CT and MR imaging after middle ear surgery

The Efficacy of DW and T1-W MRI Combined with CT in the Preoperative Evaluation of Cholesteatoma

Objective: This study aims to assess the efficacy of diffusion-weighted (DW) and T1-weighted (T1W) magnetic resonance imaging (MRI) combined with high-resolution computed tomography (HRCT) (together as DW-T1W-CT) in the preoperative evaluation of the presence and extent of cholesteatoma, which helps determine whether a patient is suitable for transcanal endoscopic ear surgery (TEES). Methods: This retrospective study included 35 patients (18 male and 17 female) aged from 2 to 81 years diagnosed with chronic otitis media with or without cholesteatoma, who had received surgical treatment and a preoperative MRI and HRCT during the period of December 2015 to December 2020 at Cathay General Hospital. We compared the preoperative DW-T1W-CT findings with the intraoperative findings and final pathologic diagnosis. The accurate predictive value was evaluated using the presence of cholesteatoma and its extent. Results: Regarding the efficacy of detecting cholesteatoma, we found a sensitivity of 92% (23/25 cases with cholesteatoma), a specificity of 90% (9/10 cases without cholesteatoma), and an overall accurate predictive value of 91.4% (32/35) by using combined DW-T1W-CT imaging. With regard to evaluating the extent of cholesteatoma, the combined DW-T1W-CT images obtained an accurate predictive value of 84% (21/25 cases of cholesteatoma). Conclusion: Combined DW-T1W-CT has been proven to be a reliable tool in detecting the presence of cholesteatoma. It is also useful in preoperatively depicting the extent of cholesteatoma, which is crucial for determining whether a patient is suitable for TEES, aiding in surgical planning and patient consultation.

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.

Functional assessment of moisture influenced cadaveric tympanic membrane using phase shift-resolved optical Doppler vibrography

An elevated relative moisture in the external ear canal and middle ear cavity may predispose to chronic otorrhea and related infections along with abnormal tympanic membrane (TM) vibration patterns. Therefore, phase shift-resolved optical Doppler vibrography (ODV) was used for vibration assessments of moisture influenced cadaveric TM. ODV was applied to generate time resolved cross-sectional and volumetric vibrographs of a cadaveric TM, driven acoustically at several frequencies. In order to analyze the effect of moisture on TM, homogenous moisture conditions were provided by soaking the cadaveric TM specimens in 1× phosphate buffer saline with a pH of 7.4. The TM specimen was exposed to a rapidly switchable frequency generator during the ODV image acquisition. The experiment was conducted for 3 hours and the cadaveric TM was exposed to each frequency with an interval of 30 minutes. Acquired phase shift-resolved ODV assessments revealed a depth dependent vibration tendency between the applied frequencies, along with a decline in the moisture level of the cadaveric TM specimen. Thus, the ODV method can aid our understanding of sound conduction in the middle ear, thus supporting the diagnosis of TM diseases.

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.

Review on Otological Robotic Systems: Toward Microrobot-Assisted Cholesteatoma Surgery

Otologic surgical procedures over time have become minimally invasive due to the development of medicine, microtechniques, and robotics. This trend then provides an expected reduction in the patient's recovery time and improvement in the accuracy of diagnosis and treatment. One of the most challenging difficulties that such techniques face are precise control of the instrument and supply of an ergonomic system to the surgeon. The objective of this literature review is to present requirements and guidelines for a surgical robotic system dedicated to middle ear surgery. This review is particularly focused on cholesteatoma surgery (diagnosis and surgical tools), which is one of the most frequent pathologies that urge for an enhanced treatment. This review also presents the current robotic systems that are implemented for otologic applications.

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.

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.

CT Findings in the External Auditory Canal after Transcanal Surgery

BACKGROUND AND PURPOSE

Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.

MATERIALS AND METHODS

Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.

RESULTS

Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.

CONCLUSIONS

CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.

Imaging for evaluation of cholesteatoma: current concepts and future directions

PURPOSE OF REVIEW

To examine the rationale and utility of imaging in patients with known or suspected cholesteatoma, with emphasis on high-resolution computed tomography (HRCT) and diffusion-weighted MRI (DW-MRI).

