Contemporary non-echo-planar diffusion-weighted imaging of middle ear cholesteatomas

Improved reconstruction for highly accelerated propeller diffusion 1.5 T clinical MRI

PURPOSE

Propeller fast-spin-echo diffusion magnetic resonance imaging (FSE-dMRI) is essential for the diagnosis of Cholesteatoma. However, at clinical 1.5 T MRI, its signal-to-noise ratio (SNR) remains relatively low. To gain sufficient SNR, signal averaging (number of excitations, NEX) is usually used with the cost of prolonged scan time. In this work, we leveraged the benefits of Locally Low Rank (LLR) constrained reconstruction to enhance the SNR. Furthermore, we enhanced both the speed and SNR by employing Convolutional Neural Networks (CNNs) for the accelerated PROPELLER FSE-dMRI on a 1.5 T clinical scanner.

METHODS

Residual U-Net (RU-Net) was found to be efficient for propeller FSE-dMRI data. It was trained to predict 2-NEX images obtained by Locally Low Rank (LLR) constrained reconstruction and used 1-NEX images obtained via simplified reconstruction as the inputs. The brain scans from healthy volunteers and patients with cholesteatoma were performed for model training and testing. The performance of trained networks was evaluated with normalized root-mean-square-error (NRMSE), structural similarity index measure (SSIM), and peak SNR (PSNR).

RESULTS

For 4 × under-sampled with 7 blades data, online reconstruction appears to provide suboptimal images-some small details are missing due to high noise interferences. Offline LLR enables suppression of noises and discovering some small structures. RU-Net demonstrated further improvement compared to LLR by increasing 18.87% of PSNR, 2.11% of SSIM, and reducing 53.84% of NRMSE. Moreover, RU-Net is about 1500 × faster than LLR (0.03 vs. 47.59 s/slice).

CONCLUSION

The LLR remarkably enhances the SNR compared to online reconstruction. Moreover, RU-Net improves propeller FSE-dMRI as reflected in PSNR, SSIM, and NRMSE. It requires only 1-NEX data, which allows a 2 × scan time reduction. In addition, its speed is approximately 1500 times faster than that of LLR-constrained reconstruction.

Performance of Non-EPI DW MRI for Pediatric Cholesteatoma Follow-Up

OBJECTIVE

To evaluate the accuracy, sensitivity, and specificity of nonecho planar (non-EPI) diffusion-weighted (DW) magnetic resonance imaging (MRI) to detect residual cholesteatoma in children.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary comprehensive hospital.

METHODS

Children operated on for a first-stage cholesteatoma procedure from 2010 to 2019 were included. MRIs were performed with non-EPI DW sequences. Initial reports were collected, indicating the presence or absence of hyperintensity suggestive of cholesteatoma. Three hundred twenty-three MRIs were correlated with the subsequent surgery (66%) or year-later MRI (21%), or were considered accurate if performed 5 years or more after the last surgery (13%). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging procedure for the detection of cholesteatoma were calculated.

RESULTS

Two hundred twenty-four children with mean age of 9 ± 4 years old presented with cholesteatoma. MRIs were performed 27 ± 24 months after surgery. Residual cholesteatoma was diagnosed in 35%. The sensitivity, specificity, PPV, and NPV of MRI were 62%, 86%, 74%, and 78%, respectively. Accuracy, sensitivity, and specificity increased significantly over time (multivariate analysis). The mean delay after last surgery was of 30 ± 2.0 months for accurate MRI (true positive or negative) versus 17 ± 2.0 months for nonaccurate (false positive or negative) MRIs (p < .001).

CONCLUSION

However, long the delay after the last surgery, the sensitivity of non-EPI diffusion sequence MRI in children has limitations for the detection of residual cholesteatoma. Surveillance for residual cholesteatoma should incorporate findings at primary surgery, surgeon experience, a low threshold for second-look procedures, and routine imaging.

Localization Evaluation of Primary Middle Ear Cholesteatoma With Fusion of Turbo Spin-Echo Diffusion-Weighted Imaging and High-Resolution Computed Tomography

OBJECTIVE

The aim of the study is to evaluate the application of high-resolution computed tomography (HRCT) and turbo spin-echo diffusion-weighted imaging (TSE-DWI) fusion imaging for localization of middle ear cholesteatomas.

METHODS

Eighty-six patients with clinically suspected middle ear cholesteatomas were enrolled prospectively. Ear TSE-DWI and HRCT scans were performed using a postprocessing workstation to generate a TSE-DWI-CT fusion image. Subsequently, all the enrolled patients received surgical treatment. According to the STAM system (difficult access sites [S], the tympanic cavity [T], the attic [A], and the mastoid [M]), the agreement between the localization of lesions evaluated by HRCT, TSE-DWI, and TSE-DWI-CT fusion images and the intraoperatively recorded localization were computed using Cohen κ statistic.

RESULTS

Based on the pathological results, the enrolled patients were divided into a cholesteatoma (n = 50) and a noncholesteatoma group (n = 36). The area under the receiver operator characteristic curve for diagnosis of cholesteatoma with TSE-DWI-CT fusion imaging was identical to that using the TSE-DWI images (0.924 vs 0.924, P > 0.05), but was significantly higher than that with HRCT imaging (0.924 vs 0.767, P = 0.0005). Furthermore, the diagnostic sensitivity and specificity of TSE-DWI-CT fusion imaging for cholesteatomas were 96.0% and 88.9%, respectively. Depending on whether the cholesteatoma extended to the mastoid, TSE-DWI-CT fusion imaging demonstrated good agreement with the intraoperative record for localization of lesions (κ = 0.808) and had a high accuracy of localization by the STAM system.

CONCLUSIONS

Turbo spin-echo-DWI-CT fusion images have a very high diagnostic value for the preoperative localization of cholesteatomas.

The Clinical Role of Diffusion-Weighted MRI for Detecting Residual Cholesteatoma in Canal Wall up Mastoidectomy

OBJECTIVES

The purpose of this study was to assess the value of the diffusion MRI with the non-echoplanar imaging (Non-EPI) technique for follow-up the post-operative patients to detect residual cholesteatomas.

STUDY DESIGN

This prospective study was performed on 40 patients. All patients were at least one year after Canal Wall Up mastoidectomy surgery for cholesteatoma and scheduled for a second-look surgery.

