Temporal Bone Computed Tomography Research Articles

Synthetic temporal bone CT generation from UTE-MRI using a cycleGAN-based deep learning model: advancing beyond CT-MR imaging fusion.

The aim of this study is to develop a deep-learning model to create synthetic temporal bone computed tomography (CT) images from ultrashort echo-time magnetic resonance imaging (MRI) scans, thereby addressing the intrinsic limitations of MRI in localizing anatomic landmarks in temporal bone CT. This retrospective study included patients who underwent temporal MRI and temporal bone CT within one month between April 2020 and March 2023. These patients were randomly divided into training and validation datasets. A CycleGAN model for generating synthetic temporal bone CT images was developed using temporal bone CT and pointwise encoding-time reduction with radial acquisition (PETRA). To assess the model's performance, the pixel count in mastoid air cells was measured. Two neuroradiologists evaluated the successful generation rates of 11 anatomical landmarks. A total of 102 patients were included in this study (training dataset, n = 54, mean age 58 ± 14, 34 females (63%); validation dataset, n = 48, mean age 61 ± 13, 29 females (60%)). In the pixel count of mastoid air cells, no difference was observed between synthetic and real images (679 ± 342 vs 738 ± 342, p = 0.13). For the six major anatomical sites, the positive generation rates were 97-100%, whereas those of the five major anatomical structures ranged from 24% to 83%. We developed a model to generate synthetic temporal bone CT images using PETRA MRI. This model can provide information regarding the major anatomic sites of the temporal bone using MRI. The proposed algorithm addresses the primary limitations of MRI in localizing anatomic sites within the temporal bone. CT is preferred for imaging the temporal bone, but has limitations in differentiating pathology there. The model achieved a high success rate in generating synthetic images of six anatomic sites. This can overcome the limitations of MRI in visualizing key anatomic sites in the temporal skull.

Congenital Unilateral Hearing Loss from Cochlear Nerve Canal Stenosis

A 2-month-old baby girl presented with a failed neonatal otoacoustic emission (OAE) hearing screening in the left ear. Combined Auditory Brainstem Response/Auditory Steady-State Response (ABR/ASSR) testing confirmed the presence of a unilateral left moderate to severe hearing loss. No Joint Committee on Infant Hearing (JCIH) risk factors for early childhood hearing loss1 were identified. She subsequently underwent computed tomography (CT) of the temporal bones to determine the presence of any inner ear malformation. No abnormalities of the internal auditory canal, cochlea, semicircular canals and ossicles were noted by the radiologist, and the study was officially reported as a “normal temporal bone CT scan.” Independent review of the CT imaging revealed the presence of a visually apparent disparity in the width of the cochlear nerve canals. (Figure 1) Measurement of the cochlear nerve canal width in the axial plane parallel to the infraorbitomeatal line2 using the length measurement tool in the DICOM imaging software (RadiAnt DICOM Viewer, Version 2024.1, Medixant) indicated a cochlear nerve canal width of 2.18 mm on the right and 1.02 mm on the left. (Figure 2) Applying the suggested cutoff point of 1.2 mm as described by Lin et al.,2 we identified the presence of left cochlear nerve canal stenosis as the etiology of the congenital unilateral hearing loss. The cochlear nerve canal, which has also been referred to as the bony canal for the cochlear nerve (BCNC), cochlear aperture, and cochlear fosette, is the bony transition point between the internal auditory canal and the cochlear modiolus. A relationship between a hypoplastic cochlear nerve canal and congenital sensorineural hearing loss was first suggested by Fatterpekar et al. in 2000.3 Subsequent studies confirmed the association between cochlear nerve canal stenosis and sensorineural hearing loss that ranges from near-normal to profound, with a statistically significant relationship between the degree of hearing loss and the degree of stenosis.4 Various cutoff points to define stenosis of the cochlear nerve canal have been identified in the medical literature. These cutoff points range from 1.2 mm to 1.7 mm when the canal width is measured in the axial plane.2 This particular case demonstrated clear-cut evidence of cochlear nerve canal stenosis, as it satisfied the smallest cutoff criteria (< 1.2 mm) seen in the medical literature. The identification of cochlear nerve canal stenosis as the cause of congenital sensorineural hearing loss is important not only from a diagnostic point, but also from a prognostic perspective. Cochlear nerve deficiency has been noted to be highly prevalent among pediatric patients with cochlear nerve canal stenosis,5 and this has significant negative implications in relation to rehabilitation with external hearing devices and cochlear implants.

