Registration of preoperative temporal bone CT-scan to otoendoscopic video for augmented-reality based on convolutional neural networks.

PURPOSE: Patient-to-image registration is a preliminary step required in surgical navigation based on preoperative images. Human intervention and fiducial markers hamper this task as they are time-consuming and introduce potential errors. We aimed to develop a fully automatic 2D registration system for augmented reality in ear surgery. METHODS: CT-scans and corresponding oto-endoscopic videos were collected from 41 patients (58 ears) undergoing ear examination (vestibular schwannoma before surgery, profound hearing loss requiring cochlear implant, suspicion of perilymphatic fistula, contralateral ears in cases of unilateral chronic otitis media). Two to four images were selected from each case. For the training phase, data from patients (75% of the dataset) and 11 cadaveric specimens were used. Tympanic membranes and malleus handles were contoured on both video images and CT-scans by expert surgeons. The algorithm used a U-Net network for detecting the contours of the tympanic membrane and the malleus on both preoperative CT-scans and endoscopic video frames. Then, contours were processed and registered through an iterative closest point algorithm. Validation was performed on 4 cases and testing on 6 cases. Registration error was measured by overlaying both images and measuring the average and Hausdorff distances. RESULTS: The proposed registration method yielded a precision compatible with ear surgery with a 2D mean overlay error of 0.65 ± 0.60 mm for the incus and 0.48 ± 0.32 mm for the round window. The average Hausdorff distance for these 2 targets was 0.98 ± 0.60 mm and 0.78 ± 0.34 mm respectively. An outlier case with higher errors (2.3 mm and 1.5 mm average Hausdorff distance for incus and round window respectively) was observed in relation to a high discrepancy between the projection angle of the reconstructed CT-scan and the video image. The maximum duration for the overall process was 18 s. CONCLUSIONS: A fully automatic 2D registration method based on a convolutional neural network and applied to ear surgery was developed. The method did not rely on any external fiducial markers nor human intervention for landmark recognition. The method was fast and its precision was compatible with ear surgery.

Imaging of Pathologies of the Temporal Bone and Middle Ear: Inflammatory Diseases, Their Mimics and Potential Complications-Pictorial Review.

Imaging of the temporal bone and middle ear is challenging for radiologists due to the abundance of distinct anatomical structures and the plethora of possible pathologies. The basis for a precise diagnosis is knowledge of the underlying anatomy as well as the clinical presentation and the individual patient's otological status. In this article, we aimed to summarize the most common inflammatory lesions of the temporal bone and middle ear, describe their specific imaging characteristics, and highlight their differential diagnoses. First, we introduce anatomical and imaging fundamentals. Additionally, a point-to-point comparison of the radiological and histological features of the wide spectrum of inflammatory diseases of the temporal bone and middle ear in context with a review of the current literature and current trends is given.

Quiste epidermoide en conducto auditivo externo: reporte de caso / Epidermoid cysts of the external auditory canal: case report

Resumen El quiste epidérmico es una lesión benigna y común de la piel. Se desarrolla por un bloqueo de la unidad pilosebácea, con la consecuente proliferación de células epiteliales y secuestro de queratina. El 7% se desarrollan en cabeza y cuello, sin embargo, son infrecuentes en canal auditivo externo. Su patrón de crecimiento es lento y progresivo durante años, siendo asintomáticos. Al aumentar de tamaño causan sintomatología variable, acorde a su localización; en el canal auditivo tienen un comportamiento obstructivo que genera síntomas como otalgia e hipoacusia. Se presenta caso de una paciente de 69 años, con acúfeno e hipoacusia progresiva derecha. Durante la otoscopia se observó una neoformación obstructiva del 100% de la luz del conducto. Se realizaron estudios de imagen que reportaron tumoración de características quísticas de conducto auditivo derecho, bien circunscrita, sin erosión ósea. Para el diagnóstico definitivo, se realizó resección quirúrgica y biopsia reportando quiste epidérmico. Durante el seguimiento posoperatorio sin hallazgos de recidiva.