PATIENTS AND METHODS

This prospective study was performed on 40 patients. All patients were subjected to Canal Wall Up surgery and planned for the second-look operation. After one year as removal of choleasteatoma is uncertain in first surgery. The study done at Tertiary referral centers (Ain shams, Mansoura, and Minia university hospitals), non-echoplanar diffusion MRI (NEP-DWI) technique for follow-up the post-operative patients to detect residual cholesteatomas, then second look surgery done 2 weeks after MRI.

RESULTS

Forty patients underwent MRI with Non-echoplanar diffusion-weighted imaging (NEP-DWI). Twenty-six patients had positive MRI results with the remaining 14 patients had negative results. These results were compared to operative findings. All positive MRI cases showed positive intra-operative findings. Ten of negative MRI cases showed negative intra-operative findings. Four of DWI-negative cases showed small cholesteatomas.

CONCLUSION

The use of NEP-DWI is a valuable tool in detecting residual cholesteatoma that could replace the second look surgery in many cases.

Diagnostic Benefit of High b-Value Computed Diffusion-Weighted Imaging in Patients with Hepatic Metastasis

Diffusion-weighted imaging (DWI) has rapidly become an essential tool for the detection of malignant liver lesions. The aim of this study was to investigate the usefulness of high b-value computed DWI (c-DWI) in comparison to standard DWI in patients with hepatic metastases. In total, 92 patients with histopathologic confirmed primary tumors with hepatic metastasis were retrospectively analyzed by two readers. DWI was obtained with b-values of 50, 400 and 800 or 1000 s/mm² on a 1.5 T magnetic resonance imaging (MRI) scanner. C-DWI was calculated with a monoexponential model with high b-values of 1000, 2000, 3000, 4000 and 5000 s/mm². All c-DWI images with high b-values were compared to the acquired DWI sequence at a b-value of 800 or 1000 s/mm² in terms of volume, lesion detectability and image quality. In the group of a b-value of 800 from a b-value of 2000 s/mm², hepatic lesion sizes were significantly smaller than on acquired DWI (metastases lesion sizes b = 800 vs. b 2000 s/mm²: mean 25 cm³ (range 10-60 cm³) vs. mean 17.5 cm³ (range 5-35 cm³), p < 0.01). In the second group at a high b-value of 1500 s/mm², liver metastases were larger than on c-DWI at higher b-values (b = 1500 vs. b 2000 s/mm², mean 10 cm³ (range 4-24 cm³) vs. mean 9 cm³ (range 5-19 cm³), p < 0.01). In both groups, there was a clear reduction in lesion detectability at b = 2000 s/mm², with hepatic metastases being less visible compared to c-DWI images at b = 1500 s/mm² in at least 80% of all patients. Image quality dropped significantly starting from c-DWI at b = 3000 s/mm². In both groups, almost all high b-values images at b = 4000 s/mm² and 5000 s/mm² were not diagnostic due to poor image quality. High c-DWI b-values up to b = 1500 s/mm² offer comparable detectability for hepatic metastases compared to standard DWI. Higher b-value images over 2000 s/mm² lead to a noticeable reduction in imaging quality, which could hamper diagnosis.

Radiological evaluation of the postsurgical middle ear

OBJECTIVE

The radiological evaluation of the postsurgical middle ear is complex due to the intricate anatomy of this region and the wide variety of procedures and materials used iin middle ear surgery. Knowledge of these factors will enable normal postsurgical changes to be differentiated from complications. This article describes the most common surgical procedures in the middle ear, their indications, and the normal radiological appearance after these procedures. It reviews the most common causes of failure in stapes surgery, in surgery for chronic otitis media, and in surgery for cholesteatoma, suggesting the best imaging method to assess the middle ear in each case.

CONCLUSION

Computed tomography enables the evaluation of prostheses and the aeration of the cavities, whereas magnetic resonance imaging makes it possible to characterize the possible occupation of the cavities and is the technique of choice for the follow-up of closed mastoidectomy for cholesteatomas.

MRI of middle ear cholesteatoma: The importance of observer reliance from diffusion sequences

BACKGROUND AND PURPOSE

Diffusion-weighted imaging(DWI) in MRI has been developed as an important tool for the detection of cholesteatoma. Various DWI sequences are available. This study aims to evaluate the importance of the observer's reliance level for the detection of cholesteatoma.

METHODS

Forty patients meeting the following criteria were included in the study: (1) chronic otitis media, (2) preoperative MRI including various DWI sequences, and (3) middle-ear surgery. The MRI protocol contained the following sequences: (1) axial and (2) coronal echoplanar imaging (EPI) readout-segmented (RESOLVE) DWI with Trace acquisition and (3) coronal non-EPI half-Fourier acquired single-shot turbo spin-echo (HASTE) DWI. Cholesteatoma diagnosis was based on standard diagnostic criteria for cholesteatoma with DWI. Additionally, the radiologists were asked to grade personal reliance on their diagnosis using a Likert-type scale from 1 = very insecure to 5 = very secure.

RESULTS

Axial and coronal RESOLVE DWI showed a sensitivity of 77.3% and a specificity of 72.2%, respectively. The mean reliance was 3.9 for axial and 3.8 for coronal images. HASTE DWI had a sensitivity/specificity of 81.8%/66.7% with the highest reliance of all evaluated sequences (4.4). Cases with a reliance level of 5 showed a sensitivity/specificity of 100% in all sequences. A reliance level of 5 was given in the axial and coronal RESOLVE DWI in 32.5% of cases and in the HASTE DWI in 57.5%.

CONCLUSION

The evaluated DWI sequences showed comparable results. The reliance level significantly improved the predictor of cholesteatoma disease with MRI techniques.

Radiological evaluation of the postsurgical middle ear

OBJECTIVE

The radiological evaluation of the postsurgical middle ear is complex due to the intricate anatomy of this region and the wide variety of procedures and materials used iin middle ear surgery. Knowledge of these factors will enable normal postsurgical changes to be differentiated from complications. This article describes the most common surgical procedures in the middle ear, their indications, and the normal radiological appearance after these procedures. It reviews the most common causes of failure in stapes surgery, in surgery for chronic otitis media, and in surgery for cholesteatoma, suggesting the best imaging method to assess the middle ear in each case.

CONCLUSION

Computed tomography enables the evaluation of prostheses and the aeration of the cavities, whereas magnetic resonance imaging makes it possible to characterize the possible occupation of the cavities and is the technique of choice for the follow-up of closed mastoidectomy for cholesteatomas.

