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

UNLABELLED: 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.

Facial extention of ear pathology: infected cholesteatoma causing a parotid abscess.

A man in his early 30s presented with right-sided preauricular swelling and facial oedema. He had a history of acid injury to his right ear as a child resulting in pinna deformity and subsequent blind sac closure of the external auditory canal. Imaging showed abnormal ear anatomy and abnormal density of the right parotid gland. Antibiotic therapy prevented progression but did not resolve the symptoms. Therefore, the infected area was surgically drained. This showed an underlying cholesteatoma, a benign but locally destructive condition where keratinising squamous epithelium grows in the middle ear and mastoid. The infected region was drained and the cholesteatoma was excised. This led to full resolution of the infection. The patient is awaiting a follow-up diffusion-weighted MRI. This case was unusual as the disease had extended beyond the ear and we therefore wish to alert clinicians to cholesteatoma as a possible cause of facial swelling.

Comparing diffusion weighted MRI in the detection of post-operative middle ear cholesteatoma in children and adults.

INTRODUCTION: There is a limited evidence base for the use of diffusion weighted MRI (DWMRI) in the assessment of post-operative cholesteatoma in children. This is important to address as this technique is particularly relevant in a paediatric setting. METHODS: We searched a prospectively collected database of patients undergoing DWMRI for the assessment of residual and recurrent cholesteatoma. Imaging findings were correlated with findings at revision surgery. 320 investigations were divided into paediatric and adult groups (90 in children, 230 in adults) and compared. RESULTS: Operative findings were available for 158 cases, of which 54 were children. The accuracy of DWMRI in children was 96.3%, and in adults was 88.5%. There were no statistically significant differences in the sensitivity, specificity, positive or negative predictive values between adults and children. DISCUSSION: An increasing number of patients are not undergoing confirmatory surgery after negative DWMRI scans. False negative results are commonly secondary to small foci of disease; false positives have several possible causes. Performing MRI on children can be challenging, but sedation may be helpful in younger children. CONCLUSION: The performance of diffusion weighted MRI is similar in paediatric and adult settings. This study suggests that DWMRI may be used in clinical practice in a similar way in children and adults.

Detecting cholesteatoma with non-echo planar (HASTE) diffusion-weighted magnetic resonance imaging.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of half-Fourier-acquisition single-shot turbo-spin-echo (HASTE) diffusion-weighted magnetic resonance imaging (DWMRI) in the detection of cholesteatoma. STUDY DESIGN: Prospective blinded comparative study. SETTING: London teaching hospital. SUBJECTS AND METHODS: Subjects comprised 32 consecutive patients with suspected primary or residual cholesteatoma. HASTE DWMRI was performed on all patients an average of three months before mastoid surgery and evaluated for the presence of cholesteatoma. Radiological findings were correlated with intraoperative findings. RESULTS: HASTE DWMRI accurately predicted the presence or absence of cholesteatoma in 30 of 32 patients. Residual cholesteatoma was correctly diagnosed by DWMRI in 12 of 14 cases and correctly excluded in six, with two false-negative results caused by movement artifact and keratin pearls less than 2 mm. All primary cholesteatomas were correctly identified. Sensitivity and specificity were 0.93 (95% confidence interval [CI] 0.75-0.99) and 1.00 (95% CI 0.54-1.0), respectively, whereas positive and negative predictive values were 1.00 (95% CI 0.86-1.00) and 0.75 (95% CI 0.35-0.97), respectively. CONCLUSION: Our study supports the increasing but small body of evidence that non-echo-planar imaging (i.e., HASTE) DWMRI performs well in the detection of cholesteatoma. We propose that HASTE DWMRI should be performed on all patients before their second-look surgery to provide valuable information to the operating surgeon.