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Greater superficial petrosal nerve demonstrated by the novel high-resolution CBCT system. The target structures were identified by adjusting the location and orientation of the axial, sagittal and coronal viewing planes of cone-beam projections on axial axis of a right temporal bone (A, B). BB: Bill's bar; CN: cochlear nerve; EC: electrode contact; G-FN: geniculum of the facial nerve; GSPN: greater superficial petrosal nerve; LSCC: lateral semicircular canal; LS-FN: labyrinth segment of the facial nerve; TS-FN: tympanic segment of the facial nerve. Scale bar ¼ 3 mm.
Source publication
Objective: To test the feasibility of measuring fine temporal bone structures using a newly established cone-beam computed tomography (CBCT) system.
Materials and methods: Six formalin-fixed human cadaver temporal bones were imaged using a high-resolution CBCT system that has 900 frames and copper + aluminum filtration. Fine temporal bone structure...
Context in source publication
Context 1
... landmark to locate the starting point of the tympanic segment of the facial nerve (Fig. 4). The shortest distance between the cochleariform process and the tympanic segment of the facial nerve was 0.5 ± 0.2 mm (mean ± SD) ( Table 1). The greater superficial petrosal nerve that originates from the geniculum of the facial nerve was also identified (Fig. 5). The narrowest site of the meatal foramen measured 0.9 ± 0.3 mm (mean ± SD, Table 1). The semicircular canals were illustrated with high accu- racy, and the supralabyrinthine space was clearly demonstrated (Fig. 6). Among the supralabyrinthine space (air cell tract), posterosuperior, posteromedial, subarcuate, and anterior tracts were ...
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A case of perilymphatic fistula with the luxation of the stapes into vestibule was described, which was caused by a direct damage of the eardrum (the patient cleaned the right ear with a cotton swab and received a strong blow to the arm). The moment of injury was characterized by severe pain, a significant hearing loss, the appearance of tympanopho...
Citations
... When imaging the middle ear, the soft tissue resolution is limited due to the attenuation caused by the dense bony structures of the temporal bone [21]. A previous study by Zou et al. [22] identified and measured fine human cadaver temporal bone structures with a high-resolution CBCT device with constant imaging parameters and found the utility of the system appropriate in middle ear imaging. Using human cadaver temporal bones, too, a study by Kemp et al. [6] compared quality and EDs of high-resolution CBCT and MSCT in middle ear imaging by evaluating anatomical landmarks of the middle and inner ear. ...
... Concerning the lower image quality, they found out a dose reduction of mAs to be more efficient than an equivalent reduction of kVp. In a study by Zou et al. [22], human cadaver temporal bones were imaged with a new CBCT device with optimized imaging parameters and the anatomical landmarks in the images were measured. They found that particular CBCT device to be competent in imaging fine structures of the middle ear. ...
Background
Multi slice computed tomography (MSCT) is the most common used method in middle ear imaging. However, MSCT lacks the ability to distinguish the ossicular chain microstructures in detail resulting in poorer diagnostic outcomes. Novel cone beam computed tomography (CBCT) devices’ image resolution is, on the other hand, better than MSCT resolution. The aim of this study was to optimize imaging parameters of a novel full body CBCT device to obtain optimal contrast to noise ratio (CNR) with low effective dose, and to optimize its clinical usability.
Methods
Imaging of five anonymous excised human cadaver temporal bones, the acquisition of the effective doses and the CNR measurements were performed for images acquired on using Planmed XFI® full body CBCT device (Planmed Oy, Helsinki, Finland) with a voxel size of 75 µm. All images acquired from the specimens using 10 different imaging protocols varying from their tube current exposure time product (mAs) and tube voltage (kVp) were analyzed for eight anatomical landmarks and evaluated by three evaluators.
Results
With the exception of protocol with 90 kVp 100 mAs, all other protocols used are competent to image the finest structures. With a moderate effective dose (86.5 µSv), protocol with 90 kV 450 mAs was chosen the best protocol used in this study. A significant correlation between CNR and clinical image quality of the protocols was observed in linear regression model. Using the optimized imaging parameters, we were able to distinguish even the most delicate middle ear structures in 2D images and produce accurate 3D reconstructions.