RECENT FINDINGS

The initial diagnosis of cholesteatoma is largely based on patient history and clinical findings. HRCT scan can be a useful adjunct to define the presence of pathologic soft tissue in the temporal bone, and the extent of bony erosion, and inform the otologic surgeon about expected findings at the time of surgery. Although MRI has not traditionally been used in the evaluation of cholesteatoma given its poor resolution of bone anatomy, recent advances in DW-MRI sequences allow for high sensitivity and specificity in identifying the presence of cholesteatoma. More specifically, non-echo-planar DW-MRI is superior in the detection of residual or recurrent cholesteatoma compared to delayed-contrast MRI and echo-planar DW-MRI.

SUMMARY

HRCT and DW-MRI offer complementary anatomic information that can be used effectively in the management of cholesteatoma. DW-MRI imaging has proven to be a reliable method for detecting residual or recurrent cholesteatomas down to 3 mm in size, and allows radiologic differentiation between cholesteatoma and other soft tissue. As more centers implement DW-MRI imaging for detecting residual or recurrent cholesteatoma, there will likely be less need for second-look surgery, thereby potentially decreasing associated morbidity and surgical costs.

Imaging in otosclerosis: A pictorial review

Otosclerosis is an otodystrophy of the otic capsule and is a cause of conductive, mixed or sensorineural hearing loss in the 2nd to 4th decades of life. Otosclerosis is categorised into two types, fenestral and retrofenestral. Imaging plays an important role in the diagnosis and management of otosclerosis. High-resolution CT (HRCT) of the temporal bone using 1-mm (or less) thick sections is the modality of choice for assessment of the labyrinthine windows and cochlear capsules. MRI has limited application in the evaluation of the labyrinthine capsules but is useful for assessment of the cochlear lumen prior to cochlear implantation in patients with profound hearing loss. The treatment of fenestral otosclerosis is primarily surgical with stapedectomy and prosthesis insertion. Patients with retrofenestral otosclerosis and profound hearing loss are treated medically using fluorides, but may derive significant benefit from cochlear implantation. This pictorial review aims to acquaint the reader with the pathology and clinical features of otosclerosis, the classical imaging appearances on CT and MRI, a radiological checklist for preoperative CT evaluation of otosclerosis, imaging mimics and a few examples of post-stapedectomy imaging and complications. Teaching points • Otosclerosis causes conductive, sensorineural and mixed hearing loss in adults.• HRCT of the temporal bone is the diagnostic imaging modality of choice.• Stapedectomy is used to treat fenestral otosclerosis.• Fluorides and cochlear implantation are used to treat retrofenestral otosclerosis.

Early computed tomography findings of the inner ear after stapes surgery and its clinical correlations

OBJECTIVE

Pneumolabyrinth resulting from temporal bone trauma and stapes luxation has been associated with sensorineural hearing loss (SNHL). The principal purpose of this study was to determine the incidence and volume of pneumolabyrinth after stapedotomy in which iatrogenic perilymphatic fistula is created and to also correlate this with possible hearing loss and vertigo.

STUDY DESIGN

Prospective study.

SETTING

Tertiary referral center.

PATIENTS AND METHODS

Fifty stapedotomy patients were operated on for otosclerosis, and of those 50, 20 underwent high-resolution computed tomography (CT) on the first day, 10 on the third day, and 20 on the seventh day. The patients followed up regarding SNHL and vertigo that could develop postoperatively, and the correlation of such complications with HRCT findings was examined.

RESULTS

The 20 patients who had high-resolution CT (HRCT) on the first day all presented with pneumolabyrinth, and none of the 20 patients who underwent HRCT on the seventh day had pneumolabyrinth. Postoperatively, 92% of the patients had less than 20 dB and 62% had less than 10 dB air-bone gap. None of the patients had SNHL or persistent vertigo. There was no correlation between pneumolabyrinth and hearing loss or vertigo.

CONCLUSION

Pneumolabyrinth is a radiological sign of perilymphatic fistula and has no effect on sensorineural hearing loss and vertigo. Observing pneumolabyrinth during the early postoperative stage should not necessarily implicate a complication; however, pneumolabyrinth after the first week supported with the clinical symptoms of perilymphatic fistula would be a meaningful finding.

Intraoperative Cone-Beam Computed Tomography and Multi-Slice Computed Tomography in Temporal Bone Imaging for Surgical Treatment

Objective

Conventional computed tomography (CT) imaging is the standard imaging technique for temporal bone diseases, whereas cone-beam CT (CBCT) imaging is a very fast imaging tool with a significant less radiation dose compared with conventional CT. We hypothesize that a system for intraoperative cone-beam CT provides comparable image quality to diagnostic CT for identifying temporal bone anatomical landmarks in cadaveric specimens.