Fungal carotiditis with aneurysm - a rare complication of mucormycosis: presentation and management

During the COVID-19 pandemic, cases of mucormycosis (ROCM) had increased drastically, especially in the second wave. Most of these cases involved the paranasal sinuses, orbit and occasionally brain. This case report presents a rare case of mucormycosis complicated with a mycotic aneurysm of the petrous part of the internal carotid artery (ICA). A 43-year-old man presented with left-sided facial weakness for which high resolution computed tomography scan of the Temporal bones was done. A scrutiny of the computed tomography temporal bone showed evidence of osteomyelitis extending to the petrous apex around the foramen Lacerum. Computed tomography and magnetic resonance imaging of the paranasal sinus done later confirmed the diagnosis of mucormycosis. The patient underwent endoscopic surgical debridement of the nose and sinuses, with post-operative amphotericin B. After 3 weeks, the patient presented with bouts of profuse nasal bleed. Computed tomography angiogram showed an aneurysm in the petrous segment of the ICA suggestive of mycotic carotiditis complicated from mucormycosis spread along the skull base. It was successfully managed neurosurgically by a bypass shunting procedure. Mucormycosis is a disease that typically has an aggressive and startling fatality rate. ICA aneurysm is an uncommon occurrence in mucormycosis. Subjects with ROCM should be examined for brain and vascular involvement. Computed tomography angiogram should be performed as soon as possible if the skull base is involved in the ICA area. Morbidity and mortality can often be reduced by early diagnosis and interventions by a multidisciplinary team.

High Prevalence of Cochlear Nerve Deficiency in Pediatric Patients With Cochlear Aperture Stenosis.

Cochlear nerve deficiency (CND) is a common radiologic finding among unilateral sensorineural hearing loss (USNHL) patients. It is generally detected with magnetic resonance imaging (MRI), which is associated with higher cost, less availability, and possible need for sedation. Therefore, identifying computed tomography (CT) findings, such as cochlear aperture stenosis (CAS), that can reliably predict CND is valuable. Our study aimed to determine the prevalence of CND in pediatric patients with CT-diagnosed CAS. Retrospective study. Tertiary care center. We included pediatric patients diagnosed with CAS on temporal bone CT and with available temporal bone MRI. For each patient, an otolaryngologist and a pediatric neuroradiologist measured the cochlear aperture width on CT to confirm CAS (cochlear aperture < 1.4 mm) and assessed the status of the cochlear nerve on MRI. Fifty-five patients, representing 65 ears, had CAS on CT measurement. Median cochlear aperture width in CAS ears was 0.70 mm (interquartilerange [IQR]: 0.40-1.05 mm) versus 2.00 mm in non-CAS ears (IQR: 1.80-2.30 mm, P < .001). CND was found in 98.5% (n = 64/65) of CAS ears, while a normal cochlear nerve was found in 1.5% (n = 1/65) of CAS ears. CND is highly prevalent among pediatric patients with CAS. This suggests that MRI may not be needed to assess for CND in USNHL patients with CAS, as initial CT may provide sufficient information to determine cochlear implant candidacy. We recommend thoughtful shared decision-making with parents of USNHL patients when determining whether to pursue MRI in the setting of a CAS diagnosis.

