Repeated Postoperative Follow-up Diffusion-weighted Magnetic Resonance Imaging to Detect Residual or Recurrent Cholesteatoma

Early non-EPI DW-MRI after cholesteatoma surgery

OBJECTIVE

Middle ear cholesteatoma may lead to the erosion of the bony structures of the temporal bone, possibly causing intra- and extracranial complications. Surgical treatment is mandatory, and due to possible residual/recurrent disease, the use of reliable diagnostic methods is essential. Our study aimed to evaluate the reliability of non-EPI DW-MRI for the follow-up of cholesteatoma after surgery.

METHODS

In a study group including 53 consecutive patients who underwent surgery for cholesteatoma at a tertiary university hospital, an imaging protocol was applied, including non-echo planar diffusion-weighted imaging magnetic resonance (MR) at 1 month after surgery and then at 6 and 12 months after surgery. Based on the combination of preoperative assessment and intraoperative findings, the study group was divided into 3 subgroups: petrous bone (PB) cholesteatoma, complicated cholesteatoma and uncomplicated cholesteatoma. PB cholesteatoma patients were treated by a subtotal petrosectomy, whereas complicated and uncomplicated cholesteatoma patients were treated either by a canal wall up procedure or a retrograde (inside-out) canal wall down technique with bone obliteration technique (BOT).

RESULTS

The results show that patients who had positive findings on non-EPI DW-MRI scans 1 month after surgery consequently underwent revision surgery during which residual cholesteatoma was noted. All the patients who displayed negative findings on non-EPI DWI-MRI scan at 1 month after surgery did not show the presence of a lesion at the 6- and 12-month evaluations. The 6 patients who displayed residual cholesteatoma at the 1-month follow-up presented dehiscence/exposure of the facial nerve canal at the primary surgery, mostly at the level of the labyrinthine segment.

CONCLUSION

Non-EPI DW-MRI is a useful and reliable tool for follow-up cholesteatoma surgery, and when applied early, as was done in the protocol proposed in the present study, this tool may be used to detect the presence of residual cholesteatoma in some patients, prompting the planning of early revision surgery.

Evaluation of magnetic resonance imaging to detect cholesteatoma in clinical healthcare

BACKGROUND

Non-Echo-Planar Diffusion Weighed Magnetic Resonance Imaging (non-EPI DW MRI) plays a role in the planning of cholesteatoma surgery.

OBJECTIVES

To outline the usage of Non-EPI DW MRI in cholesteatoma diagnostics and to determine its accuracy, using otosurgery diagnostics as reference standard.

MATERIAL AND METHODS

A retrospective descriptive study. All subjects operated, with suspicion of cholesteatoma as indication, that had a preceding examination with non-EPI DW MRI, between October 2010 and March 2019. Calculating sensitivity, specificity, predicative values, and likelihood ratios, using non-EPI DW MRI as index test and diagnosis from otosurgery as reference standard.

RESULTS

Fifty-two subject episodes were included. Non-EPI DW MRI had a sensitivity of 0.50, specificity of 0.75, positive and negative predictive values of 0.74 and 0.52 and, positive and negative likelihood ratios of 2.0 and 0.67 respectively.

CONCLUSIONS AND SIGNIFICANCE

There is a clear annual trend with increased numbers of executed examinations during the study period. The diagnostic accuracy of non-EPI DW MRI does not reach acceptable levels in the existing everyday routine practice conditions. The accuracy of the examination increases when interpreted by an experienced radiologist and when using the definition of cholesteatoma recommended by EAONO/JOS.

Cost-Effectiveness of Diffusion-Weighted Magnetic Resonance Imaging Versus Second-Look Surgery in Treating Cholesteatoma: A Modeling Study

OBJECTIVE

To evaluate whether canal wall-up (CWU) tympanomastoidectomy with diffusion-weighted magnetic resonance imaging (DW-MRI) is a cost-effective method of treating cholesteatoma compared with CWU with second-look surgery.

DESIGN AND SETTING

Cost-effectiveness analysis was conducted using a Markov state transition model. The simulation model adhered to the Panel Recommendations on Cost-Effectiveness in Health and Medicine established by the US Public Health Service. One-way and Monte Carlo probability sensitivity analyses were conducted for validation.

INTERVENTIONS

Tympanomastoidectomy with DW-MRI versus tympanomastoidectomy with second-look surgery.

MAIN OUTCOME MEASURES

Effectiveness and health utility were measured using quality-adjusted life years (QALYs). Costs were derived from Medicare reimbursement using the perspective of the payer. Probabilities for outcomes and complications were taken from existing literature. Cost-effectiveness was assessed using the incremental cost-effectiveness ratio.