Diffusion-Weighted Imaging of the Head and Neck (Including Temporal Bone)

Diffusion techniques provide valuable information when performing head and neck imaging. This information can be used to detect the presence or absence of pathology, refine differential diagnosis, determine the location for biopsy, assess response to treatment, and prognosticate outcomes. For example, when certain technical factors are taken into consideration, diffusion techniques prove indispensable in assessing for residual cholesteatoma following middle ear surgery. In other scenarios, pretreatment apparent diffusion coefficient values may assist in prognosticating outcomes in laryngeal cancer and likelihood of response to radiation therapy. As diffusion techniques continue to advance, so too will its clinical utility.

Advanced Magnetic Resonance Imaging of the Skull Base

Magnetic resonance (MR) imaging is a crucial tool for evaluation of the skull base, enabling characterization of complex anatomy by utilizing multiple image contrasts. Recent technical MR advances have greatly enhanced radiologists' capability to diagnose skull base pathology and help direct management. In this paper, we will summarize cutting-edge clinical and emerging research MR techniques for the skull base, including high-resolution, phase-contrast, diffusion, perfusion, vascular, zero echo-time, elastography, spectroscopy, chemical exchange saturation transfer, PET/MR, ultra-high-field, and 3D visualization. For each imaging technique, we provide a high-level summary of underlying technical principles accompanied by relevant literature review and clinical imaging examples.

Postoperative Imaging of the Temporal Bone

The anatomy of the temporal bone is complex, and postoperative imaging evaluation of this bone can be challenging. Surgical approaches to the temporal bone can be categorized didactically into tympanoplasty and ossicular reconstruction, mastoidectomy, and approaches to the cerebellopontine angle and internal auditory canal (IAC). In clinical practice, different approaches can be combined for greater surgical exposure. Postoperative imaging may be required for follow-up of neoplastic lesions and to evaluate unexpected outcomes or complications of surgery. CT is the preferred modality for assessing the continuity of the reconstructed conductive mechanism, from the tympanic membrane to the oval window, with use of grafts or prostheses. It is also used to evaluate aeration of the tympanic and mastoid surgical cavities, as well as the integrity of the labyrinth, ossicular chain, and tegmen. MRI is excellent for evaluation of soft tissue. Use of a contrast-enhanced fat-suppressed MRI sequence is optimal for follow-up after IAC procedures. Non-echo-planar diffusion-weighted imaging is optimal for detection of residual or recurrent cholesteatoma. The expected imaging findings and complications of the most commonly performed surgeries involving the temporal bone are summarized in this review. Online supplemental material is available for this article. ^©RSNA, 2021.

Non-EPI versus Multishot EPI DWI in Cholesteatoma Detection: Correlation with Operative Findings

BACKGROUND AND PURPOSE

Although multishot EPI (readout-segmented EPI) has been touted as a robust DWI sequence for cholesteatoma evaluation, its efficacy in disease detection compared with a non-EPI (eg, HASTE) technique is unknown. This study sought to compare the accuracy of readout-segmented EPI with that of HASTE DWI in cholesteatoma detection.

MATERIALS AND METHODS

A retrospective review was completed of consecutive patients who underwent MR imaging for the evaluation of suspected primary or recurrent/residual cholesteatomas. Included patients had MR imaging examinations that included both HASTE and readout-segmented EPI sequences and confirmed cholesteatomas on a subsequent operation. Two neuroradiologist reviewers assessed all images, with discrepancies resolved by consensus. The ratio of signal intensity between the cerebellum and any observed lesion was noted.

RESULTS

Of 23 included patients, 12 (52.2%) were women (average age, 47.8 [SD, 25.2] years). All patients had surgically confirmed cholesteatomas: Six (26.1%) were primary and 17 (73.9%) were recidivistic. HASTE images correctly identified cholesteatomas in 100.0% of patients. On readout-segmented EPI sequences, 16 (69.6%) were positive, 5 (21.7%) were equivocal, and 2 (8.7%) were falsely negative. Excellent interobserver agreement was noted between reviews on both HASTE (κ = 1.0) and readout-segmented EPI (κ = 0.9) sequences. The average signal intensity ratio was significantly higher on HASTE than in readout-segmented EPI, facilitating enhanced detection (mean difference 0.5; 95% CI, 0.3-0.8; P = .003).

CONCLUSIONS

HASTE outperforms readout-segmented EPI in the detection of primary cholesteatoma and disease recidivism.

Distribution of different morphological types of anterior epitympanic plate “cog” and Köerner’s septum in CT images of cholesteatomatous and non-cholesteatomatous CSOM: is it really significant?

Background

The anterior epitympanic plate (cog) and Köerner’s septum are gaining more importance since the introduction of transcanal mastoidectomy as these anatomical structures are serving landmarks for the attic. Moreover, different morphological types of cog and Köerner’s septum revealed embryological relation to the development of the isthmic membrane; the latter is linked to aeration of the attic and thus affects the pathological development of the cholesteatoma.

Results

A retrospective review of CT images of 86 patients proved by surgical biopsies revealed: 49 cholesteatomas and 37 non-cholesteatomatous CSOM. The type-I “cog” had a higher incidence (n = 40) and was statistically more prevalent in non-cholesteatomatous CSOM (n = 30, 81.1%). Type-II was the second commonest and was statistically more prevalent in cholesteatomatous CSOM (n = 22, 44.9%). Type-III was the third commonest, seen in (n = 18, 20.9%) and was statistically more prevalent in cholesteatomatous CSOM (n = 17, 34.7%). Köerner’s septum was more prevalent in non-cholesteatomatous CSOM (70.3%) with statistical significance (p value = 0.002).

Conclusions

The difference in the distribution of different morphological types of anterior epitympanic plate “cog,” as well as the difference in Köerner’s septum existence amongst cholesteatomatous and non-cholesteatomatous CSOM are suggested as risk factors for the development of cholesteatoma and may predict a cholesteatoma on CT images.

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.

Diagnostic benefit of high b-value computed diffusion-weighted imaging in acute brainstem infarction

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) is a cornerstone in diagnostic of ischemic stroke. The aim of this study was to investigate the usefulness of high-b-value computed DWI (c-DWI) in comparison to standard DWI in patients with acute brainstem infarction.