Topographic Radioanatomical Analysis of the Singular Canal: Computed Tomography Study

Purpose: The singular canal (SC) is where the singular nerve, a branch of the inferior vestibular nerve, which carries afferent information from the posterior semicircular canal (PSCC), passes and is important in the surgical approach of the presigmoid retrolabyrinthine. This study was carried out to evaluate the visibility of the SC on standard computed tomography (CT) images, its distance to the surrounding structures, and to investigate the variations of its anatomy and its relationship with the meatus acusticus internus. Materials and Methods: The study was carried out retrospectively using images of 194 temporal bones on temporal bone CT scans of 44 men and 53 women aged 18–65. In the study, various measurements were made, especially the presence of the SC, its length, its angle with the internal acoustic canal (IAC), and the distance between the internal acoustic pore (IAP) and the singular foramen. In addition, the presence of the high jugular bulb and PSCC dehiscence images were investigated. Results: The SC was detected in 85.1% of the analyzed images. The mean canal length was 3.93 ± 1.22 mm, the angle between the SC and the IAC was 22.68° ±3.60°, and the distance between the SC and the IAP was 7.70 ± 0.83 mm. While no difference was found between the sides, it was determined that the length and diameter of the SC did not differ according to gender. Conclusion: Detailed morphometric analysis of the SC and a thorough understanding of its relationship with the IAC, vestibulum, and PSCC will help to accurately define the posterior and lateral borders of the dissection for this region.

Topographic Radioanatomical Analysis of the Singular Canal: Computed Tomography Study

Purpose: The singular canal (SC) is where the singular nerve, a branch of the inferior vestibular nerve, which carries afferent information from the posterior semicircular canal (PSCC), passes and is important in the surgical approach of the presigmoid retrolabyrinthine. This study was carried out to evaluate the visibility of the SC on standard computed tomography (CT) images, its distance to the surrounding structures, and to investigate the variations of its anatomy and its relationship with the meatus acusticus internus. Materials and Methods: The study was carried out retrospectively using images of 194 temporal bones on temporal bone CT scans of 44 men and 53 women aged 18–65. In the study, various measurements were made, especially the presence of the SC, its length, its angle with the internal acoustic canal (IAC), and the distance between the internal acoustic pore (IAP) and the singular foramen. In addition, the presence of the high jugular bulb and PSCC dehiscence images were investigated. Results: The SC was detected in 85.1% of the analyzed images. The mean canal length was 3.93 ± 1.22 mm, the angle between the SC and the IAC was 22.68° ±3.60°, and the distance between the SC and the IAP was 7.70 ± 0.83 mm. While no difference was found between the sides, it was determined that the length and diameter of the SC did not differ according to gender. Conclusion: Detailed morphometric analysis of the SC and a thorough understanding of its relationship with the IAC, vestibulum, and PSCC will help to accurately define the posterior and lateral borders of the dissection for this region.

Deep learning reconstruction improves the image quality of low-dose temporal bone CT with otitis media and mastoiditis patients

ObjectiveTo evaluate the image quality of low-dose temporal bone computed tomography (CT) in otitis media and mastoiditis patients by using deep learning reconstruction (DLR). Materials and methodsA total of ninety-seven temporal bones from 53 consecutive adult patients who had suspected otitis media and mastoiditis and underwent temporal bone CT were prospectively enrolled. All patients underwent high resolution CT protocol (group A) and an additional low-dose protocol (group B). In group A, high resolution data were reconstructed by filter back projection (FBP). In group B, low-dose data were reconstructed by DLR mild (B1), DLR standard (B2) and DLR strong (B3). The objective image quality was analyzed by measuring the CT value and image noise on the transverse image and calculating the signal-to-noise ratio (SNR) on incudomallear joint, retroauricular muscle, vestibule and subcutaneous fat. Subjective image quality was analyzed by using a five-point scale to evaluate nine anatomical structures of middle and inner ear. The number of temporal bone lesions which involved in five structures of middle ear were assessed in group A, B1, B2 and B3 images. ResultsThere were no significant differences in the CT values of the four reconstruction methods at four structures (all p > 0.05). The DLR group B1, B2 and B3 had significantly less image noise and a significantly higher SNR than group A at four structures (all p < 0.001). The group B1 had comparable subjective image quality as group A in nine structures (all p > 0.05), however, the group B3 had lower subjective image quality than group A in modiolus, spiral osseous lamina and stapes (all p < 0.001), the group B2 had lower subjective image quality than group A in modiolus and spiral osseous lamina (both p < 0.05). The number of temporal bone lesions which involved in five structures for group A, B1 and B2 images were no significant difference (all p > 0.05), however, the number of temporal bone lesions which involved in mastoid for group B3 images were significantly more than group A (p < 0.05). The radiation dose of high resolution CT protocol and low-dose protocol were 0.55 mSv and 0.11 mSv, respectively. ConclusionCompared with high resolution CT protocol, in the low-dose protocol of temporal bone CT, DLR mild and standard could improve the objective image quality, maintain good subjective image quality and satisfy clinical diagnosis of otitis media and mastoiditis patients.