RESULTS

With base case analysis, the total cost was $15,069 when treated with CWU and second-look surgery versus $13,126 when treated with CWU and DW-MRI. The second-look treatment pathway yielded 17.05 QALYs, whereas the DW-MRI pathway yielded 16.91 QALYs in terms of health benefit accrued across the lifetime of the patient. The cost-effectiveness incremental cost-effectiveness ratio was $21,800/QALY. Using the conventional $50,000 willingness-to-pay threshold, second-look surgery was the more cost-effective approach 63.7% of the time by simulation.

CONCLUSIONS

Both treatment pathways were found to be cost-effective, with second-look surgery incrementally cost-effective 63.7% of the time. Assumptions were validated by one-way and Monte Carlo probability sensitivity analysis.

PROFESSIONAL PRACTICE GAP AND EDUCATIONAL NEED

There is ample variation in treatment pathways regarding usage of DW-MRI and second-look surgery for cholesteatoma.

LEARNING OBJECTIVE

To evaluate the cost-effectiveness of DW-MRI and second-look surgery approaches, accounting for health-related quality-of-life outcomes and costs for the duration of the patient lifetimes.

DESIRED RESULT

To inform the discussion on the treatment for cholesteatoma given emergent noninvasive technologies.Level of Evidence: Level III.Indicate IRB or IACUC: Exempt.

Early Magnetic Resonance Imaging to Diagnose Residual Cholesteatoma in Children and Benefit of Radiological Rereview

OBJECTIVE

Non-echo-planar diffusion-weighted (DW) magnetic resonance imaging (non-EPI MRI) is the appropriate sequence to detect residual cholesteatoma. In the child, MRI may be clinically useful to determine the timing of the second-look procedure. The aim of this paper was to retrospectively evaluate the performance of early MRI (before the 18th postoperative month) in detecting residual cholesteatoma in children after review by experienced specialized neuroradiologists.

STUDY DESIGN

Retrospective study.

SETTING

One university center comparative cohort.

METHODS

All patients who had a 2-staged procedure for cholesteatoma with an MRI before the second stage from 2010 to 2020 were included and analyzed. Three pediatric neuroradiologists reviewed all the images blinded to the surgical result.

RESULTS

N = 141 cholesteatoma events (140 children) were included with a mean age at MRI of 10 (±4) years old. Non-EPI MRIs were performed 10.7 (±3.8) months after the first-stage surgery and 2.2 (±2.6) months before the second-stage procedure. Non-EPI MRI had a 0.57 sensitivity (SE) and 0.83 specificity (SP). MRI was reviewed in 112 cases. The diagnosis was corrected in 17 cases (15.1%) (3 true positives, 7 false negatives, and 7 false positives). SE = 0.63 (p = 0.1) and SP = 0.92 (p = 0.08) after rereading.

CONCLUSION

Early MRI's SE is poor but SP is excellent after rereading. Evidence does not support the use of early non-EPI MRI to modify the surgical strategy or to postpone the second look. If performed, early non-EPI MRI should be read by specialized experienced radiologists with all 3 sequences (T1, T2, and non-EPI DW) and apparent diffusion coefficient calculation, especially in cases of otitis media with effusion.

Cartilage grafts mimicking cholesteatoma recurrence on diffusion-weighted magnetic resonance imaging: a case series

BACKGROUND

Cholesteatomas present a high risk for residual and recurrent disease, and the surveillance of post-operative patients can be challenging. Diffusion-weighted magnetic resonance imaging is becoming the preferred method for investigating recidivism; however, false positive imaging findings increase the risk of patients undergoing unnecessary second look surgery.

CASE REPORTS

This study reports two patients with false positive diffusion restriction associated with cartilage grafts that mimicked cholesteatoma and resulted in second look surgery with no disease found at operation. This study also discusses the related medical literature, including potential causes of abnormal diffusion restriction and methods to negate this.

CONCLUSION

Caution should be exercised when considering second look surgery in the presence of a cartilage graft and a high confidence of disease clearance. A multi-disciplinary approach is recommended for the operating surgeon to review the images with a radiologist.

Proposal of a magnetic resonance imaging follow-up protocol after cholesteatoma surgery: a prospective study

BACKGROUND

Non-echo planar (EPI) diffusion-weighted (DW) MRI has become an effective tool for the follow-up after cholesteatoma surgery and decreased the rate of second-look surgeries.

OBJECTIVES

To shed light on the optimal imaging follow-up protocol to detect postoperative residual or recurrent cholesteatoma.

MATERIALS AND METHODS

64 patients were included in this prospective study. Three different surgical procedures were considered: canal-wall-up (26 patients), canal-wall-down (20 patients), and obliterative (18 patients). The imaging follow-up protocol included non-EPI DW MRI during the following postoperative periods: 1 month, 6 months, and 1, 3, 5, and 7 years after the primary surgery.