MATERIALS AND METHODS

56 patients with acute brainstem infarction were retrospectively analysed by two readers. DWI was obtained with the b-values 0, 500 and 1000 s/mm² on either a 1.5 or 3 T magnetic resonance imaging (MRI) scanner. c-DWI was calculated with a monoexponential model with high b-values 2000, 3000, 4000 and 5000 s/mm². All c-DWI series with high-b-values were compared to the standard DWI sequence at b-value of 1000 s/mm² in terms of image artifacts, lesion extent and contrast.

RESULTS

There was no statistically significant difference between 1.5 and 3 T MRI regarding the measured ischemic lesion size. There were no statistically significant differences between the ischemic lesion sizes on DWI at b-values of 1000 s/mm² and on c-DWI at higher b-values. Overall, the contrast between the lesion and the surrounding normal areas improved with increasing b-value on the isotropic DWIs: maximum at b = 5000, followed by that at b 2000 and b 1000 s/mm², in order. The best relation between artifacts and lesion contrast was identified for b 2000 s/mm².

CONCLUSION

High b-value DWI derived from c-DWI has a higher visibility for ischemic brainstem lesions compared to standard DWI without additional time cost. The b-2000 image is recommended to use in clinical routine, higher b-value images lead to more imaging artifacts, which might result in misdiagnosis.

Rapid golden-angle diffusion-weighted propeller MRI for simultaneous assessment of ADC and IVIM

Purpose:

Golden-angle single-shot PROPLLER (GA-SS-PROP) is proposed to accelerate the PROPELLER acquisition for distortion-free diffusion-weighted (DW) imaging. Acceleration is achieved by acquiring one-shot per b-value and several b-values can be acquired along a diffusion direction, where the DW signal follows a bi-exponential decay (i.e. IVIM). Sparse reconstruction is used to reconstruct full resolution DW images. Consequently, apparent diffusion coefficient (ADC) map and IVIM maps (i.e., perfusion fraction (f) and the perfusion-free diffusion coefficient (D)) are obtained simultaneously. The performance of GA-SS-PROP was demonstrated with simulation and human experiments.

Methods:

A realistic numerical phantom of high-quality diffusion images of the brain was developed. The error of the reconstructed DW images and quantitative maps were compared to the ground truth. The pulse sequence was developed to acquire human brain data. For comparison, fully sampled PROPELLER and conventional single-shot echo planar imaging (SS-EPI) acquisitions were performed.

Results:

GA-SS-PROP was 5 times faster than conventional PROPELLER acquisition with comparable image quality. The simulation demonstrated that sparse reconstruction is effective in restoring contrast and resolution. The human experiments demonstrated that GA-SS-PROP achieved superior image fidelity compared to SS-EPI for the same acquisition time and same in-plane resolution (1 × 1 mm²).

Conclusion:

GA-SS-PROP offers fast, high-resolution and distortion-free DW images. The generated quantitative maps (f, D and ADC) can provide valuable information on tissue perfusion and diffusion properties simultaneously, which are desirable in many applications, especially in oncology. As a turbo spin-echo based technique, it can be applied in most challenging regions where SS-EPI is problematic.

Technical Improvements in Head and Neck MR Imaging: At the Cutting Edge

Head and neck MR imaging is technically challenging because of magnetic field inhomogeneity, respiratory and swallowing motion, and necessity of high-resolution imaging to trace key anatomic structures. These challenges have been answered by advances in MR imaging technology, including isovolumetric three-dimensional imaging, robust fat-water separation techniques, and novel deep learning-based reconstruction algorithms. New applications of MR imaging have been advanced and functional imaging has been improved. Improvements in acquisition and reconstruction technique facilitate novel applications of morphologic and functional imaging. This results in opportunities to improve diagnosis, staging, and treatment selection through application of advanced MR imaging techniques.

Negative Predictive Value of Non-Echo-Planar Diffusion Weighted MR Imaging for the Detection of Residual Cholesteatoma Done at 9 Months After Primary Surgery Is not High Enough to Omit Second Look Surgery

OBJECTIVES

To evaluate non echo-planar diffusion weighted magnetic resonance imaging (non-EP DW MRI) at 9 months after primary surgery to rule out residual cholesteatoma in patients scheduled before second-look-surgical exploration.

STUDY DESIGN

Prospective observational study.

SETTING

Secondary teaching hospital.

PATIENTS/INTERVENTIONS

Patients who were scheduled for second-look-surgery after primary canal wall up repair of cholesteatoma underwent 1.5 T MRI including non-EP DWI and high-resolution coronal T1 and T2-FS SE sequences.

MAIN OUTCOME MEASURES

Imaging studies were evaluated for the presence of cholesteatoma by three independent observers. Intraoperative observations were regarded the standard of reference. Ear, nose, throat (ENT) surgeons were blinded for imaging findings. The primary outcome was the negative predictive value (NPV) of MR imaging, secondary outcomes were sensitivity, specificity, and positive predictive value.

RESULTS

Thirty-three patients underwent both MRI and surgery, among whom 22 had a cholesteatoma. Mean time between primary surgery and MRI was 259 days (standard deviation [SD] 108). NPV of non-EP DW MRI in detecting recurrent cholesteatoma was 53% (95% CI: 32-73%). Sensitivity and specificity were 59% (39-77%) and 91% (62-98%), respectively. The positive predictive value was 93% (69-99%). In five out of nine false-negative cases, recurrent cholesteatoma measured 3 mm or less. Using a 3 mm detection threshold, NPV increased to 79%.

CONCLUSION

Non-EP DW MRI cannot replace second look surgery in ruling-out residual cholesteatoma at 9 months after primary surgery. It could be used in a follow-up strategy in low risk patients. Further research is needed which types of residual cholesteatoma are not revealed by MRI.

Apparent diffusion coefficients for predicting primary cholesteatoma risk of recurrence after surgical clearance

PURPOSE

Beside the well-known accuracy of non-EPI DWI techniques and relative ADC maps in detecting cholesteatomatous tissue, ADC can also represent a useful tool for stratifying cholesteatoma risk of recurrence. Aim of this study is to test the role of ADC in determining risk of recurrence for primary middle ear cholesteatoma, proposing stratification based on pre-operative mean (mADC) and normalized (nADC) ADC values.

METHODS

In this prospective study, 60 patients with primary unilateral middle ear cholesteatoma underwent a three-years-long follow-up to assess the presence of recurrent disease after macroscopically complete excisional surgery. Baseline MRI examination mADC and nADC values in the group with early evidence of recurrent cholesteatoma were compared to the group with no evidence of recurrence by using T statistics.

