Postoperative diffusion weighted MRI and preoperative CT scan fusion for residual cholesteatoma localization

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

OBJECTIVES

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.

MATERIALS AND METHODS

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.

RESULTS

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%.

CONCLUSION

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.

CLINICAL RELEVANCE STATEMENT

The proposed algorithm addresses the primary limitations of MRI in localizing anatomic sites within the temporal bone.

KEY POINTS

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.

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.

Comparison of the Utility of High-Resolution CT-DWI and T2WI-DWI Fusion Images for the Localization of Cholesteatoma

BACKGROUND AND PURPOSE

Cholesteatoma is an aggressive disease that may lead to hearing impairment. This study aimed to compare the utility of high-resolution CT and TSE-DWI fusion images with that of T2WI and TSE-DWI fusion images in the localization of middle ear cholesteatoma.

MATERIALS AND METHODS

Seventy-one patients with middle ear cholesteatoma were retrospectively recruited. High-resolution CT, T2WI with fat suppression, and TSE-DWI scans were obtained, and image fusion was performed using a 3D reconstruction postprocessing workstation to form CT-DWI and T2WI-DWI fusion images. The quality of the 2 fused images was subjectively evaluated using a 5-point Likert scale with the horizontal semicircular canal transverse position as the reference. Receiver operating characteristic analysis was performed, and the diagnostic efficacies of CT-DWI and T2WI-DWI fusion images in localizing middle ear cholesteatoma were calculated.

RESULTS

The overall quality of T2WI-DWI fusion images was slightly higher than that of CT-DWI fusion images (P < .001), and the semicircular canal was slightly less clear on T2WI-DWI than on CT-DWI (P < .001). No statistical difference was found in the diagnostic confidence between them. In the localization of middle ear cholesteatoma, the accuracy, sensitivity, and specificity of T2WI-DWI fusion images and CT-DWI fusion images were equivalent for involvement of the attic, tympanic cavity, mastoid antrum, and mastoid process, with no statistically significant differences.

CONCLUSIONS

T2WI-DWI fusion images could replace CT-DWI in the preoperative selection of surgical options for middle ear cholesteatoma.

[Combination of CT and MRT in the diagnostic of middle ear cholesteatoma. Fusion technology is precise localization tool]

Computed tomography (CT) and magnetic resonance imaging (MRI) methods of the middle ear cholesteatoma diagnostic have its advantages and disadvantages. Fusion technology is a post-processing process of CT and MRI images. Its main advantage is the localization of MR-hyperintensive cholesteatoma within the bony anatomical structures obtained on CT, which provides the surgeon with important information both before planning the primary surgical intervention and during a second revision for recurrent cholesteatoma.

Correlation of pre-operative computed tomography, intra-operative findings and surgical outcomes in revision tympanomastoidectomy

OBJECTIVE

To correlate pre-operative computed tomography findings, intra-operative details and surgical outcomes with cholesteatoma recurrence in revision tympanomastoidectomy.

METHODS

This retrospective, non-randomised, single-institution cohort study included 42 patients who underwent pre-operative computed tomography imaging and revision surgery for recurrent chronic otitis media. Twelve disease localisations noted during revision surgery were correlated with pre-operative temporal bone computed tomography scans. A matched pair analysis was performed on patients with similar intra-operative findings, but without pre-operative computed tomography scans.

RESULTS

Pre-operative computed tomography identified 25 out of 31 cholesteatoma recurrences. Computed tomography findings correlated with: recurrent cholesteatoma when attic opacification and ossicular chain involvement were present; and revision surgery type. Sinodural angle disease, posterior canal wall erosion and dehiscent dura were identified as predictors of canal wall down tympanomastoidectomy. Patients with pre-operative computed tomography scans had a higher rate of cholesteatoma recurrence, younger age at diagnosis of recurrent disease, more revision surgical procedures and less time between previous and revision surgical procedures (all p < 0.05).

CONCLUSION

Pre-operative imaging and intra-operative findings have important clinical implications in revision surgery for chronic otitis media. Performing pre-operative computed tomography increases diagnosis accuracy and reduces the time required to diagnose recurrent disease.