Quantification of Mastoid Air Cells and Opacification of the Middle Ear in Primary Ciliary Dyskinesia.

To evaluate pneumatization and opacification of the temporal bone on computed tomography (CT) images in patients with primary ciliary dyskinesia (PCD). Retrospective case-control study. Tertiary referral center. Fifteen patients with PCD (30 ears) and 45 age-matched individuals without PCD (90 ears) as controls. Diagnostic only. Quantification of mastoid air cells in the PCD and control groups and comparison between them. Degree of middle ear opacification on CT images of the temporal bone in the PCD group. The volume of the mastoid air cells was 30% smaller in the PCD group than in the control group ( p < 0.05). The suppression ratio, which is defined to indicate how much the average volume of mastoid air cells in the PCD group is suppressed relative to the control group, was 64% lower in the PCD group ( p < 0.05). Opacification was noted in 47% of the mastoid air cells and 63% of the tympanic cavity on CT images of the temporal bone in the PCD group, which were significantly higher frequencies than in the control group (1.1% and 1.1%, respectively). Compared with individuals without PCD, those with PCD showed a significantly smaller volume of mastoid air cells and a significantly higher frequency of opacification of mastoid air cells and tympanic cavity on temporal bone CT. Otitis media raises suspicion for PCD, and the otological manifestations of PCD reported here could help to narrow the differential diagnosis and facilitate early treatment.

Post-operative evaluation of computed tomography imaging following cochlear implantation

PurposeThis study utilized an automated segmentation algorithm to assess the cochlear implant electrode array within the cochlea and investigate its impact on audiologic outcomes as measured by post-operative speech perception scores. Furthermore, manual evaluations of electrode placement were compared to automatic segmentation methods to determine their accuracy in predicting post-operative audiologic outcomes. Materials and methodsThis retrospective chart review was conducted at a tertiary care referral center involving adult post-lingually deafened cochlear implant recipients implanted from 2015 to 2019. Patients with appropriate postoperative imaging and speech testing were included. Patients were excluded if non-English speaking, had a cognitive deficit, or a labyrinthine malformation. Automated and manual methods were used to analyze computed tomography (CT) scans and correlate the findings with post-operative speech perception scores and detection of electrode translocation. ResultsAmong the 47 patients who met inclusion criteria, 15 had electrode translocations confirmed by automatic segmentation methods. Controlling for CI usage and pre-operative AzBio scores, patients with translocation exhibited significantly lower consonant-nucleus consonant (CNC) and AzBio scores at 6-months post-implantation compared to patients with ST insertions. Moreover, the number of translocated electrode contacts was significantly associated with post-operative CNC scores. Manual evaluations of electrode location were predictive but less sensitive to electrode translocations when compared with automated 3D segmentation. ConclusionsPlacement of CI electrode contacts within ST without translocation into SV, leads to improved audiologic outcomes. Manual assessment of electrode placement via temporal bone CT, without 3D reconstruction, provides a less sensitive method to determine electrode placement than automated methods. Level of evidenceLevel 4. Lay summaryThis study investigated the impact of electrode placement on speech outcomes for cochlear implant recipients. Using advanced imaging techniques, the researchers compared automated and manual methods for evaluating electrode position and examined the relationship between electrode translocation and audiologic outcomes. The findings revealed that proper placement within the cochlea without translocation into inappropriate compartments inside the cochlea improves speech understanding. Manual evaluations were somewhat accurate but less sensitive in detecting translocations compared to automated methods, which offer more precise predictions of patient outcomes. These results contribute to our understanding of factors influencing cochlear implant success and highlight the importance of optimizing electrode placement for improved speech outcomes.