RESULTS

ADC values on pre-operative MRI examination were lower in cholesteatomas with early evidence of recurrence, and statistical significance was slightly higher for nADC compared to mADC measurements. We also determined a cut-off between the two groups, proposing stratification in high-risk of recurrence cholesteatomas (mADC≤ 1000 or nADC< 1.3) and low-risk cholesteatomas (mADC>1000 or nADC≥1.3).

CONCLUSIONS

ADC values resulted discriminating in identifying cholesteatomas with higher risk of early recurrence, both for mean and normalized ADC, with optimized tissue characterization and outcome prediction.

Recent advances in MRI of the head and neck, skull base and cranial nerves: new and evolving sequences, analyses and clinical applications

MRI is an invaluable diagnostic tool in the investigation and management of patients with pathology of the head and neck. However, numerous technical challenges exist, owing to a combination of fine anatomical detail, complex geometry (that is subject to frequent motion) and susceptibility effects from both endogenous structures and exogenous implants. Over recent years, there have been rapid developments in several aspects of head and neck imaging including higher resolution, isotropic 3D sequences, diffusion-weighted and diffusion-tensor imaging as well as permeability and perfusion imaging. These have led to improvements in anatomic, dynamic and functional imaging. Further developments using contrast-enhanced 3D FLAIR for the delineation of endolymphatic structures and black bone imaging for osseous structures are opening new diagnostic avenues. Furthermore, technical advances in compressed sensing and metal artefact reduction have the capacity to improve imaging speed and quality, respectively. This review explores novel and evolving MRI sequences that can be employed to evaluate diseases of the head and neck, including the skull base.

Cost-comparison analysis of diffusion weighted magnetic resonance imaging (DWMRI) versus second look surgery for the detection of residual and recurrent cholesteatoma

Background

Cholesteatoma is a destructive, erosive growth of keratinizing squamous epithelium in the middle ear cleft. Following treatment with a canal wall-up (CWU) tympanomastoidectomy, surveillance of residual and recurrent disease has traditionally been achieved through a second look tympanotomy following the initial procedure. Historically, MRI sequences have been inadequate at differentiating between granulation tissue, inflammation, and cholesteatoma. Recent literature has shown diffusion-weighted magnetic resonance imaging (DWMRI) to be a viable alternative to second look surgery for the detection of residual or recurrent disease. The goal of the present study was to perform a cost analysis of DWIMRI versus second look surgery in the detection of residual or recurrent cholesteatoma following combined approach tympanomastoidectomy.

Methods

A probabilistic decision tree model was generated from a literature review to compare traditional second look surgery with DWMRI. Cost inputs were obtained from the Ontario Case Costing Initiative, the Ontario Health Insurance Plan (OHIP) schedule of benefits. Costs were reported in Canadian dollars and a payer perspective was adopted. A probabilistic sensitivity analysis was performed.

Results

According to the probabilistic sensitivity analysis, mean cost difference of traditional second look tympanotomy versus echo planar imaging (EPI) DWMRI was $180.27CAD, 95%CI [$177.32, $188,32] in favour of second-look tympanotomy. However, mean cost difference of traditional second look tympanotomy versus non-EPI DWMRI was $390.66CAD, 95%CI [$381.52, $399.80] in favour of non-EPI DWMRI.

Conclusions

Diffusion-weighted MRI, specifically non-EPI sequences, are a viable cost-saving alternative to second-look tympanotomy in the setting of detecting residual or recurrent cholesteatoma.

Readout-Segmented Echo-Planar DWI for the Detection of Cholesteatomas: Correlation with Surgical Validation

BACKGROUND AND PURPOSE

MR imaging has become an important tool for the detection of cholesteatomas of the middle ear. Various diffusion-weighted imaging sequences are available and have shown promising results. This study aimed to evaluate readout-segmented echo-planar DWI for the detection of cholesteatoma and compare the results with surgical validation.

MATERIALS AND METHODS

Fifty patients with chronic otitis media (24 females and 26 males; range, 12-76 years of age; mean age, 41 years) who underwent MR imaging before an operation of the middle ear (1-169 days) were included. The MR imaging protocol consisted of axial and coronal readout-segmented echo-planar DWI with b-values of 0 and 1000 s/mm² and 3-mm slice thickness. The readout-segmented echo-planar diffusion-weighted images were fused with standard T2-weighted sequences for better anatomic assignment. The results of the MR imaging evaluation were correlated with the results from the operation.

RESULTS

Readout-segmented echo-planar DWI detected 22 of the 25 cases of surgically proved cholesteatoma. It has an accuracy of 92% (95% confidence interval, 80.8%-97.8%), a sensitivity of 88%, a specificity of 96%, a positive predictive value of 96%, and a negative predictive value of 89%. In 1 case, a positive finding for cholesteatoma with readout-segmented echo-planar DWI could not be proved by histology, and in 3 cases, histology yielded a cholesteatoma that was not detected with MR imaging.

CONCLUSIONS

Readout-segmented echo-planar DWI is a promising and reliable MR imaging sequence for the detection and exclusion of cholesteatoma.

The quest for high spatial resolution diffusion-weighted imaging of the human brain in vivo

Diffusion-weighted imaging, a contrast unique to MRI, is used for assessment of tissue microstructure in vivo. However, this exquisite sensitivity to finer scales far above imaging resolution comes at the cost of vulnerability to errors caused by sources of motion other than diffusion motion. Addressing the issue of motion has traditionally limited diffusion-weighted imaging to a few acquisition techniques and, as a consequence, to poorer spatial resolution than other MRI applications. Advances in MRI imaging methodology have allowed diffusion-weighted MRI to push to ever higher spatial resolution. In this review we focus on the pulse sequences and associated techniques under development that have pushed the limits of image quality and spatial resolution in diffusion-weighted MRI.

Quantitative diffusion magnetic resonance imaging in head and neck tumors

In patients with head and neck cancer, conventional anatomical magnetic resonance imaging (MRI) scans are commonly used for identification of primary lesion, assessment of structural distortion, and presence of metastatic lymph nodes. However, quantitative analysis of diffusion MRI can provide added value to structural and anatomical evaluation of head and neck tumors (HNT), by differentiation of primary malignant process, prognostic prediction, and treatment monitoring. In this article, we will review the applications of quantitative diffusion MRI in identification of primary malignant tissue, differentiation of tumor pathology, prediction of molecular phenotype, monitoring of treatment response, and evaluation of posttreatment changes in patient with HNT.

