the jugular foramen. The external aperture of the CA was triangular in shape in 18 bones (78.3%). The petrosal fossa was located just inferior to the external aperture and housed the glossopharyngeal nerve, which had an incomplete bony canal in four bones (17.4%) and a complete bony canal in three bones (13%). It was possible to demonstrate the petrosal portion of the CA on both coronal and axial HRCT. The otic capsule segment of the CA was impossible to demonstrate on coronal sections.CONCLUSION: The CA cannot be visualized in only one section of the plane in HRCT. Both the otic capsule and petrosal segments can be demonstrated on axial HRCT.Tekdemir, I. (2000). Clinical Radiology55, 288–291.

An anatomical study of the tympanic branch of the glossopharyngeal nerve (nerve of Jacobson)

Our study was aimed to examine the anatomic relationships of the tympanic branch of the glossopharyngeal nerve (GPN), namely the Jacobson's nerve (JN). The JN is the first branch of the GPN after having passed the jugular foramen. It contributes to the tympanic plexus on the promontory. It transmits secretory innervation to the parotid gland. Its possible role in the regulation of the middle ear pressure has also been hypothesized in terms of animal studies. Using microdissection techniques and high-resolution computed tomography (HRCT) scanning, the anatomic relationships and course of the JN were examined in eight formalin-preserved cadavers (16 sides). A morphometric analysis related to the JN was also performed both in the 16 cadavers and 40 dry-skull specimens. The JN emerged from the inferior ganglion of the GPN in all specimens. The mean distance between the ganglion and the genu of the GPN was 11.3 mm. The inferior 2/3 of the tympanic canal (TC) followed a vertical course, and then it ran anteromedially with an angle of 160 degrees to 170 degrees. The mean length of the TC was 9.5 mm. The TC was well-defined in all axial HRCT scans. In 2 cases the JN was entirely encased in a bony canal in the middle ear. A double JN was observed in one case. This study gives an additional information regarding the anatomy of the JN.

Assessment of the dentate alveolar process with high resolution computed tomography.

The present study was undertaken to determine quantitatively the accuracy of modern high-resolution computed tomography (HR-CT) in imaging periodontal defects in vitro by means of comparative radiological and histological studies. The soft tissue and metallic restorations were removed from four mandibular and maxillary jaw segments. Eighteen lingual and buccal defects of different dimensions were artificially created over the roots of the teeth. Dental radiographs and 1.0 mm contiguous axial and coronal HR-CT scans were obtained. Histological specimens were prepared in the same plane as the CT scans. A quantitative analysis of the periodontal regions on the CT scans was feasible when the alveolar bone was 0.5 mm thick. A visible periodontal ligament space was found to improve the reliability of the measurement of buccal or lingual bone plates up to 0.2 mm thick or of the artificial dehiscences. In the axial HR-CT scans, 70% of the artificial defects could be identified. and in the coronal scans, 50%. In contrast, none of the defects could be evaluated on conventional dental radiographs. It is concluded that HR-CT scanning could be useful in assessing buccal and lingual alveolar bone morphology and in diagnosing larger dehiscences.

Acquired disruptions of the incudostapedial articulation: diagnosis with CT.

To determine the best technique for diagnosing incudostapedial joint disruption with computed tomography (CT), the authors reviewed 15 surgically proved cases. In each case, the articulation was depicted on axial but not coronal images. Disruption was due to inflammation in ten cases and trauma in five. Axial high-resolution CT is valuable in the diagnosis of traumatic and inflammatory disruption of the incudostapedial joint.

高分解能ＣＴによる後部鼓室病変の診断

The posterior tympanum consists of several irregular eminences, ridges, and sinuses. These sinuses do not communicate with the mastoid air cell system, and cholesteatoma and/or granulation tissue prefer to fill them. This area cannot be visualized with ease by the usual surgical approach, and is thus quite important for surgeons. Recent developments in high-resolution computed tomography (HRCT) allow more than ever precise identification of subtle changes in the posterior tympanum. Axial HRCT sections provide essential information for the preoperative evaluation of the posterior tympanum. The performance of surgeons has been promoted both in evaluation and treatment planning of patient with suspected posterior tympanic lesions. HRCT findings were compared with the operative findings in 52 patients (54 ears) who had the operation for chronic otitis media. Important findings by HRCT diagnosis of posterior tympanum are as follows: (1) Bone destruction in the posterosuperior part of the tympanic anulus and in the lateral wall of the facial sinus are the important findings for the diagnosis of invasion of cholesteatoma in the posterior tympanum. (2) Similarly important finding is the bone destruction of the pyramidal eminence. This was found in 6 of 9 cases with cholesteatomas extending into the sinus tympani. (3) The soft tissue density in the posterior tympanum does not necessarily indicate pathological processes. Effusion in the posterior tympanum is imaged as soft tissue density, and can not be differentiated from cholesteatoma or granulation by present HRCT.