Abstract The epidermal cyst is a common and benign lesion of the skin. It develops due to a blockage of the pilosebaceous unit, with the consequent proliferation of epithelial cells and keratin sequestration. Seven percent develop in the head and neck; however, they are infrequent in the external auditory canal. Its growth pattern is slow and progressive over the years, being asymptomatic. As they increase in size, they cause variable symptoms, according to their location. In the ear canal they have an obstructive behavior that generates symptoms such as earache and hearing loss. A case of a 69-year-old female with tinnitus and progressive right hearing loss is presented. At otoscopy, a 100% obstructive neoformation of the canal lumen was observed. Imaging studies showed a well circumscribed, cystic tumor of the right ear canal, without bone erosion. For the definitive diagnosis, a resection and biopsy were performed, reporting an epidermal cyst. During follow up there was no recurrence of tumor.

Fibroepithelial Polyp of the External Auditory Canal in a 2-Year-Old Child.

Here, we report a unique case in which a fibroepithelial polyp was found in the cartilaginous part of the external auditory canal of a 2-year-old child. The polyp was successfully treated by excision using an endaural approach and healed without complications. This is the very first report of a fibroepithelial polyp in the external auditory canal in the pediatric population. Although fibroepithelial polyp is an extremely rare diagnosis, it should be considered in the differential diagnosis of a child's external auditory canal polyp.

External Ear Diseases: A Comprehensive Review of the Pathologies With Neuroradiological Considerations.

The peripheral auditory system is subdivided into 3 compartments: the external, middle, and inner ear. Historically, the middle and inner ear have garnered more attention in the imaging literature, due to their intricate anatomy and complexity of pathologies. The external ear, however, has attained less recognition given its relatively straightforward anatomy and convenience of direct visual examination. The continued advancement in computed tomography and magnetic resonance imaging has expanded the role of radiology in the evaluation of the external ear lesions. The purpose of this article is to offer a comprehensive review of external ear pathologies, including congenital, inflammatory, infectious, traumatic, neoplastic, and rare disease entities and their imaging findings.

Exteriorization of Petrous Bone Cholesteatoma by Endonasal Endoscopic Approach: A Case Report.

A 61-year-old woman presented with diplopia and headache. The patient had a longstanding history of petrous bone cholesteatoma (PBC) on the left side and had undergone multiple surgeries to address it. Computed tomography (CT) revealed a radiolucent lesion with bony destruction in the left petrous apex. Magnetic resonance imaging of the lesion revealed a hypointense area on T1-weighted images and a hyperintense area on T2-weighted and abnormal diffusion-weighted images. A diagnosis of recurrent petrous apex cholesteatoma was made. The patient was treated by exteriorization using an endoscopic endonasal approach. The patient is in remission and doing well. The ideal treatment of PBC is complete excision, though exteriorization using an endoscopic endonasal approach is considered a second option when excision is not possible.

Patulous Eustachian Tube Patients With Respiratory Fluctuation of Tympanic Membrane in Both Sitting and Supine Positions: A Sign of Severity of Disease?

OBJECTIVE: The aim is to report four cases of patulous Eustachian tube (PET) patients with respiratory fluctuation of the tympanic membrane (TM) even in the supine position, and to examine the frequency and characteristics of such patients. PATIENTS: There were 195 ears (99 right ears and 96 left ears) from 146 cases (56 male and 90 female subjects aged 8-88, average 48.0 ±â€Š18.9 yrs) diagnosed with definite PET by diagnostic criteria proposed by Japan Otologic Society (JOS) between January 2017 and December 2019 at Sen-En Rifu Hospital. Patients who presented with respiratory fluctuation of the TM in both the sitting and supine positions were examined. MAIN OUTCOME MEASURES: Clinical patient records, the severity of subjective symptoms (PET handicap inventory-10 [PHI-10]), objective ET function tests (tubo-tympano-aerodynamic graphy [TTAG] and sonotubometry), and sitting three-dimensional computed tomography (3-D CT) were analyzed. RESULTS: Six ears (3.1%) of four cases (2.7%) exhibited respiratory fluctuation of the TM, even in the supine position. In these six ears (four cases), the PHI-10 score ranged from 16 to 36 with three ears exhibiting PHI-10 score equal to or exceeding 26 (in the category of severe handicap). Sitting CT indicated the findings of completely open ET in only two ears. All ears but one were managed by conservative treatment. CONCLUSION: Respiratory fluctuation of the TM in both the sitting and supine positions was observed in 2.7% of the definite PET patients. Surprisingly, such findings can be an indication of neither the subjective nor objective severity of the disease. Therefore, even for PET patients with such findings, surgery should not be immediately proposed, but rather, conservative management should be undertaken first.

