The Efficacy of Color-Mapped Diffusion-Weighted Images Combined With CT in the Diagnosis and Treatment of Cholesteatoma Using Transcanal Endoscopic Ear Surgery

Recent advances in Otology: Current landscape and future direction

Hearing is an essential sensation, and its deterioration leads to a significant decrease in the quality of life. Thus, great efforts have been made by otologists to preserve and recover hearing. Our knowledge regarding the field of otology has progressed with advances in technology, and otologists have sought to develop novel approaches in the field of otologic surgery to achieve higher hearing recovery or preservation rates. This requires knowledge regarding the anatomy of the temporal bone and the physiology of hearing. Basic research in the field of otology has progressed with advances in molecular biology and genetics. This review summarizes the current views and recent advances in the field of otology and otologic surgery, especially from the viewpoint of young Japanese clinician-scientists, and presents the perspectives and future directions for several topics in the field of otology. This review will aid next-generation researchers in understanding the recent advances and future challenges in the field of otology.

Selection of a Surgical Approach for Middle Ear Cholesteatoma Based on the Fusion Images of Non-Echo Planar Diffusion-Weighted MRI and CT

PURPOSE

This study aimed to explore the ability of fusion images of non-echo planar diffusion-weighted magnetic resonance imaging (non-EPI-DWI MRI) and computed tomography (CT) to accurately locate cholesteatoma and plan the surgical approach.

METHODS

In the first part, 41 patients were included. Their CT images and non-EPI DWMRI images were fused. The scope of cholesteatoma in the fusion image was compared with that in the surgical video to evaluate the capability to locate cholesteatoma. A total of 229 patients were included in the second part, and they were divided into 2 groups. We chose the surgical approach for the CT group and the fusion group, and compared the accuracy of surgical approaches in the CT group and the fusion group using the surgical records.

RESULTS

The location of cholesteatoma shown in the fusion images was almost identical to that observed during the operation (kappa = .862). The overall specificity and sensitivity of the fusion images in locating cholesteatoma were 94.12% and 93.06%, respectively. The accuracy of surgical approach selection based on the fusion images (99.02%) was higher than that of surgical approach selection based on the CT images (85.83%).

CONCLUSION

It is recommended that the fusion images be used to locate the range of the cholesteatoma before operation.

"Transcanal view" computed tomography reformat: Applications for transcanal endoscopic ear surgery

PURPOSE

Transcanal endoscopic ear surgery (TEES) is an increasingly used surgical approach for otologic surgeries, but no en face preoperative imaging format currently exists. We aim to assess the utility of a transcanal high resolution computed tomography (HRCT) reformat suitable for TEES preoperative planning.

MATERIALS AND METHODS

Preoperative HRCTs of patients with middle ear pathologies (cholesteatoma, otosclerosis, and glomus tympanicum) who underwent TEES were obtained. Axial image series were rotated and reformatted -90 or +90 degrees for left and right ear surgeries, respectively, where additional rotation along the left-right axis was performed to align the transcanal series with the plane of the external auditory canal. Quantitative measurements of middle ear structures were recorded. Consecutive transcanal reformatted sections were then reviewed to identify critical middle ear anatomy and pathology with corresponding TEES cases.

RESULTS

The aforementioned methodology was used to create three transcanal view HRCTs. The mean left-right axis degree of rotation was 4.0 ± 2.2 degrees. In the cholesteatoma transcanal HRCT, areas of cholesteatoma involvement in middle ear compartments (e.g. epitympanum) and eroded ossicles were successfully identified in the corresponding case. In the otosclerosis transcanal HRCT, areas for potential otosclerotic involvement were visualized such as the round window as well as a low-hanging facial nerve. In the glomus tympanicum transcanal HRCT, the span of the glomus tympanicum was successfully visualized in addition to a high riding jugular bulb.

CONCLUSION

A transcanal HRCT reformat may aid preoperative planning for middle ear pathologies. This novel reformat may help highlight patient-specific anatomy.

Patency of Anterior Epitympanic Space and Surgical Outcomes After Endoscopic Ear Surgery for the Attic Cholesteatoma

OBJECTIVE

To reveal the patency of the anterior epitympanic space (AES) and the surgical outcomes after transcanal endoscopic ear surgery (TEES) for attic cholesteatoma with a classification of anatomical variation of the AES.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Seventy-four ears (72 patients with early-stage (I or II) attic cholesteatoma) aged between 16 and 85 years (mean: 48.9 yr) who underwent TEES between 2015 and 2017 were analyzed.