Conclusions
In this ex vivo experiment, the new Planmed XFI® full body CBCT device produced excellent 2D resolution and easily created 3D reconstructions in middle ear imaging with moderate effective doses. This device would be suitable for middle ear diagnostics and for e.g., preoperative planning. Furthermore, the results of this study can be used to optimize the effective dose by selecting appropriate exposure parameters depending on the diagnostic task.
... The imaging can be done in supine, sitting or an erect posture. Computed Tomography Dose Index (CTDI) of a CT scan of middle ear is around 170 mGy compared to 15-30 mGy for Cone Beam CT. 9,[11][12][13][14][15][16] Another advantage is that CBCT is very fast, usually taking between 9-18 seconds, and is available in an OPD setting, thus more convenient. Furthermore, it is an open device, so it can be done even in claustrophobic and anxious persons. 2 The aim of this study was to determine any change in management plan of evaluated cases of COM (Mucosal) post CBCT as assessed by the treating ENT Surgeon. ...
: Imaging of temporal bone helps the Otologists in preoperative surgical planning in ear surgery. Cone Beam Computed Tomography (CBCT) has much higher spatial resolution and clarity as compared to conventional X-Ray and much lower radiation exposure as compared to HRCT Temporal Bones.
: To evaluate the change in management plan of Chronic Otitis Media (Mucosal) after CBCT. Also to determine the sensitivity and specificity of the CBCT findings by comparing with intra operative findings in the study participants.
We conducted an observational descriptive study in the ENT Department of an academic Tertiary care hospital from October 2017 to October 2019. We included 95 patients whose management plan before CBCT was compared with the plan after CBCT and the percentage of cases undergoing a change in the management after CBCT was determined. The correlation of CBCT findings and intra operative findings in terms of specificity and sensitivity was also statistically calculated.
: Subsequent to imaging, the management plan was changed in only 4 patients which was statistically non-significant. CBCT showed a 100% sensitivity, specificity, positive predictive value and negative predictive value to detect pneumatisation of the Mastoid, high jugular bulb and low-lying dura. The sensitivity to detect ossicular erosion was 98.9%.
: Thorough clinical examination is the most important factor in decision making in patients with Chronic Otitis Media (Mucosal) and management plan remains unchanged after imaging. Though thorough clinical examination remains the gold standard in making a management plan of patients with Chronic Otitis Media (Mucosal), CBCT with its available details and minimal radiation helped to minimise intraoperative inadvertent injuries which might result due to normal anatomic variations like low lying dura, forward lying sinus, contracted mastoid cavity etc.
... As early as 15 years ago, Peltonen et al. [5] demonstrated the substantial potential of CBCT for imaging the middle ear; however, multi-slice computed tomography (MSCT) is still the standard method. The most recent articles rank CBCT as equal or superior to MSCT in terms of image quality (IQ) and resolution [6][7][8]. However, these studies compared images of cadaver heads and are thus free of reallife motion artifacts. ...
... The meningoencephalocele protrudes through the tegmen tympani and is in contract with the incus and the malleus provides crisp, clear images of the bony structure with radiation doses ranging from 1.6 mSv for adults to 7.1 mSv for new-borns, an amount equivalent to 6-24 months of background radiation [8,12]. CBCT can produce images that are as good or even better [5][6][7]9]. However, the hypernym CBCT includes a variety of hardware, software and setting combinations, our combinations in this article are named as HR CBCT and ULD CBCT. ...
... The IQ of CBCT images could be further enhanced if the patient were supine during scanning (this would reduce motion artefact) and by adjusting the primary focal area on the ear. In optimal circumstances (in vitro), superb resolution of fine structures (stapes, incudostapedial joint, tendon of the tensor tympani and the stapes footplate, to name a few) is possible with CBCT (tube voltage: 88 kV; tube current: 11 mA; voxel size: 0.1 mm; FOV: 60 × 60 mm) [5,7]. We knew from experience that ULD CBCT with our specifications is not likely to produce clinically sufficient images of these above mentioned structures, hence majority of them were not even included in our list of structures. ...
Purpose
This study will evaluate the clinical quality and usability of peripheral image data from the temporal bone area obtained using a sinonasal ultra-low-dose (ULD) cone-beam computed tomography (CBCT) scan and compare them to those obtained using a high-resolution (HR) CBCT.