RESULTS

MRI-positive lesions were present in 18.75% of patients. 50% of the MRI-positive findings occurred at the 1-month follow-up. The other peak of MRI positivity occurred at the 3-year follow-up. The last MRI-positive finding appeared at the 5-year follow-up.

CONCLUSIONS

The timing for the imaging protocol proposed by this prospective study to detect recidivism after cholesteatoma surgery stressed the importance of performing non-EPI DW MRI for detecting residual, though rare, disease. Likewise, extending the follow-up to a least 5 years after primary surgery was also recommended to detect any recurrent cholesteatoma that would appear unlikely to be present beyond this time set.

Post-operative MRI detection of residual cholesteatoma in pediatric patients - The yield of serial scans over a long follow-up

OBJECTIVES

Non-echo-planar diffusion weighted magnetic resonance imaging (Non-EPI DWI MRI) is commonly used for follow-up after cholesteatoma surgery. MRI has a critical role in the evaluation of residual disease, where physical examination will commonly demonstrate an intact tympanic membrane. The aim of our study was to assess the timing of residual cholesteatoma identification on serial MRI scans and the yield of MRI follow up after canal wall up tympano-mastoidectomy.

METHODS

A retrospective chart review of children that underwent canal wall up tympano-mastoidectomy due to cholesteatoma in Schneider Children's Medical Center during 2004-2016, and were followed up both clinically and with MRI.

RESULTS

Seventy-seven children (89 ears) were included, who altogether underwent 166 surgeries (77 revisions). Average follow-up was 66 ± 34.4 months. During follow up, 244 scans were performed; 19 cases of residual disease were diagnosed by MRI and confirmed in surgery. The mean time from surgery and an MRI positive for residual disease was 29.7 ± 16 months (range: 10-66). In 9/19 cases (47%), at least one negative MRI preceded the scan positive for residual disease, and in 4 cases at least two initial scans were negative.

CONCLUSIONS

MRI plays an important role in the diagnosis of residual disease after cholesteatoma surgery. In our cohort. Almost half of the cases diagnosed with residual disease had at least one negative scan prior to the positive one, emphasizing the importance of close radiological follow-up with serial scans after surgery.

Radiological Follow-up After the Bony Obliteration Tympanoplasty in Detecting Residual Cholesteatoma: Towards an Optimal Postoperative MR Imaging Protocol

INTRODUCTION AND AIM

There is no consensus in literature on the most optimal follow-up imaging protocol for non-echoplanar diffusion-weighted magnetic resonance imaging (non-EP DW MRI) after the canal wall-up bony obliteration tympanoplasty. Clearly, no residual cholesteatoma should be missed but on the other hand, unnecessary MR controls should be avoided. The aim of this study is to evaluate the postoperative results of non-EP DW MRI after canal wall-up bony obliteration tympanoplasty surgery at our Institute and to propose an optimal postoperative MR imaging scheme based on our data.

MATERIAL AND METHODS

Retrospective cohort study; all 271 patients who underwent the bony obliteration tympanoplasty between January 2010 and January 2016 with follow-up at our Institute were included. A postoperative MR imaging was systematically performed at 1 year after surgery and repeated at either 5 or both 3 and 5 years after surgery, based on the preferences of the surgeon. Variables of interest were retrieved from electronic patient records.

RESULTS

The median follow-up time was 60 months (inter-quartile range 56-62 mo). Two hundred seventy-one patients (100%) received a 1-year MRI, 107 (39%) a 3-year MRI, and 216 (79.7%%) a 5-year MRI. Residual cholesteatoma was found in nine cases (3.3%), corresponding with an estimated residual rate at 5 years follow-up of 3.7% when using Kaplan-Meier analysis. Of these nine cases, six cases of residual cholesteatoma (66.7%) were detected at the 1-year MRI (12-14 mo postsurgery), two cases (22.2%) at the 3-year MRI (35-39 mo postsurgery), and one case (11.1%) at the 5-year MRI (51 mo postsurgery, in this patient no 3-year MRI was performed). An uncertain MRI result was found in 15 cases, presenting as relatively hyperintense lesions. However, subsequent follow-up scans did not show persistent evidence for residual disease in 14 of these 15 cases.

CONCLUSIONS

A postoperative MRI scan after 1 and 5 years is essential to detect early and late residual cholesteatoma. In our cohort, 22.2% of residual cases were detected at the 3-year MRI. However, this percentage could potentially have been higher when all patients would have received a 3-year MRI. Therefore, in order to detect residual disease as soon as possible, we propose to perform an MRI scan at 1, 3, and 5 years after the bony obliteration tympanoplasty. In cases with an unclear MR result, we suggest a repeat MRI after 12 months.