Study Design

Cross-sectional study.

Setting

University tertiary care facility.

Subjects and Methods

Twenty cadaveric temporal bones were affixed into a head phantom and scanned with both a prototype cone-beam CT C-arm and multislice helical CT. Imaging performance was evaluated by 3 otologic surgeons and 1 head and neck radiologist. Participants were presented images in a randomized order and completed landmark identification questionnaires covering 21 structures.

Results

CBCT and multislice CT have comparable performance in identifying temporal structures. Three otologic surgeons indicated that CBCT provided statistically equivalent performance for 19 of 21 landmarks, with CBCT superior to CT for the chorda tympani and inferior for the crura of the stapes. Subgroup analysis showed that CBCT performed superiorly for temporal bone structures compared with CT. The radiologist rated CBCT and CT as statistically equivalent for 18 of 21 landmarks, with CT superior to CBCT for the crura of stapes, chorda tympani, and sigmoid sinus.

Conclusion

CBCT provides comparable image quality to conventional CT for temporal bone anatomical sites in cadaveric specimens. Clinical applications of low-dose CBCT imaging in surgical planning, intraoperative guidance, and postoperative assessment are promising but require further investigation.

High-resolution three-dimensional diffusion-weighted imaging of middle ear cholesteatoma at 3.0 T MRI: usefulness of 3D turbo field-echo with diffusion-sensitized driven-equilibrium preparation (TFE-DSDE) compared to single-shot echo-planar imaging

OBJECTIVE

To prospectively evaluate the usefulness of a newly developed high-resolution three-dimensional diffusion-weighted imaging method, turbo field-echo with diffusion-sensitized driven-equilibrium (TFE-DSDE) in diagnosing middle-ear cholesteatoma by comparing it to conventional single-shot echo-planar diffusion-weighted imaging (SS-EP DWI).

MATERIALS AND METHODS

Institutional review board approval and informed consent from all participants were obtained. We studied 30 patients with preoperatively suspected acquired cholesteatoma. Each patient underwent an MR examination including both SS-EP DWI and DSDE-TFE using a 3.0 T MR scanner. Images of the 30 patients (60 temporal bones including 30 with and 30 without cholesteatoma) were reviewed by two independent neuroradiologists. The confidence level for the presence of cholesteatoma was graded on a scale of 0-2 (0=definite absence, 1=equivocal, 2=definite presence). Interobserver agreement as well as sensitivity, specificity, and accuracy for detection were assessed for the two reviewers.

RESULTS

Excellent interobserver agreement was shown for TFE-DSDE (κ=0.821) whereas fair agreement was obtained for SS-EP DWI (κ=0.416). TFE-DSDE was associated with significantly higher sensitivity (83.3%) and accuracy (90.0%) compared to SS-EP DWI (sensitivity=35.0%, accuracy=66.7%; p<0.05). No significant difference was found in specificity (96.7% for TFE-DSDE, 98.3% for SS-EP DWI) CONCLUSION: With increased spatial resolution and reduced susceptibility artifacts, TFE-DSDE improves the accuracy in diagnosing acquired middle ear cholesteatomas compared to SS-EP DWI.

Postmastoidectomy effusion measurement using a delay-line ultrasound transducer: cadaver experiments

Mastoidectomy is a surgical procedure for removing mastoid air cells and has been used widely to establish drainage and cleaning infections from the mastoid bone. Computed tomography (CT) and magnetic resonance imaging (MRI) are the primary instruments used to clinically detect mastoid effusion following surgery. This study examines the feasibility of ultrasonography to detect postsurgical mastoid effusion. In vitro ultrasound measurements were conducted on 10 cadavers. For each sample, mastoidectomy was performed, and saline and whole blood samples were injected into the surgical mastoid cavity to simulate different effusion properties. A 2.25-MHz delay-line ultrasound transducer was used to obtain ultrasound backscattered data from the mastoid. The data were used to analyze echo intensity and the backscattered statistics by estimating the scaling and Nakagami parameters of the Nakagami distribution model. The results show that the scaling and Nakagami parameters can successfully detect mastoid effusion. Specifically, the Nakagami parameter is capable of characterizing the mastoid effusion properties. This indicates that ultrasound measurement based on a combination of delay-line transducer and Nakagami parameter estimation is a potential real-time diagnostic tool for evaluating mastoid effusion following mastoidectomy without radiation exposure.