Methods
The population consisted of 66 anatomical sites (ears of 33 subjects) imaged using two modalities: an HR CBCT (Scanora 3Dx scanner; Soredex, Tuusula, Finland) and a ULD CBCT (Promax 3D Mid scanner; Plandent, Helsinki, Finland). The image quality (IQ) for every anatomical site in each image was rated using a Likert scale from 0 to 5.
Results
The quality of ULD CBCT scans was clinically sufficient in over 95% of the assessed images of the sigmoid sinus, jugular bulb, epitympanum and mastoid antrum as well as external acoustic meatus (all p > 0.05 compared to HR CBCT). The IQ was clinically sufficient in 75–94% of the assessed images of the scutum, mastoid segment of the facial nerve, cochlea and semicircular canals (all p < 0.05 compared to HR CBCT). The overall IQ of the HR CBCT scans was good or excellent.
Conclusion
CBCT imaging and the data at image margins are underutilized. CBCT can produce excellent structural resolu- tion with conventional imaging parameters, even with off-focus images. Using ultra-low doses of radiation, the produced IQ is clinically sufficient. We encourage ear surgeons to check the patients’ imaging history and to consider the use of imaging modalities that involve lower radiation doses especially when conducting repetitive investigations and with children.
... Therefore, preoperative cone beam computed tomography or computed tomography (CT) is the only way to evaluate the continuity of the bone structure of the fossa [13,14]. CT is accepted as the gold standard for clinical evaluation of temporal bone structures [15,16]. ...
Purpose:
Petrotympanic fissure (PF) is important for both dentists and otolaryngologists to know the temporal anatomy well especially for pre-surgical radiological evaluations. Computed tomography (CT) is indispensable method for temporal bone imaging. The purpose of this study was to evaluate PF morphology and position using CT.
Methods:
CT scans of 300 patients (600 PFs) were retrospectively evaluated. PF types were recorded by dividing into 3 groups (Type 1,2 and 3). Length of the mandibular fossa (MF) and PF, vertical diameter (VD) of the PF at the MF level, midpoint and tympanic cavity (TC) level were measured. PF position types were subdivided as low, midline and high.
Results:
Type 1, 2 and 3 was found in 18.7%, 51.5% and 29.8% of the cases, respectively. The mean length of the MF and PF was 18.33 mm and 3.77 mm, respectively. The mean VD of the PF at the MF level, midpoint and TC level was 1.71, 0.98 and 0.97 mm, respectively. The low, midline and high position of PF was observed 14.5%, 54.3% and 31.2% of the cases, respectively.
Conclusion:
Length of the MF and PF in males was significantly higher than females. VD of the PF at the MF level in Type 1 and Type 3 was significantly higher than type 2. In type 1,VD of the PF at the midpoint was significantly higher than type 2 and type 3. VD of the PF at the TC level in Type 1 and Type 3 was significantly higher than type 2.
... In general, CBCT has been explored for applications in endodontic surgical planning, and dentoalveolar trauma evaluation. 29 Recently, CBCT has been used to image bony structures of the anterior and lateral skull base because the radiation dose of CBCT is lower than that of CT. 30,31 Peltonen et al. 32 suggested that CBCT images were at least equivalent to those from multi-detector row CT. Kemp et al. 4 also described high-quality images and low-dose radiation when using CBCT for the middle ear. ...
Objective:
Anatomical information regarding the eustachian tube (ET) is limited; therefore, more detailed analytical data on ET structure is needed when planning surgical treatments involving the temporal bone.
Methods:
We examined the bony structure of the middle ear and ET in 30 Japanese donor cadavers (71-97 years old at the time of death) both macroscopically and with cone-beam computed tomography. Each ET was reconstructed in 3 dimensions, and the structure and correlations of ET element measurements, identified via principal component analysis, were analyzed.
Results:
Delineation between bony and cartilaginous zones appeared unclear, and the space between ET cartilage and the carotid canal was narrow. We observed stenosis of the ET bony canal in 43.3% of the specimens (n = 30). In 50% of the specimens, the position of the ET bony canal was depressed at the pharyngeal orifice of the auditory side of the tube, and the middle region was a roundish structure. The lateral and central regions of the bony canal were related to the ET bony canal structure.
Conclusion:
The close proximity of the ET bony canal to the carotid canal is an important anatomical and morphological finding. Pre-surgical 3D modeling of the middle ear structure, or at a minimum, of the central region of the middle ear canal, may provide useful information for planning procedures that involve the ET.