INTERVENTION

Tympanoplasty with atticoantrotomy was performed with TEES. TEES was performed using a rigid endoscope with an outer diameter of 2.7 mm.

MAIN OUTCOME MEASURE

The tensor fold in the AES anatomical classification, the postoperative patency of the AES evaluated by computer tomography images, and hearing outcomes based on the American Academy of Otolaryngology and Head and Neck Surgery criteria were evaluated after TEES for early-stage attic cholesteatoma.

RESULTS

There were 14 (18.9%) ears with a vertical tensor fold orientation, 29 (39.2%) ears with an oblique orientation, and 29 (39.2%) ears with a horizontal orientation. The total postoperative patency rate in the AES was 81.0%, without any significant difference in the anatomical variation in the AES, whereas the rate of preoperative complete tensor fold was 90.5%. Cholesteatoma recurrence was observed in three cases (4.1%), and all recurrent cases had obstructed AES. No significant difference was found in the postoperative air-bone gap regardless of the patency of the AES.

CONCLUSION

Our findings indicate that TEES is useful in restoring ventilation in the AES, resulting in favorable management of cholesteatoma.

A Novel Surgery Classification for Endoscopic Approaches to Middle Ear Cholesteatoma

This study aimed to develop a novel surgery classification for an endoscopic approach to middle ear cholesteatoma. We retrospectively analyzed the surgical approaches and outcomes of patients with middle ear cholesteatoma. Middle ear cholesteatoma surgeries were divided into four types and two special types as follows: type I, attic retraction pocket, which only requires tympanostomy tube placement or retraction pocket resection and cartilage reconstruction; type II, cholesteatoma which is limited to the attic or in which endoscopy can confirm complete removal of mastoid cholesteatoma lesions, including type II a, requiring only use of a curette, and type II b, requiring use of an electric drill or chisel; type III, cholesteatoma not limited to the attic, in which endoscopy cannot confirm complete removal of mastoid cholesteatoma lesions, requiring the combined use of endoscope and microscope to perform endoscopic tympanoplasty and "Canal Wall Up" mastoidectomy; type IV, extensive involvement of mastoid cavity cholesteatoma lesions and/or cases with a potential risk of complications, removal of which can only be performed under a microscope for "Canal Wall Down" mastoidectomy. In addition, there were two special types: "difficult external auditory canal" and congenital cholesteatoma in children. In our system, type I and type II middle ear cholesteatoma surgery was completely performed under an endoscope alone. However, estimating the extent of the lesions, determining the choice of mastoid opening and reestablishing ventilation are the key points for an endoscopic approach to middle ear cholesteatoma. The classification of endoscopic middle ear cholesteatoma surgery may benefit the selection of surgical indications.

Surgical mapping of middle ear cholesteatoma with fusion of computed tomography and diffusion-weighted magnetic resonance images: Diagnostic performance and interobserver agreement

OBJECTIVE

To assess the diagnostic performance in detecting primary cholesteatoma at various anatomical subsites using Computed Tomography (CT), Diffusion-weighted Magnetic Resonance Imaging (DWMRI) and Fusion of CT and DWMRI (Fusion CT-MRI) images.

STUDY DESIGN

A retrospective study of 22 children identified from a prospective database of surgically treated cholesteatoma cases over a five year period. All cases underwent pre-operative CT, non-echo planar DWMRI and Fusion CT-DWMRI, and with clearly documented surgical findings. For each imaging modality, two radiologists scored for the presence or absence of cholesteatoma with confidence levels at different anatomical subsites. The radiologists were blinded to the surgical findings to which their findings were compared.

SETTING

Large Teaching Hospital in London.

PATIENTS

22 children with cholesteatoma confirmed surgically.

INTERVENTION

CT, DWMRI imaging and fusion CT-MRI.

MAIN OUTCOME MEASURE

Diagnostic performance of subsite localisation of cholesteatoma by CT, DWMRI and fusion CT-MRI imaging with intra-operative findings.