Comparison of tympanometric volume measurement with temporal bone CT findings in the assessment of mastoid bone pneumatization in chronic otitis media patients.

Since mastoid bone aeration is a pressure buffer for the middle ear, it can be accepted as a prognostic factor for tympanoplasty. Temporal bone computed tomography (TBCT) is a primary method for estimating mastoid aeration. However, due to the risk of radiation and its high cost, there is a need for a more straightforward, faster, and more reliable method in non-complicated chronic otitis media cases (COM). Tympanometric volume measurement might be used for this purpose. This study investigated tympanometric volume measurement's reliability in showing mastoid bone aeration by comparing tympanometric volume measurement with TBCT aeration grading. Preoperative tympanometric volume measurements were performed in patients who underwent audiological examination and temporal computerized tomography (CT) with the diagnosis of COM and sequela of COM without discharge for the last three months and were indicated for surgery. CT was classified into six grades: grade 0: there is no aeration, sclerotic mastoid; grade 1: pneumatization only in the mastoid antrum; grade 2: <25% pneumatization; grade 3: 25-50% pneumatization; grade 4: >50 pneumatization, grade 5: full pneumatization. Averages of tympanometric volume values were determined according to CT degrees. 48 left and 52 right ears (n: 100) of 81 patients, 24 females and 57 males, were included in the study. The mean age was 37.69±13.38. Mastoid pneumatization grades of patients were 32 grade 0, 23 grade 1, 16 grade 2, 14 grade 3, 11 grade 4, and 4 grade 5, respectively. Each grade's mean tympanometric volume (mL) was grade 0: 1.1594, grade 1: 1.6991, grade 2: 2.2250, grade 3: 3.0471, grade 4: 4.0327, and grade 5: 2.9775. There is a statistically significant relationship between tympanometrically measured ear volume and mastoid degrees of pneumatization on temporal bone tomography. As the degree of mastoid aeration increases, the tympanometric volume also increases. According to the results of this study, tympanometric air volume can be used reliably in the preoperative evaluation of mastoid bone aeration in cases of simple COM without ear drainage.

Surgical Outcomes of Sigmoid Sinus Resurfacing for Pulsatile Tinnitus: The Predictive Value of the Water Occlusion Test and Imaging Studies.

Sigmoid sinus resurfacing (SS-R) is one of the most effective surgical treatments for patients with pulsatile tinnitus (PT) originating from anatomical variants of the vascular walls in the temporal bone. This study aimed to provide updated information on the clinical outcomes of SS-R and evaluate the efficacy of the water occlusion test (WOT) as an additional diagnostic modality. We retrospectively reviewed medical records including tinnitus questionnaires, temporal bone computed tomography (TBCT) scans, audiologic tests, and preoperative WOT. from patients who underwent SS-R. In total, 26 patients were included in the study. The mean age was 44 years, and the mean symptom duration was 3 months. Fourteen patients (53.8%) were completely cured, seven (26.9%) significantly improved, and five (19.2%) remained stable. The mean visual analog scale loudness score decreased from 5.26 to 1.34 (P<0.001) and the mean Tinnitus Handicap Inventory score also improved from 50.23 to 5.5 (P<0.001) after SS-R surgery. In 10 patients with discrepancies between the preoperative TBCT and intraoperative findings, WOT showed a significant additive effect in predicting surgical outcomes. No patients experienced severe intraoperative or postoperative complications during the entire follow-up period. SS-R provides significant symptom improvement in patients with sigmoid sinus dehiscence who had a positive WOT without other sigmoid sinus variants. A combined diagnostic approach with TBCT, WOT, and intraoperative findings is crucial for achieving better surgical outcomes in patients with PT caused by sigmoid sinus variants.