Usage Patterns of CT and MRI in the Evaluation of Otologic Disease.

OBJECTIVE: To evaluate the current trends and usage patterns of radiographic imaging for otologic disease by specialty, length of practice, practice setting, geographic region, and pediatric volume. STUDY DESIGN: Cross-sectional study. SETTING: Survey of physicians. SUBJECTS: General Otolaryngologists and Otologists/Neurotologists (O/N) of the American Academy of Otolaryngology - Head and Neck Surgery (AAO-HNS). METHODS AND OUTCOME MEASURES: An electronic questionnaire was distributed to AAO-HNS members. Respondents were separated into groups by specialty, length of practice, practice setting, region, and pediatric exposure. Chi-square tests were performed for the determination of significance. RESULTS: The survey was sent to 5,168 members of AAO-HNS. The response rate was 10.6% (n = 546) and 18.1% for only O/N (n = 143). Most respondents were generalists (74%), in practice >20 years (51%), with a primarily adult practice (95%). O/N were more often academics (44 versus 17% combined, 40% private; p < 0.001) and saw fewer children (80 fewer than 25%; p < 0.001). Compared with generalists, O/N were more likely to respond with more frequent and earlier magnetic resonance imaging (MRI) utilization in the workup of the majority of otologic diseases. Significant differences in usage patterns for various conditions were demonstrated across all categories, but specialty training was the most common. Generalists (34 versus 12% of O/N; p < 0.001), physicians practicing >20 years (32 versus 18% of < 5 yrs; p = 0.006), and private practice physicians (34 versus 14-20% of others; p < 0.001) relied more heavily on the radiology report to interpret MRI scans. CONCLUSION: Subspecialty training seems to be the main variable correlating with significant differences in the use of MRI and computed tomography imaging in patients with otologic disease.

The use of near infrared fluorescence imaging with indocyanine green for vascular visualization in caudal auricular flaps in two cats.

OBJECTIVES: To describe the use of near infrared fluorescence (NIRF) imaging with indocyanine green (ICG) for vascular visualization in two caudal auricular axial pattern flaps (APF). ANIMALS: Two client-owned cats with upper eyelid masses. STUDY DESIGN: Clinical case report. METHODS: Wide surgical excision with enucleation was performed by using a caudal auricular APF for closure. Flap margins and perforating artery location were approximated with anatomical landmarks. The caudal auricular artery origin was then visualized percutaneously by using an exoscope with NIRF camera and light source after a single 2.5-mg dose of IV ICG. Margins were adjusted as required. The flaps were routinely elevated with continued intraoperative visualization of the artery and rotated to complete closure. RESULTS: After IV ICG administration, fluorescence was initially visualized after 15 to 18 seconds and remained visible for up to 26 minutes. The achieved visualization led to flap margin adjustments in cat 1. Both cats recovered with minimal flap congestion, excellent hair regrowth, and no long-term complications (>186 days). Cat 1 experienced 100% flap survival. Cat 2 experienced 10% partial thickness flap necrosis, but revision was not required, and the flap was healed at recheck 85 days postoperatively. CONCLUSION: The use of ICG for APF vessel visualization prior to and during flap elevation resulted in transcutaneous visualization of the perforating vessel and improved awareness of vessel location intraoperatively. These two cats experienced excellent flap survival without major complications. This report highlights the potential benefits of ICG NIRF in APF for animals undergoing reconstructive surgery.

Endolymphatic hydrops mimicking obstructive Eustachian tube dysfunction: preliminary experience and literature review.