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

Middle ear cholesteatoma is a common inflammatory disease that requires surgery due to potentially serious intracranial complications. Diagnosis of cholesteatoma is mainly clinical, with computed tomography (CT) used to evaluate disease extension before surgery. Certain patterns of bone erosion are specific, but CT attenuation does not allow differentiation from other inflammatory middle ear diseases. With its high tissue discrimination and contrast resolution, magnetic resonance imaging is valuable in diagnosis of cholesteatomas. Absent enhancement at delayed postcontrast imaging has been used for diagnosis. Diffusion-weighted imaging (DWI) is highly specific due to the high keratin content of cholesteatomas. New non-echo-planar DWI sequences, such as periodically rotated overlapping parallel lines with enhanced reconstruction, are superior to conventional echo-planar DWI, since they minimize susceptibility artifacts at the skull base and increase sensitivity for detection of lesions as small as 2 mm. This technique is indicated when clinical diagnosis is difficult and high tissue specificity is necessary, as in congenital, temporal bone, or atypical acquired middle ear cholesteatomas and residual or recurrent disease after surgery. Non-echo-planar DWI has been proposed for screening of postsurgical (residual or recurrent) cholesteatomas, thus obviating many second-look revision surgeries, especially after more conservative canal wall up surgery.

Advanced imaging technology in surgical innovation

Advanced imaging technologies including computed tomography (CT) and magnetic resonance imaging (MRI) have immensely expanded possibilities in imaging and surgery. The accurate visualization of bones and soft tissue has transformed the surgical management of numerous diseases, including middle ear disease, orthopedic and reconstructive cases, and cancer. In fact, in surgical subspecialties such as neurosurgery, CT and MRI are the diagnostic modalities of choice for preoperative evaluation of patients. Furthermore, the ongoing development of the newer imaging technologies continues to expand image-guided surgical treatments. The development of new radiological modalities combined with the modern training of surgeons will provide an exciting landscape for future practicing physicians.

A systematic review of diffusion-weighted magnetic resonance imaging in the assessment of postoperative cholesteatoma

OBJECTIVE

A systematic review to determine whether the diffusion-weighted (DW) magnetic resonance imaging scan can reliably detect residual or recurrent cholesteatoma after mastoid surgery.

DESIGN

A systematic review.

DATA SOURCES

Databases including EMBASE, MEDLINE, CINAHL, Web of Science, and Cochrane Review were searched for studies published without language restriction from the start of the databases. Additional studies were identified from cited references.

SELECTION CRITERIA

Initial search identified 402 publications, of which 16 studies met the inclusion criteria for the systematic review. The DW imaging (DWI) scan was used to detect residual or recurrent cholesteatoma and subsequent second-look surgery was performed to correlate the findings.

REVIEW METHODS

Studies were assessed for their selection of patients for radiologic investigations, imaging parameters, and subsequent surgery. Outcome measures included sensitivity, specificity, positive and negative predictive values of the DWI, and the incidence and size of residual or recurrent cholesteatoma.

RESULTS

Two different modalities of DWI sequences have been described. Eight studies with 225 patients analyzed echo-planar imaging (EPI) and 8 studies with 207 patients described the "non-EPI" scanning techniques. Non-EPI parameters are more reliable in identifying residual or recurrent cholesteatoma with sensitivity, specificity, and positive and negative predictive values of 91%, 96%, 97%, and 85%, respectively.

CONCLUSION

The available evidence suggests that non-EPI such as half-Fourier acquisition single-shot turbo spin echo sequences are more reliable in identifying residual or recurrent cholesteatoma. This is a promising radiologic investigation; however, we think further studies are required with more patients and long-term results to establish its place as an alternative to a second-stage surgery after canal wall up surgery.

The diagnostic accuracy of non-echo-planar diffusion-weighted imaging in the detection of residual and/or recurrent cholesteatoma of the temporal bone

BACKGROUND AND PURPOSE

Non-EPI DWI is a promising alternative to second-look surgery for the detection of residual and/or recurrent cholesteatoma. We evaluated the diagnostic accuracy, expressed as a positive predictive value, of MR imaging for the detection of residual and/or recurrent cholesteatoma in our hospital.

MATERIALS AND METHODS

Fifty-six MR imaging studies were performed from 2005 to 2010 in patients having previously undergone surgery for cholesteatoma. Pre- and postgadolinium T1-weighted, T2-weighted, and non-EPI DWI sequences were performed and correlated with clinical and intraoperative findings. Twenty-seven patients underwent second-look surgery; 7 were under close clinical follow-up. Twenty-two patients without evidence of cholesteatoma were under regular follow-up (range, 14-44 months).