RESULTS

Twenty-two patients were included (12 women and 10 men). The median age of patients was 11 years. When considering all subsites combined, the result for all imaging methods suggested 'good' agreement between both observers. When all subsites were examined together, all methods had relatively high sensitivity values (87% for CT vs 84% for DWMRI vs 85% for fusion CT-DWMRI). Specificity was highest with fusion CT-DWMRI (46% for CT vs 76% for DWMRI vs 97% for fusion CT-DWMRI), as was accuracy (66% for CT vs 80% for DWMRI vs 91% for fusion).

CONCLUSIONS

Our study has demonstrated that fusion CT-DWMRI is superior to DWMRI or CT separately in localizing cholesteatoma at various middle ear cleft subsites and bony relations, making it a valuable tool for surgical planning.

Transcanal Computed Tomography Views for Transcanal Endoscopic Lateral Skull Base Surgery: Pilot Cadaveric Study

Objective  Transcanal endoscopic operative approaches provide for a minimally invasive surgical portal to the lateral skull base. Traditional preoperative imaging evaluation involves computed tomography (CT) acquisition in the axial and coronal planes that are not optimized for the transcanal surgical corridor. Herein, we describe a novel CT-based "transcanal view" for preoperative surgical planning and intraoperative navigation. Study Design  Present study is a cadaveric imaging study. Methods  Cadaveric temporal bones ( n  = 6) from three specimens underwent high-resolution CT (0.625 mm slice thickness). Using three-dimensional (3D) Slicer 4.8, reformatted "transcanal" views in the plane of the external auditory canal (EAC) were created. Axial and coronal reformats were used to compare and measure distances between anatomic structures in the plane of the EAC. Results  The degree of oblique tilt for transcanal CT reformats was 6.67 ± 1.78 degrees to align the EAC in axial and coronal planes. Anticipated critical landmarks were identified easily using the transcanal view. Mean values were 8.68 ± 0.38 mm for annulus diameter, 9.5 ± 0.93 mm for isthmus diameter, 10.27 ± 0.73 mm for distance between annulus and isthmus, 2.95 ± 0.13 mm for distance between annulus and stapes capitulum, 5.12 ± 0.35 mm for distance between annulus and mastoid facial nerve, and 19.54 ± 1.22 mm for EAC length. Conclusion  This study is the first to illustrate a novel "transcanal" CT sequence intended for endoscopic lateral skull base surgery. Future studies may address how incorporation of a transcanal CT reformat may influence surgical decision making.

The Antrum-Malleus-Tegmen Score: A Pilot Study Assessing Preoperative Radiographic Predictors for Transcanal Endoscopic Cholesteatoma Dissection

OBJECTIVE

Identify features on computed tomography (CT) that predict mastoidectomy conversion (MC) during transcanal endoscopic ear surgery (TEES).

STUDY DESIGN

Retrospective case-control.

SETTING

University otology practice.

PATIENTS

Consecutive patients with cholesteatoma.

INTERVENTION

TEES cholesteatoma dissection versus those requiring MC.

MAIN OUTCOME MEASURES

Antrum opacification, depth of scutum involvement, and erosion of the mastoid trabeculae, ossicular chain, and tegmen were evaluated. Univariable and multivariable regression analysis was performed. The Antrum-Malleus-Tegmen (AMT) score was created using receiver operating characteristic curves to assess feasibility of performing TEES for cholesteatoma dissection.

RESULTS

There were 39 TEES and 19 MC cases. Groups had similar age (median 28.5 yr), gender, laterality, and revision surgery status. Median surgical time for MC cases was longer than TEES (231 min vs. 171 min, p < 0.001). Radiographic predictors of MC by multivariable regression included antrum opacification (p = 0.036), malleus erosion (p = 0.044), and tegmen erosion (p = 0.023). The AMT score predicted the feasibility of TEES without MC with a sensitivity of 90% and specificity of 75% when ≥2 of the following conditions were met on preoperative CT: intact tegmen, intact malleus, and absence of antrum opacification.

CONCLUSIONS

An aerated antrum, intact malleus, and intact tegmen suggest that TEES cholesteatoma dissection without the need for mastoidectomy is highly likely. A score of ≥2 on the AMT score predicts this with a positive predictive value of 88% and negative predictive value of 78%.