Cholesteatoma Localization Using Fused Diffusion-Weighted Images and Thin-Slice T2 Weighted Images

BACKGROUND

Fusion of diffusion-weighted imaging (DWI) to computed tomography (CT) has been touted as a possible technique to improve cholesteatomas localization. This study set out to assess the ability of DWI images fused with thin-slice heavily T2-weighted images to similarly localize surgically-confirmed cholesteatomas.

MATERIALS AND METHODS

A retrospective review was completed of consecutive patients that underwent MR temporal bone imaging (9/2011-3/2020) with both DWI and thin-slice T2-weighted imaging. Included patients underwent surgical resection of primary or recidivistic cholesteatoma after preoperative MR imaging. A neuroradiologist, who was blinded to operative and clinical notes, localized each lesion on both DWI and fused DWI-T2 images in 11 anatomic subdivisions of the temporal bone. Surgical confirmation of cholesteatoma location was used as the gold standard for comparison.

RESULTS

Of 24 included examinations, the average age at time of MR was 48.2 ± 24.7 years; 12/24 (50.0%) were female. Five of 24 had primary cholesteatoma, while the remainder had recidivistic disease. Sensitivity, specificity, and accuracy of unfused DWI images were 52.1%, 88.9%, and 75.8%, respectively. Sensitivity, specificity, and accuracy of fused DWI-T2 images were 57.1%, 94.8%, and 81.8%, respectively.

CONCLUSION

Fused DWI-T2 images outperformed unfused DWI images in the anatomic localization of temporal bone cholesteatomas. This method represents a potential alternative to MR-CT fusion for pre-operative cholesteatoma evaluation, and warrants future investigations. Opposed to MR-CT fusion, this method only necessitates MR sequences and removes the need for additional CT acquisition.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:E1662-E1667, 2021.

Novel Radiologic Approaches for Cholesteatoma Detection: Implications for Endoscopic Ear Surgery

Technological advancement in computed tomography (CT) and MRI has improved cholesteatoma detection rates considerably in the past decade. Accurately predicting disease location and extension is essential for staging, planning, and preoperative counseling, in particular in the newer approach of endoscopic ear surgery. Improved sensitivity and specificity of these radiological methods may allow the surgeon to confidently monitor patients, therefore avoiding unnecessary surgery. This article outlines recent advances in CT and MRI technology and advantages and disadvantages of the newer techniques. Emphasis on improving the feedback loop between the radiologist and surgeon will increase the accuracy of these new technologies.

A case report of rare intraperitoneal cholesteatoma diagnosed and treated through multidisciplinary collaboration

55‐year‐old female patient with abdominal distension and poor appetite for 3 months was diagnosed as intraperitoneal cholesteatoma by imaging findings and histological tests. Patient has received surgical resection and recovered well after operation.

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.

The utility of computed tomography and diffusion-weighted magnetic resonance imaging fusion in cholesteatoma: illustration with a UK case series

OBJECTIVE

Post-processing imaging techniques allow high-resolution computed tomography and diffusion-weighted magnetic resonance imaging of the temporal bone to be superimposed and viewed simultaneously (fusion imaging). This study aimed to highlight the practical utility of fusion imaging for disease localisation and evaluation in a UK case series of primary and post-operative cholesteatoma.

METHOD

Fusion of computed tomography and diffusion-weighted magnetic resonance b1000 images was performed using specific software. Axial computed tomography images and coronal b1000 images were selected for fusion.

RESULTS

A case series of primary and post-operative cholesteatoma in which computed tomography and magnetic resonance imaging fusion assisted the management of both the patient pathway and surgical approach is reviewed.

CONCLUSION

Computed tomography and magnetic resonance imaging fusion can assist in pre-operative surgical planning and patient counselling through assessment of disease in both primary and revision scenarios. Computed tomography and magnetic resonance imaging fusion can assist the operative surgeon through accurate localisation that can influence both the operative technique and optimise operation theatre utilisation.