Optimal Duration of MRI Follow-up to Safely Identify Middle Ear Residual Cholesteatoma

BACKGROUND AND PURPOSE

Previous studies have demonstrated the usefulness of non-EPI DWI for detection of residual cholesteatoma. However, limited data are available to determine the suitable duration of imaging follow-up after a first MR imaging with normal findings has been obtained. The present study aimed to determine the optimal duration of non-EPI DWI follow-up for residual cholesteatoma.

MATERIALS AND METHODS

A retrospective, monocentric study was performed between 2013 and 2019 and included all participants followed up after canal wall up tympanoplasty with at least 2 non-EPI DWI examinations performed on the same 1.5T MR imaging scanner. MR images were reviewed independently by 2 radiologists. Sensitivity and specificity values were calculated as a function of time after the operation. Receiver operating characteristic curves were analyzed to determine the optimal follow-up duration.

RESULTS

We analyzed 47 MRIs from 17 participants. At the end of the individual follow-up period, a residual cholesteatoma had been found in 41.1% of cases. The follow-up duration ranged from 20 to 198 months (mean, 65.9 [SD, 43.9] months). Participants underwent between 2 and 5 non-EPI DWI examinations. Analyses of the receiver operating characteristic curves revealed that the optimal diagnostic value of non-EPI DWI occurred 56 months after the operation when the first MR imaging performed a mean of 17.3 (SD, 6.8) months after the operation had normal findings (sensitivity = 0.71; specificity = 0.7, Youden index = 0.43).

CONCLUSIONS

Repeat non-EPI DWI is required to detect slow-growing middle ear residual cholesteatomas. We, therefore, recommend performing non-EPI DWI for at least the first 5 years after the initial operation.

Application of a novel transcanal keyhole technique in endoscopic cholesteatoma surgery

BACKGROUND

It is difficult to deal with epitympanic cholesteatoma in otologic surgery. The keyhole technique can realize minimally invasive surgery and reconstruct the middle ear canal.

OBJECTIVE

To explore the clinical application of keyhole technique in primary and second-look surgery in middle ear cholesteatoma.

MATERIALS AND METHODS

34 cases were analyzed retrospectively in terms of residual and recurrence rate, safety (adverse events) and hearing performance at long-term follow-up. The application of the technique in primary or second stage operation was evaluated and the operation was performed by transanal endoscopy or combined approach.

RESULTS

The cholesteatoma revealed by CT before operation was limited to the attic in 23 patients, of which 16 had the same imaging range as that of the keyhole technique. The preoperative imaging findings of 11 showed that the attic cholesteatoma may have extended into the mastoid, of which only 6 cases were confirmed by keyhole technique. An endoscopic second-look surgery using the keyhole technique was performed for these patients, 2 were confirmed to have residual lesions in the attic.

CONCLUSIONS

The keyhole technique under otoendoscopy can be used flexibly and conveniently in the second-look surgery to make up for the shortage of diffusion-weighted magnetic resonance imaging.

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.

Reliability of diffusion-weighted magnetic resonance imaging in differentiation of recurrent cholesteatoma and granulation tissue after intact canal wall mastoidectomy

Objective

To assess the reliability of diffusion-weighted magnetic resonance imaging in differentiating recurrent cholesteatoma from granulation tissue after intact canal wall mastoidectomy.

Methods

A prospective study was conducted of 56 consecutive patients with suspected cholesteatoma recurrence after intact canal wall mastoidectomy who underwent diffusion-weighted imaging and delayed contrast magnetic resonance imaging of the temporal bone. The final diagnosis was recurrence in 38 patients and granulation tissue in 18 patients.

Results

Cholesteatoma detection on diffusion-weighted imaging based on two sets of readings had sensitivity of 94.7 and 94.7 per cent, specificity of 94.4 and 88.9 per cent, and accuracy of 94.6 and 92.8 per cent, with good intra-observer agreement (Κ= 0.72,p= 0.001). Cholesteatoma detection on delayed contrast magnetic resonance imaging had sensitivity of 81.6 and 78.9 per cent, specificity of 77.8 and 66.7 per cent, and accuracy of 80.4 and 75.0 per cent, with fair intra-observer agreement (Κ= 0.57,p= 0.001). The mean cholesteatoma diameter on diffusion-weighted imaging was 7.7 ± 1.8 and 7.9 ± 1.8 mm, with excellent intra-observer agreement (Κ= 0.994,p= 0.001).

Conclusion

Diffusion-weighted imaging is a reliable method for differentiating recurrent cholesteatoma and granulation tissue after intact canal wall mastoidectomy.

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.

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.

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.