Cholesteatoma Pearls: Practical Points and Update

The European Academy of Otology and Neurotology in collaboration with the Japanese Otological Society (EAONO/JOS) recently produced a joint consensus document outlining the definitions, classification and staging of middle ear cholesteatoma. The goals were to provide terminologies in the description of cholesteatoma, classify cholesteatoma into distinct categories to facilitate the comparison of surgical outcomes and to provide a staging system that reflects the severity, difficulty of complete removal and restoration of normal function. Cholesteatoma is considered a benign, expanding and destructive epithelial lesion of the temporal bone that is the result of a multifactorial process. If undetected and left treated, cholesteatoma may lead to significant complications including hearing loss, temporal bone destruction and cranial invasion. Recent advances in imaging modalities have allowed for high sensitivity and specificity in identifying the presence of cholesteatoma. Despite these advances, deficiencies exist around the world with access to health care facilities meaning cholesteatoma remains a serious and challenging entity to manage whether found within the pediatric or adult population. Proper diagnosis and management of each form of cholesteatoma is achieved by a thorough understanding of the etiology, classification, clinical presentation and histology, thereby facilitating prevention, early detection and appropriate treatment.

ADC Benchmark Range for Correct Diagnosis of Primary and Recurrent Middle Ear Cholesteatoma

OBJECTIVES

Magnetic resonance imaging (MRI) and in particular diffusion-weighted imaging (DWI) have been broadly proven to be the reference imaging method to discriminate between cholesteatoma and noncholesteatomatous middle ear lesions, especially when high tissue specificity is required. The aim of this study is to define a range of apparent diffusion coefficient (ADC) values within which the diagnosis of cholesteatoma is almost certain.

METHODS

The study was retrospectively conducted on a cohort of 124 patients. All patients underwent first- or second-look surgery because primary or secondary acquired cholesteatoma was clinically suspected; they all had preoperative MRI examination 15 days before surgery, including DWI from which the ADC maps were calculated.

RESULTS

Average ADC value for cholesteatomas was 859,4 × 10-6 mm2/s (range 1545 × 10-6 mm2/s; IQR = 362 × 10-6 mm2/s; σ = 276,3 × 10-6 mm2/s), while for noncholesteatomatous inflammatory lesions, it was 2216,3 × 10-6 mm2/s (range 1015 × 10-6 mm2/s; IQR = 372,75 × 10-6 mm2/s; σ = 225,6 × 10-6 mm2/s). Interobserver agreement with Fleiss' Kappa statistics was 0,96. No overlap between two groups' range of values was found and the difference was statistically significant for p < 0.0001.

CONCLUSIONS

We propose an interval of ADC values that should represent an appropriate benchmark range for a correct differentiation between cholesteatoma and granulation tissue or fibrosis of noncholesteatomatous inflammatory lesions.

Comparison of DWI Methods in the Pediatric Brain: PROPELLER Turbo Spin-Echo Imaging Versus Readout-Segmented Echo-Planar Imaging Versus Single-Shot Echo-Planar Imaging

OBJECTIVE

The purpose of this study is to compare DWI for pediatric brain evaluation using single-shot echo-planar imaging (EPI), periodically rotated overlapping parallel lines with enhanced reconstruction (Blade), and readout-segmented EPI (Resolve).

MATERIALS AND METHODS

Blade, Resolve, and single-shot EPI were performed for 27 pediatric patients (median age, 9 years), and three datasets were independently reviewed by two radiologists. Qualitative analyses were performed for perceptive coarseness, image distortion, susceptibility-related changes, motion artifacts, and lesion conspicuity using a 5-point Likert scale. Quantitative analyses were conducted for spatial distortion and signal uniformity of each sequence.

RESULTS

Mean scores were 2.13, 3.17, and 3.76 for perceptive coarseness; 4.85, 3.96, and 2.19 for image distortion; 4.76, 3.96, and 2.30 for susceptibility-related change; 4.96, 3.83, and 4.69 for motion artifacts; and 2.71, 3.75, and 1.92 for lesion conspicuity, for Blade, Resolve, and single-shot EPI, respectively. Blade and Resolve showed better quality than did single-shot EPI for image distortion, susceptibility-related changes, and lesion conspicuity. Blade showed less image distortion, fewer susceptibility-related changes, and fewer motion artifacts than did Resolve, whereas lesion conspicuity was better with Resolve. Blade showed increased signal variation compared with Resolve and single-shot EPI (coefficients of variation were 0.10, 0.08, and 0.05 for lateral ventricle; 0.13, 0.09, and 0.05 for centrum semiovale; and 0.16, 0.09, and 0.06 for pons in Blade, Resolve, and single-shot EPI, respectively).

CONCLUSION

DWI with Resolve or Blade yields better quality regarding distortion, susceptibility-related changes, and lesion conspicuity, compared with single-shot EPI. Blade is less susceptible to motion artifacts than is Resolve, whereas Resolve yields less noise and better lesion conspicuity than does Blade.

Accuracy of turbo spin-echo diffusion-weighted imaging signal intensity measurements for the diagnosis of cholesteatoma

PURPOSE

We aimed to evaluate the diagnostic accuracy of turbo spin-echo diffusion-weighted imaging (TSE-DWI) at 3 T, for cholesteatoma (CS) diagnosis, using qualitative and quantitative methods with numerical assessment of signal intensity (SI), signal intensity ratios (SIR), and apparent diffusion coefficient (ADC) values.

METHODS

In this retrospective study, two blinded observers independently evaluated the preoperative TSE-DWI images of 57 patients who were imaged with a presumed diagnosis of CS. Qualitative assessment with respect to the SI of the adjacent cortex and quantitative measurements of SI, SIR, and ADC values were performed.

RESULTS

Surgery with histopathologic examination revealed 30 CS patients and 27 patients with non-cholesteatoma (NCS) lesions including chronic inflammation and cholesterol granuloma. On TSE-DWI, 96.7% of the CS lesions and none of the NCS lesions appeared hyperintense compared with the cortex. The mean SI and SIR indices of the CS group were significantly higher and the mean ADC values significantly lower compared with those of the NCS group (P < 0.001). Using specific cutoff values for SI (92.5) and SIR (0.9), CS could be diagnosed with 100% sensitivity and specificity. The use of quantitative imaging further increased the sensitivity of the TSE-DWI technique.