... For example, the standard MDCT image in Fig. 2b resembles the exemplar clinical image in Fig. 1c of Phillips et al. 31 , while the poor MDCT image in Fig. 2c is noticeably worse. The next-generation CBCT image in Fig. 2a is superior to those currently found in clinical practice, but resembles the state-of-the-art research images in Zou et al. 32 . ...
There is considerable interpersonal variation in the size and shape of the human cochlea, with evident consequences for cochlear implantation. The ability to characterize a specific cochlea, from preoperative computed tomography (CT) images, would allow the clinician to personalize the choice of electrode, surgical approach and postoperative programming. In this study, we present a fast, practicable and freely available method for estimating cochlear size and shape from clinical CT. The approach taken is to fit a template surface to the CT data, using either a statistical shape model or a locally affine deformation (LAD). After fitting, we measure cochlear size, duct length and a novel measure of basal turn non-planarity, which we suggest might correlate with the risk of insertion trauma. Gold-standard measurements from a convenience sample of 18 micro-CT scans are compared with the same quantities estimated from low-resolution, noisy, pseudo-clinical data synthesized from the same micro-CT scans. The best results were obtained using the LAD method, with an expected error of 8–17% of the gold-standard sample range for non-planarity, cochlear size and duct length.
... Studies on temporal bones concluded that CBCT is at least as accurate as MSCT when assessing the visibility of clinically important anatomic structures [1,[8][9][10] . CBCT has also been described as suitable and, in many ways, equivalent to MSCT for postoperative cochlear implant (CI) imaging [5,11,12] and in the assessment of otosclerosis [13] . ...
... Temporal bone studies [1,8,10,14] concluded that CBCT is comparable to MSCT when assessing visibility of clinically important anatomic struc- Postoperative CI imaging studies [5,11,12] showed no significant differences in the overall image quality between CBCT and MSCT as well. In previous cadaver studies temporal bones [1,9,10] , the temporal bones placed within a custom head phantom [14] or hemi-cadaver heads [8] were used, which may have affected the results. ...
Objectives:
Multislice computed tomography (MSCT) is commonly used as a diagnostic tool for patients with a conductive hearing loss. Recent studies indicate that cone-beam computed tomography (CBCT) may be used as a low-radiation dose alternative for temporal bone imaging. This study compares image quality and radiation dose between CBCT and MSCT when assessing anatomical landmarks related to conductive hearing loss.
Materials and methods:
Five human cadaver heads (10 ears) were imaged on the NewTom 5G CBCT and the Discovery CT750 HD MSCT. Visibility of 16 anatomical landmarks of the middle and inner ear was assessed by two observers on a 4-point Likert scale. Furthermore, effective radiation dose was compared, and contrast-to-noise ratio and spatial resolution were measured with a phantom head.
Results:
Image quality of CBCT was assessed as superior to MSCT. Effective radiation dose of the high-resolution CBCT protocol was 30.5% of the clinical MSCT dose. High-resolution CBCT was reported as having a higher spatial resolution and superior contrast-to-noise perception in comparison with MSCT.
Conclusion:
High-resolution CBCT was evaluated as superior to MSCT in the assessment of structures related to conductive hearing loss. Furthermore, CBCT imaging resulted in a considerably lower effective radiation dose.
... MDCT has also a more generalized use in clinical practice and there are large repositories of head scans generated with this technology that may be used for research purposes. Moreover, for several years, it has been considered the gold standard for clinical evaluation of temporal bone structures [7,30]. ...
Purpose
The purpose of the current study is twofold. First, to investigate the variability of the petrotympanic fissure’s (PTF) morphology in anatomized human cadaveric specimens using multi-detector computed tomography (MDCT), and second, to compare the resulting measurements to investigate the possibilities of applying MDCT in the determination of PTF morphology in living humans.
Methods
Specimens (n = 15) containing the temporal bone and TMJ were obtained from embalmed adult female (53.3%) and male (46.7%) cadavers and imaged using a helical 16-row scanner. Afterwards, cryosections were obtained and morphometric parameters were measured. Degree of agreement between both determinations was investigated and morphometric variables were also compared between PTF types.