The Compatibility of Preoperative Temporal Bone CT Scan Interpretation and Intraoperative Findings in Chronic Suppurative Otitis Media at Dr. Zainoel Abidin Hospital Banda Aceh

Introduction: Chronic suppurative otitis media (CSOM) is middle ear and mastoid infection that causes hearing loss globally. Computed Tomography (CT)-Scan of the temporal bone is useful for assessing the pathogenesis of the disease and estimating the prognosis. In addition, evaluation of CT-Scan in patients with CSOM is useful for selecting the appropriate surgical procedure to minimize post-surgical complications. This study aims to assess the suitability of temporal CT-Scan interpretation to intraoperatif findings in CSOM patients. Methods: This is an observational study with cross-sectional design conducted at the dr. Zainoel Abidin General Hospital, Banda Aceh. The components of suitability evaluation include cholesteatoma, scutum erosion, ossicles, tegmen tympani, facial canal, posterior wall and sigmoid sinus wall. The interpretation suitability of temporal CT-Scan and intraoperatif findings was performed using the Kappa test. Results: A total of 18 CSOM patients were involved in this study with a mean age of 32.44 years and dominated by the safe type with a percentage of 55.6%. Interpretation of ossicular erosion based on temporal CT scan has very strong suitability with the intraoperatif findings with k=0.88 followed by posterior wall erosion (k=0.684), scutum erosion (k=0.679), tympanic tegmen erosion (k=0.455) and facial canal erosion (k=0.341). The findings of cholesteatoma and erosion of the sigmoid sinus wall had a very low suitability (k&lt;0.001). Conclusion: Temporal CT scan in CSOM patients has relatively good suitability with intraoperatif findings in evaluating erosion of the ossicles, posterior wall, and scutum. Another examination modality is necessary to assess and improve the accuracy of disease pathogenesis.

Structure-constrained deep feature fusion for chronic otitis media and cholesteatoma identification.

Chronic suppurative otitis media (CSOM) and middle ear cholesteatoma (MEC) were two most common chronic middle ear disease(MED) clinically. Accurate differential diagnosis between these two diseases is of high clinical importance given the difference in etiologies, lesion manifestations and treatments. The high-resolution computed tomography (CT) scanning of the temporal bone presents a better view of auditory structures, which is currently regarded as the first-line diagnostic imaging modality in the case of MED. In this paper, we first used a region-of-interest (ROI) network to find the area of the middle ear in the entire temporal bone CT image and segment it to a size of 100*100 pixels. Then, we used a structure-constrained deep feature fusion algorithm to convert different characteristic features of the middle ear in three groups as suppurative otitis media (CSOM), middle ear cholesteatoma (MEC) and normal patches. To fuse structure information, we introduced a graph isomorphism network that implements a feature vector from neighbourhoods and the coordinate distance between vertices. Finally, we construct a classifier named the "otitis media, cholesteatoma and normal identification classifier" (OMCNIC). The experimental results achieved by the graph isomorphism network revealed a 96.36% accuracy in all CSOM and MEC classifications. The experimental results indicate that our structure-constrained deep feature fusion algorithm can quickly and effectively classify CSOM and MEC. It will help otologist in the selection of the most appropriate treatment, and the complications can also be reduced.

Feasibility of size-specific organ-dose estimates based on water equivalent diameter for common head CT examinations: a Monte Carlo study