CONCLUSION

The quantitative indices of SI, SIR, and ADC of TSE-DWI appear to be highly accurate parameters that can be used to confirm the diagnosis of CS.

Technical Note: Diffusion-weighted MRI with minimal distortion in head-and-neck radiotherapy using a turbo spin echo acquisition method

PURPOSE

Diffusion-weighted (DW) MRI, showing high contrast between tumor and background tissue, is a promising technique in radiotherapy for tumor delineation. However, its use for head-and-neck patients is hampered by poor geometric accuracy in conventional echo planar imaging (EPI) DW-MRI. An alternative turbo spin echo sequence, DW-SPLICE, is implemented and demonstrated in patients.

METHODS

The DW-SPLICE sequence was implemented on a 3.0 T system and evaluated in 10 patients. The patients were scanned in treatment position, using a customized head support and immobilization mask. Image distortions were quantified at the gross tumor volume (GTV) using field map analysis. The apparent diffusion coefficient (ADC) was evaluated using an ice water phantom.

RESULTS

The DW images acquired by DW-SPLICE showed no image distortions. Field map analysis at the gross tumor volumes resulted in a median distortion of 0.2 mm for DW-SPLICE, whereas for the conventional method this was 7.2 mm. ADC values, measured using an ice water phantom were in accordance with literature values.

CONCLUSIONS

The implementation of DW-SPLICE allows for diffusion-weighted imaging of patients in treatment position with excellent geometrical accuracy. The images can be used to facilitate target volume delineation in RT treatment planning.

Diffusion weighted imaging for the detection and evaluation of cholesteatoma

Cholesteatoma is a collection of keratinous debris and stratified squamous epithelium. It is trapped in the middle ear and can lead to bony erosion. The disease is treated surgically often followed by a second-look procedure to check for residual tissue or recurrence. Cholesteatoma has specific signal-intensity characteristics on magnetic resonance imaging with very high signal intensity on diffusion weighted imaging (DWI). Various DWI techniques exist: Echo-planar imaging (EPI)-based and non-EPI-based techniques as well as new approaches like multi-shot EPI DWI. This article summarizes all techniques, discusses the significance in detecting cholesteatoma and mentions actual studies. Further recommendations for daily clinical practise are provided.

The accuracy and sensitivity of diffusion-weighted magnetic resonance imaging with Apparent Diffusion Coefficients in diagnosis of recurrent cholesteatoma

OBJECTIVE

To evaluate the accuracy and sensitivity of diffusion-weighted magnetic resonance imaging with ADC value combined with MDCT in evaluating recurrent cholesteatoma.

PATIENTS

Thirty patients (20 females and 10 males), their age ranged from 10 to 40years, had undergone a tympanomastoid surgery for a cholesteatoma of the middle ear underwent MDCT and MR DWI examination before second- or third-look surgery from May 2015 to October 2016.

RESULTS

CT showed partial opacification of the tympanomastoid cavity in 10 ears and complete opacification in 21 ears. CT detects 10 cases out of 20 cases of recurrent cholesteatoma with sensitivity 47.6%, specificity 100%, and NPP 47.6%. DWI depicted 21 out of 20 cases proved cholesteatoma patients (sensitivity 100%, specificity 90%, PPV 95.2% and P value is 0.001). All MRI of patients without cholesteatoma were correctly interpreted as showing negative findings for cholesteatoma (specificity = 100%). The ADC of cholesteatoma group (21 ears) were ranged from 553 to 759 × 10-3 mm2/s and the ADCs of non cholesteatoma group (10 ears) was ranged from 1495.8 to 1766.8 × 10-3 mm2/s. Cut off value of cholesteatoma is ≤759 × 10-3 mm2/s.

CONCLUSION

MR DWI with ADC combined with MDCT has high sensitivity, specificity, accuracy in detecting recurrent cholesteatoma.

Diffusion-Weighted Magnetic Resonance Imaging of Cholesteatoma Using PROPELLER at 1.5T: A Single-Centre Retrospective Study

PURPOSE

The purpose of this study was to evaluate the sensitivity, specificity, and positive and negative predictive values of the diffusion-weighted periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique in the detection of cholesteatoma at our institution with surgical confirmation in all cases.

METHODS

A retrospective review of 21 consecutive patients who underwent diffusion-weighted PROPELLER magnetic resonance imaging (MRI) on a 1.5T MRI scanner prior to primary or revision/second-look surgery for suspected cholesteatoma from 2009-2012 was performed.

RESULTS

Diffusion-weighted PROPELLER had a sensitivity of 75%, specificity of 60%, positive predictive value of 86%, and negative predictive value of 43%. In the 15 patients for whom the presence or absence of cholesteatoma was correctly predicted, there were 2 cases where the reported locations of diffusion restriction did not correspond to the location of the cholesteatoma observed at surgery.

CONCLUSION

On the basis of our retrospective study, we conclude that diffusion-weighted PROPELLER MRI is not sufficiently accurate to replace second look surgery at our institution.

Non-echoplanar diffusion weighted imaging in the detection of post-operative middle ear cholesteatoma: navigating beyond the pitfalls to find the pearl

Abstract

Non-echoplanar diffusion weighted magnetic resonance imaging (DWI) has established itself as the modality of choice in detecting and localising post-operative middle ear cleft cholesteatoma. Despite its good diagnostic performance, there are recognised pitfalls in its radiological interpretation which both the radiologist and otologist should be aware of. Our article highlights the various pitfalls and provides guidance for improving radiological interpretation and navigating beyond many of the pitfalls. It is recommended radiological practice to interpret the diffusion weighted images together with the ADC map and supplement with the corresponding T1 weighted and T2 weighted images, all of which can contribute to and enhance lesion localisation and characterisation. ADC values are also helpful in improving specificity and confidence levels. Given the limitation in sensitivity in detecting small cholesteatoma less than 3 mm, serial monitoring with DWI over time is recommended to allow any small residual cholesteatoma pearls to grow and become large enough to be detected on DWI. Optimising image acquisition and discussing at a joint clinico-radiological meeting both foster good radiological interpretation to navigate beyond the pitfalls and ultimately good patient care.

Teaching Points

• Non-echoplanar DWI is the imaging of choice in detecting post-operative cholesteatoma.