Results
Three different types of PTF were identified. Type 1 was a wide tunnel-shaped structure. It was found in 20% of the cases. Type 2 was wide in the entrance but gradually narrows to the tympanic cavity. It was found in 46.7% of specimens. Finally, type 3, which was observed in 33.3% of the cases, was wide at the entrance of the mandibular fossa, followed by a middle region with flat-shaped tunnel structure and a narrow exit. The PTF’s vertical diameters at the mandibular fossa, midpoint, and tympanic cavity and the width at the mandibular fossa all were significantly greater in type 1 specimens.
Conclusions
MDCT is suitable for investigating the variable morphology of human PTF and its association with middle ear’s and TMJ pathologies.
... Previous studies on assessing the relevance of 3D-printed models have been limited to survey evaluations from surgeons (15,22), mechanical tests on thickness and hardness (15,23), functional tests (24,25), and studies with few or no anatomical data (11,26,27). However, comprehensive validation studies relying on quantitative measurements of anatomical features are necessary to determine the clinical applicability of these 3D models (28,29). ...
Hypothesis: 3D technologies, including structured light scanning (SLS), micro-computed tomography (micro-CT), and 3D printing, are valuable tools for reconstructing temporal bone (TB) models with high anatomical fidelity and cost-efficiency.
Background: Operations involving TB require intimate knowledge of neuroanatomical structures—a demand that is currently met through dissection of limited cadaveric resources. We aimed to document the volumetric reconstruction of TB models using 3D technologies and quantitatively assess their anatomical fidelity.
Methods: In the primary analysis, 14 anatomical characteristics of right-side TB from 10 dry skulls were measured. Each skull was 3D-scanned using SLS to generate virtual models, which were measured using mesh processing software. Metrics were analyzed using mean absolute differences and one-sample t tests with Bonferroni correction. In the secondary analysis, an individualized right-side TB specimen (TBi) was 3D-scanned using SLS and micro-CT, and 3D-printed on a stereolithography printer. Measurements of each virtual and 3D-printed model were compared to measurements of TBi.
Results: Significant differences between the physical skulls and virtual models were observed for 11 of 14 parameters (p < 0.0036), with the greatest mean difference in the length of petrous ridge (2.85 mm) and smallest difference in the diameter of stylomastoid foramen (0.67 mm). In the secondary analysis, greater mean differences were observed between TBi and virtual models than between TBi and 3D-printed models.
Conclusion: For the first time, our study provides quantitative measurements of TB anatomy to demonstrate that 3D technologies can facilitate individualized and highly accurate reconstructions of TB, which may benefit anatomy education, clinical training, and preoperative planning.
... Cone-beam CT was introduced in mid 90 s and has been used, especially in dental and maxillofacial radiology. Although high-resolution CT is the gold standard in the imaging of the temporal bone, there is an increasing number of papers that report attempts to use CBCT in otorhinolaryngology [8,22] and imaging of the fine structures inside the temporal bone [11], particularly when there is need for preoperative assessment of cochlear implantation, or postoperative follow-up. Cone-beam CT technique is still developing and it seems to be a promising method for the diagnostics of chronic otitis media, or traumatic lesions. ...
Purpose of the study
Körner’s septum (KS) is a developmental remnant formed at the junction of mastoid and temporal squama, representing the persistence of the petrosquamosal suture. During mastoid surgery, it could be taken as a false medial wall of the antrum so that the deeper cells might not be explored. The aim of the study was to assess a Körner’s septum prevalence and to analyze its topography.
Methods
The study was performed on 80 sets of cone-beam computed tomography (CBCT) images of temporal bone (41 male, 39 female, 160 temporal bones). Körner’s septum was identified and its thickness was measured on axial sections at three points: at the level of superior semicircular canal (SCC), at the level of head of malleus (HM) and at the level of tympanic sinus (TS).
Results
KS was encountered at least in one point of measurements in 50 out of 80 sets of CBCT images (62.5%). The average thickness at the level of SCC was 0.87 ± 0.34 mm, at the level of HM was 0.99 ± 0.37 mm and at the level of TS was 0.52 ± 0.17 mm.
Conclusions
Körner’s septum is a common structure in the temporal bone–air cell complex. It is more often encountered in men. In half of the patients, it occurs bilaterally. However, in most of the cases it is incomplete with anterior and superior portions being the most constant.