Computed tomography dose index (CTDI) is an unreliable dose estimate outside of the standard CTDI phantom diameters (16 and 32 cm). Size-specific dose estimate (SSDE) for head computed tomography (CT) examination was studied in the American Association of Physicists in Medicine Report 293 to provide SSDE coefficient factors based on water equivalent diameter as size metrics. However, it is limited to one protocol and for a fully irradiated organ. This study aimed to evaluate the dependency of normalized organ dose (ND) on water equivalent diameter as a size metric in three common protocols: routine head, paranasal sinus, and temporal bone. CTDIw measurements were performed for outlined protocols in the Siemens Emotion 16-slice-configuration scanner. Geant4 Application for Tomographic Emission Monte Carlo simulation platform, coupled with ten GSF patient models, was used to estimate organ doses. CT scanner system was modeled. Helical CT scans were simulated using constructor scan parameters and calculated scan lengths of each patient model. Organ doses provided by simulations were normalized to CTDIvol. The water equivalent diameters (D w) of patient models were obtained via relationships between D w and both effective diameter for a sample of patients’ data.NDs received by fully, partially, and non-directly irradiated organs were then reported as a function of D w. For fully irradiated organs, brain (R 2 > 0.92), eyes (R 2 > 0.88), and eye lens (R 2 > 0.89) correlate well with D w. For the rest of the results, a poor correlation was observed. For partially irradiated organs, the exception was scalp (R 2 = 0.93) in temporal bone CT. For non-directly irradiated organs, the exception was thyroid (R 2 > 0.90) and lungs (R 2 > 0.91) in routine head CT. ND correlates well in routine head CT than other protocols. For the most part, no relationship seems to exist between R 2 and scan percentage coverage. The results have revealed additional factors that may influence the ND and D w relationship, which explains the need for more studies in the future to investigate the effect of scan conditions and organ anatomy variation.

Deep learning-based approach for the automatic segmentation of adult and pediatric temporal bone computed tomography images.

Automatic segmentation of temporal bone computed tomography (CT) images is fundamental to image-guided otologic surgery and the intelligent analysis of CT images in the field of otology. This study was conducted to test a convolutional neural network (CNN) model that can automatically segment almost all temporal bone anatomy structures in adult and pediatric CT images. A dataset comprising 80 annotated CT volumes was collected, of which 40 samples were obtained from adults and 40 from children. A further 60 annotated CT volumes (30 from adults and 30 from children) were used to train the model. The remaining 20 annotated CT volumes were employed to determine the model's generalizability for automatic segmentation. Finally, the Dice coefficient (DC) and average symmetric surface distance (ASSD) were utilized as metrics to evaluate the performance of the CNN model. Two independent-sample t-tests were used to compare the test set results of adults and children. In the adult test set, the mean DC values of all the structures ranged from 0.714 to 0.912, and the ASSD values were less than 0.24 mm for 11 structures. In the pediatric test set, the mean DC values of all the structures ranged from 0.658 to 0.915, and the ASSD values were less than 0.18 mm for 11 structures. There was no statistically significant difference between the adult and child test sets in most temporal bone structures. Our CNN model shows excellent automatic segmentation performance and good generalizability for both adult and pediatric temporal bone CT images, which can help to advance otologist education, intelligent imaging diagnosis, surgery simulation, application of augmented reality, and preoperative planning for image-guided otology surgery.

Uneventful Cochlear Implantation through Round Window Approach in a Child with Persistent Stapedial Artery: A Case Report

Persistent stapedial artery (PSA) is a rare congenital vascular anomaly, with both clinical and surgical implications. When encountered during middle ear surgery, it represents a challenge to the otologic surgeon, since damage to this artery could lead to massive intraoperative bleeding and poor surgical exposure. Here we report the case of a 3-year-old boy with prelingual and profound bilateral sensorineural hearing loss who was referred to our Otolaryngology-Head and Neck Surgery Department for cochlear implant evaluation. Pre-operative computed tomography (CT) examination of the temporal bone confirmed the diagnosis of PSA. Further evaluation showed no contraindication for surgery and the patient underwent cochlear implantation using the classic transmastoid, facial recess approach. During surgery the vessel was coursing far enough from the round window niche, making it possible to achieve safe and complete electrode insertion into the scala tympani of the cochlear basal turn. This case demonstrates that cochlear implantation is safe and feasible in patients with PSA. Thorough analysis of the preoperative temporal bone CT scan might help with surgical planning by identifying this anomaly prior to surgery.

Absent Stapedial Tendon: Imaging Features of an Underrecognized Entity : Clinical Neuroradiology.