• There are recognised pitfalls which may hinder accurate radiological interpretation.

• Interpret with the ADC map /values and T1W and T2W images.

• Serial DWI monitoring is of value in detection and characterisation.

• Optimising image acquisition and discussing at clinico-radiological meetings enhance radiological interpretation.

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

OBJECTIVE

To assess the efficacy of a color-mapped diffusion-weighted image combined with a computed tomography scan (CMDWI-CT) in preoperatively evaluating the anatomical location of cholesteatomas and determining whether a patient is indicated for transcanal endoscopic ear surgery (TEES) to reduce intraoperative switching to microscopic ear surgery (MES).

STUDY DESIGN

Prospective case study.

SETTING

A single university hospital.

PATIENTS

Fifty-five patients scheduled for middle ear cholesteatoma surgery.

INTERVENTION

The CMDWI-CT is produced in a multistep process. A color-mapped fusion image (CMFI) is created by performing MR cisternography on a 1-mm thin-slice nonecho planar diffusion-weighted imaging (non-EPI DWI) and then by performing color mapping on the resulting image to enhance cholesteatoma visualization. False positives are reduced by taking a T1-weighted image (T1WI), whereas false negatives are further reduced by preoperative endoscopic examination. As cholesteatomas are difficult to locate on a CMFI in the temporal bone region, we stripped out the MR cisternography data from the CMFI and then fused the CMFI to the initial computer tomography (CT) scan to create a CMDWI-CT. This CMDWI-CT better clarifies the cholesteatoma position within temporal bone.

MAIN OUTCOME MEASURE(S)

CMDWI-CT preoperative findings were compared with intraoperative findings. The positive predictive value and negative predictive value were also evaluated depending on the cholesteatoma location.

RESULTS

CMDWI-CT facilitated accurate detection of the cholesteatoma anatomical location in the temporal bone region which was reflected in positive predictive and negative predictive values of over 90% for all areas of the middle ear.

CONCLUSION

CMDWI-CT is a reliable diagnostic modality for evaluating the anatomical location of cholesteatomas that seem as high-signal regions on a CMFI and for determining whether TEES is indicated for treatment in such patients.

Imaging innovations in temporal bone disorders

The development of new imaging techniques coupled with new treatment algorithms has created new possibilities in treating temporal bone diseases. This article provides an overview of recent imaging innovations that can be applied to temporal bone diseases. Topics covered include the role of magnetic resonance (MR) diffusion-weighted imaging in cholesteatomas and skull base epidermoids, whole-body molecular imaging in paragangliomas of the jugular foramen, and MR arterial spin labeling perfusion for dural arteriovenous fistulas and arteriovenous malformations.

Radiology of external ear: indications, normal anatomy, and pathological processes

The external ear is accessible to direct examination; the clinical history and otoscopy are sufficient to diagnose and treat most diseases of the external ear. We aim to describe the normal anatomy of the external ear, specify the indications for imaging tests, and review the clinical and radiological manifestations of the most common diseases affecting the external ear. We classify these diseases according to their origin into congenital, inflammatory, infectious, or traumatic disease or benign bone tumors or malignant tumors. Imaging does not play an important role in diseases of the external ear, but in certain clinical scenarios it can be crucial for reaching a concrete diagnosis and establishing the best treatment. Computed tomography is the first-choice technique for most diseases. Magnetic resonance imaging complements computed tomography and makes it possible to differentiate among different tissue types and to evaluate the extension of disease accurately.

Evaluation of cholesteatoma: our experience with DW Propeller imaging

BACKGROUND

Cholesteatoma management includes early detection and surgical exploration. Due to its tendency to recur, it can be potentially locally aggressive. Magnetic resonance imaging (MRI), and in particular diffusion weighted imaging (DWI), plays an important role in management of these lesions.

PURPOSE

To assess the accuracy of Propeller (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) DW sequence in detecting middle ear and mastoid cholesteatomas in non-operated ears by surgical correlation.

MATERIAL AND METHODS

A retrospective review of 15 patients was done who underwent Propeller DWI with either clinically confirmed or suspected cholesteatomas. Surgical correlation was done in all cases.

RESULTS

All patients had hyperintense foci on Propeller DWI. Surgical correlation performed revealed that 13 patients had cholesteatomas while two patients had mastoid abscesses. The location, extent, and size of cholesteatomas on Propeller DWI matched with the operative findings. Of the 13 patients with cholesteatomas, three patients had multiple foci of hyperintensity on Propeller DWI, which corroborated with the surgical finding of multiple cholesteatomas. The average apparent diffusion coefficient value of cholesteatoma was 0.868 × 10(-3) mm(2)/s, found to be higher than that of abscess, which was 0.425 × 10(-3) mm(2)/s.

CONCLUSION

Propeller DWI was accurate in assessing the location, extent, and size of cholesteatomas as corroborated with surgical findings. Propeller DWI is useful in detecting number of cholesteatoma foci, a vital finding as it may impact the choice of surgery.

Non-echoplanar diffusion-weighted MRI in children and adolescents with cholesteatoma: reliability and pitfalls in comparison to middle ear surgery

BACKGROUND

Currently, there is only limited and contradictory evidence of the role of diffusion-weighted MRI (DW-MRI) in the management of children with cholesteatoma.

OBJECTIVE

To provide surgically controlled data that may allow to replace second-look surgery by non-echoplanar DW-MRI in children.

MATERIALS AND METHODS

Fifty-five children and adolescents with a median age of 8.6 years (2.2-17.7 years) underwent 61 preoperative half-Fourier acquisition single-shot turbo spin-echo (HASTE) DW-MRI of their petrous bone. Surgical interventions followed within 24 h (79%), within 5 months (20%) or at 18 months (1 case).

RESULTS

Surgery detected a cholesteatoma or retraction pocket in 41 of 61 cases (67%). In 49 cases (80%), the MR result was confirmed by surgical findings. Two MR findings were false-positive and 10 false-negative (including cholesteatomas <4 mm). HASTE DW-MRI alone had a sensitivity of 76% and a specificity of 90%. The positive predictive value was 94%, the negative predictive value 64%. In combination with preoperative otoscopy, sensitivity was 90% and negative predictive value 82%.

CONCLUSION

DW-MRI correctly detected the majority of lesions but could not reliably exclude small cholesteatomas and empty retraction pockets. We would therefore not generally recommend MR as a substitute for second-look surgery.