PURPOSE: Aural fullness is a common symptom of middle ear diseases, most importantly Eustachian tube dysfunction (ETD). Yet, aural fullness may also be caused by inner ear disorders, such as hydropic ear diseases. Here, we report our experience with endolymphatic hydrops (EH) mimicking ETD. Furthermore, we review the literature related to (i) EH as a differential diagnosis of symptoms suggesting ETD and (ii) the pathophysiology and treatment of aural fullness due to inner ear disorders. METHODS: We retrospectively included adult patients with aural fullness as chief complaint and radiographically diagnosed EH. Hearing and Eustachian tube function were assessed using audiometry, tympanometry, and tubomanometry. Primarily suspected ETD was treated by balloon dilatation of the Eustachian tube (BDET). The endolymphatic space of the inner ear was imaged using gadolinium-enhanced MRI (Gd-MRI) including a 3D-real inversion-recovery sequence after intravenous gadolinium administration. RESULTS: We report three affected ears of two patients (two females, age 42 and age 51) with aural fullness as chief complaint. Audiometry of main speech frequencies was normal in all affected ears. In one ear, there was a type A tympanogram and in two ears, there was a type B tympanogram. In both patients, medical treatment for ETD and BDET were unsuccessful. Gd-MRI of the inner ears revealed cochlear EH in 3/3 ears affected by aural fullness, but not in the unaffected ear. CONCLUSION: EH may underlay cases with aural fullness and could in these cases explain unsuccessful treatment for ETD. As ETD is often treated by invasive procedures, distinguishing ETD from EH as the underlying cause of aural fullness is important. Our findings raise the question whether Gd-MRI to rule out EH is indicated in patients with unexplained aural fullness, in particular after unsuccessful interventional treatment for ETD.

Measurement method for external auditory canal and clinical application in congenital aural stenosis.

OBJECTIVE: To describe a measurement method for external auditory canal (EAC), especially in congenital aural stenosis (CAS). METHODS: High-resolution CT (HRCT) datasets of CAS were imported into the MIMICS 15.0 software for image processing. We used two methods to evaluate the degree of CAS. One is sagittal reconstruction measurement method, the minor axis of the bony ear canal was measured in each layer using sagittal reconstruction. The other is Matlab procedure calculation, we calculated the midpoint axis values of the EAC in each Frankfurt plane. Finally, we compared the minimum value of each method, and verified the sagittal reconstruction measurement method retrospectively in the CAS cases without cholesteatoma who had undergone meatoplasty. RESULTS: Twenty CAS cases were selected using the sagittal reconstruction measurement method and Matlab procedure calculation to evaluate the degree of CAS. The mean age was 9.55 ± 2.85 years old (range: 6-15). The mean degree of CAS was 2.09 ± 0.50 mm by sagittal reconstruction measurement method and 2.03 ± 0.58 mm by Matlab procedure calculation. There were no significant differences in the two groups (t = -1.371, p = 0.186). A total of 94 HRCT datasets were imported into MIMICS for verification. The mean age was 11.66 ± 6.56 years old (range: 6-39). Mean stenosis of EAC at surgery was 2.88 ± 0.93 mm (range: 1-4) by using sagittal reconstruction measurement method. CONCLUSIONS: Matlab procedure calculation is precise but relatively complicated and is only for scientific research. The sagittal reconstruction measurement method to calculate the most stenotic part of the bony ear canal is relatively simple and accurate to evaluate the degree of CAS. In cases of CAS without cholesteatoma, the precise measurement was critical for the next consultation.

MRI of the Internal Auditory Canal, Labyrinth, and Middle Ear: How We Do It.

MRI is firmly established as an essential modality in the imaging of the temporal bone and lateral skull base. It is used to evaluate normal anatomic structures, evaluate for vestibular schwannomas, assess for inflammatory and/or infectious processes, and detect residual and/or recurrent cholesteatoma. It is also extensively used in pre- and postoperative evaluations, particularly in patients with vestibular schwannomas and candidates for cochlear implantation. Nevertheless, despite the widespread use of MRI for these purposes, many radiologists remain unfamiliar with the complex anatomy and expected imaging findings with such examinations. The purpose of this review is to provide an overview of the most useful MRI sequences for internal auditory canal and labyrinthine imaging, review the relevant anatomy, and discuss the expected appearances of the most commonly encountered pathologic entities. In addition, the features at pre- and postprocedural MRI will be discussed to help ensure that diagnostic radiologists may be of greatest use to the ordering physicians. © RSNA, 2020.

Inner ear MRI: is it always useful to manage intravenous contrast? / Resonancia magnética de conducto auditivo interno: ¿es siempre útil administrar contraste intravenoso?