Congenital absence of the stapedial tendon is arare entity with characteristic imaging findings, which can go unrecognized due the scarcity of the diagnosis and limited previous description in the imaging literature. We aim to characterize the imaging features of this entity. Aseries of 9cases with surgical confirmation of stapedial tendon absence were retrospectively reviewed and the most common abnormalities on high resolution computed tomography (CT) of the temporal bone described. Congenital fixation of the stapes footplate was present in nearly all cases of stapedial tendon absence (n = 8, 89%), aclinically important association because the stapes footplate abnormality was not detectable on preoperative CT. Absence or hypoplasia of the pyramidal eminence and aperture was identified in almost all cases (n = 8, 89%), which may be the sole imaging finding to suggest stapedial tendon absence and associated stapes footplate fixation prior to surgery. The most reliable indicator of stapedial muscle absence on temporal bone CT is the absence or hypoplasia of the pyramidal eminence and aperture. Importantly, most patients had congenital stapes footplate fixation confirmed intraoperatively with anormal stapes footplate on CT, meaning the pyramidal eminence/aperture abnormality was the only preoperative imaging finding that could have suggested the footplate fixation.

Association of Mastoid Pneumatization with Deviated Nasal Septum: A Clinicoradiological Study

Background: Deviated nasal septum (DNS) has been reported to jeopardizing the nasal aerodynamics. This in turn may affect the pressure dynamics in the nasopharynx and eventually affect the development and pneumatization of mastoid air cells. Few studies done previously have shown a positive correlation between nasal pathologies and mastoid pneumatization. Objectives: This study was undertaken to see for the possible association of mastoid cell pneumatization, with DNS. Materials and Methods: Limited high-resolution computed tomography temporal bone and computed tomography nose and paranasal sinuses were used to calculate the mastoid air cell volume and angle of septal deviation. The degree of septal deviation was graded into mild, moderate, and severe. The mastoid air cell system volume was calculated on the side of the convexity of the septal deviation and the other side. Results: It was found that there is a statistically significant difference in the mastoid volume on the affected side of the DNS vis a vis the unaffected side. Further, the degree of reduction of the volume was not a linear function of the degree of septal deviation. Conclusions: Septal deviation significantly reduces the mastoid air cell volume on the affected side Thus, early correction of pathological DNS in adults, irrespective of the etiology, is important, so as to avoid the chances of developing chronic ear pathologies in later life.

Correlative Study of High-Resolution Computed Tomography Temporal Bone with Intraoperative Findings in Tympanomastoid Surgery

Abstract Introduction: The global incidence of chronic otitis media (COM) is approximately 4.76 per thousand, with 31 million cases causing various complications. Most of these patients require one of the various forms of mastoid surgeries. High-resolution computed tomography (HRCT) has greatly improved the ability to assess both bony architecture and soft-tissue status. Aim: The aim is to assess the correlation of HRCT temporal bone with intraoperative findings in tympanomastoid surgery and to evaluate the sensitivity, specificity, positive predictive value, and negative predictive value of HRCT temporal bone. Materials and Methods: This prospective study was conducted in the Department of Otorhinolaryngology, SDM College of Medical Sciences and Hospital, Dharwad from November 2012–April 2014. Fifty patients of COM were taken up for study who underwent preoperative HRCT temporal bone followed by appropriate tympanomastoid surgery. Results: HRCT temporal bone showed increased sensitivity and specificity in detecting ossicular chain erosion and soft tissue abnormality within the middle ear and mastoid air cells. Facial nerve canal erosion was correctly detected in 62.50%, and overall agreement between surgical findings and the scan was high (90%). It also showed a very high specificity of 95.24%. For semicircular canal erosion and dural plate erosion, sensitivity was 50% each, specificity was 100% and had a very good correlation with surgical findings. Two cases of erosion of the posterior bony wall of the external auditory canal were correctly detected by the HRCT scan. Conclusion: HRCT temporal bone was found to have a high overall correlation with surgical findings and can be a useful method for early diagnosis of complications of COM and preoperative assessment.

Comparative analysis of preoperative high-resolution computed tomography temporal bone and intraoperative surgical findings in cases of cholesteatoma

Comparative analysis of preoperative high-resolution computed tomography temporal bone and intraoperative surgical findings in cases of cholesteatoma