OBJECTIVE: To evaluate the added value of administering intravenous contrast (IVC) routinely to the MRI of patients with audiovestibular symptoms in the assessment of a neuroradiologist and a resident. MATERIALS AND METHODS: Retrospective study including patients who had an inner ear MRI for two months. Two radiologists reviewed independently and blinded the images. A first assessment was made analyzing just the sequences acquired without contrast and then a second evaluation of all the sequences, including post-contrast T1 sequences. The interobserver correlation and the correlation between MRI findings and the reason for requesting the study were calculated. RESULTS: 40 patients were included. The range age was 36-80 years. The most frequent reason for request the MRI was hearing loss (52.5%). Neuroradiologist without IVC found 82.5% of extraotic pathology and 17.5% of otic pathology, highlighting the neurinoma of the VIII pair (7.5%); ossifying labyrinthitis, retrofenestrated otosclerosis and cholesteatoma. After IVC administration, findings were similar. The resident identified otic pathology in 5% in baseline sequences and 20% using CIV. The interobserver correlation using IVC was excellent (0.97), but weak without IVC (0.52). There was a correlation between the reasons for request the MRI and the findings in the ears, both in protocols without IVC (p = 0.004) and in protocols with IVC (p = 0.002). CONCLUSION: Inner ear MRI without contrast gives relevant information to assess audiovestibular symptoms. The use of IVC increases the degree of confidence in a novel radiologist, while in the expert its use is less relevant. A protocol should be proposed in which gadolinium is used in selected patients.

Rhythmic Wave Patterns on Ambient Pressure Tympanometry in Patients With Objective Tinnitus-associated Pathologies.

OBJECTIVE: To introduce the concept of ambient pressure tympanometry (APT) and its association with pathologies that may present with objective tinnitus. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. SUBJECTS AND METHODS: Audiologists performed APT on adult patients as part of routine audiological testing. Ears with myoclonus and patulous Eustachian tube (PET) were identified via review of patient history and physical examination. All other conditions were verified via computed tomography (CT) temporal bone imaging. Ears with conditions that could impair tympanic membrane compliance, such as otosclerosis or tympanic membrane perforation, were excluded. APT findings were analyzed via a novel algorithm. RESULTS: A radiographic finding associated with objective tinnitus was confirmed in 67 ears that underwent CT imaging; 45 (67%) of these ears displayed rhythmic APT wave patterns. These included 28 ears with superior semicircular canal dehiscence, 4 ears with sigmoid sinus dehiscence, 6 ears with internal carotid artery dehiscence, 4 ears with glomus tumor, and 3 ears with encephalocele. In addition, we identified three ears with myoclonus and one ear with PET. In a subset of 30 ears with objective tinnitus symptoms that underwent CT imaging, 22 displayed rhythmic waves; of these 22 ears, 20 (91%) had a radiographic finding associated with objective tinnitus. CONCLUSIONS: Rhythmic APT wave patterns are common and may be associated with numerous temporal bone pathologies that may present with objective tinnitus. APT is a simple, rapid, and widely available tool that warrants further study to determine its value in screening of these otologic conditions.

Automated diagnosis of ear disease using ensemble deep learning with a big otoendoscopy image database.

BACKGROUND: Ear and mastoid disease can easily be treated by early detection and appropriate medical care. However, short of specialists and relatively low diagnostic accuracy calls for a new way of diagnostic strategy, in which deep learning may play a significant role. The current study presents a machine learning model to automatically diagnose ear disease using a large database of otoendoscopic images acquired in the clinical environment. METHODS: Total 10,544 otoendoscopic images were used to train nine public convolution-based deep neural networks to classify eardrum and external auditory canal features into six categories of ear diseases, covering most ear diseases (Normal, Attic retraction, Tympanic perforation, Otitis externa±myringitis, Tumor). After evaluating several optimization schemes, two best-performing models were selected to compose an ensemble classifier, by combining classification scores of each classifier. FINDINGS: According to accuracy and training time, transfer learning models based on Inception-V3 and ResNet101 were chosen and the ensemble classifier using the two models yielded a significant improvement over each model, the accuracy of which is in average 93·67% for the 5-folds cross-validation. Considering substantial data-size dependency of classifier performance in the transfer learning, evaluated in this study, the high accuracy in the current model is attributable to the large database. INTERPRETATION: The current study is unprecedented in terms of both disease diversity and diagnostic accuracy, which is compatible or even better than an average otolaryngologist. The classifier was trained with data in a various acquisition condition, which is suitable for the practical environment. This study shows the usefulness of utilizing a deep learning model in the early detection and treatment of ear disease in the clinical situation. FUND: This research was supported by Brain Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT(NRF-2017M3C7A1049051).