RESULTS

Non-EPI DWI sequences showed increased DW signal intensity in 36 patients. Of those, 27 had second-look surgery, confirming cholesteatoma in 25 patients; in 1 patient, an empyema was diagnosed, and in the other patient, no cholesteatoma was found at surgery. In 2 patients who had not undergone surgery, increased DW signal intensity was accompanied by hyperintense signal intensity on T1-weighted images, consistent with transplanted fat in the postoperative cavity. The positive predictive value for detection of cholesteatoma was 93% (25/27).

CONCLUSIONS

Residual and/or recurrent cholesteatomas after primary cholesteatoma surgery can be accurately detected by increased DW signal intensity on non-EPI DWI. However, DWI without conventional sequences increased the risk of misdiagnosis in our patient setting because transplanted fat within the postoperative cavity may show increased DW signal intensity.

Detection of middle ear cholesteatoma by diffusion-weighted MR imaging: multishot echo-planar imaging compared with single-shot echo-planar imaging

BACKGROUND AND PURPOSE

Previous reports have shown that DWI is useful in detecting cholesteatoma. SS-EPI is the most widely used DWI technique. However, SS-EPI may have susceptibility artifacts due to field inhomogeneity in the imaging of the temporal bone region. Our purpose was to prospectively evaluate the advantage of MS-EPI for the diagnosis of middle ear cholesteatoma by comparing it with SS-EPI.

MATERIALS AND METHODS

We studied 29 patients with preoperatively suspected acquired cholesteatoma. Each patient underwent an MR imaging examination including both SS-EPI and MS-EPI by using a 1.5T MR imaging scanner. Images of the 29 patients (58 temporal bones including 30 with and 28 without cholesteatoma) were reviewed by 2 independent neuroradiologists. The confidence level for the presence of cholesteatoma was graded on a scale of 0-2 (0 = none, 1 = equivocal, 2 = definite). Interobserver agreement as well as sensitivity, specificity, and accuracy were assessed for the 2 readers.

RESULTS

Excellent interobserver agreement was shown for both MS-EPI (κ = 0.856) and SS-EPI (κ = 0.820). MS-EPI was associated with higher sensitivity (76.7%) and accuracy (87.9%) than SS-EPI (sensitivity = 50.0%, accuracy = 74.1%) (P < .05), while both methods showed 100% specificity.

CONCLUSIONS

Compared with SS-EPI, MS-EPI improves the accuracy of the diagnosis of acquired middle ear cholesteatomas.

CT and MRI Correlations in Patients with Suspected Cholesteatoma after Surgery

The study of postoperative ear cavities in patients who underwent surgery for cholesteatoma is a difficult challenge for radiologists. In our study we make a correlation between CT and MRI findings, useful tools in patients with suspected residual or recurrent cholesteatoma. The use of different MRI sequences especially DWI can help radiologists to discriminate between cholesteatoma and other different processes.

Eye lens radiation exposure and repeated head CT scans: A problem to keep in mind

OBJECTIVES

The deterministic character of radiation-induced cataract is being called into question, raising the possibility of a risk in patients, especially children, exposed to ionizing radiation in case of repeated head CT-scans. This study aims to estimate the eye lens doses of a pediatric population exposed to repeated head CTs and to assess the feasibility of an epidemiological study.

METHODS

Children treated for a cholesteatoma, who had had at least one CT-scan of the middle ear before their tenth birthday, were included. Radiation exposure has been assessed from medical records and telephone interviews.

RESULTS

Out of the 39 subjects contacted, 32 accepted to participate. A total of 76 CT-scans were retrieved from medical records. At the time of the interview (mean age: 16 years), the mean number of CT per child was 3. Cumulative mean effective and eye lens doses were 1.7mSv and 168mGy, respectively.

CONCLUSION

A relatively high lens radiation dose was observed in children exposed to repeated CT-scans. Due to that exposure and despite the difficulties met when trying to reach patients' families, a large scale epidemiological study should be performed in order to assess the risk of radiation-induced cataracts associated with repeated head CT.

[Imaging of the temporal bone]

This article presents a review of diseases of the temporal bone which are relevant for radiologists in routine clinical practice. First the most prominent imaging methods will be briefly summarized with respect to the current state of the art and the most important aspects of cross-sectional anatomy of the temporal bone will be presented. This is followed by the presentation of various inflammatory diseases. Fractures (longitudinal, transverse and mixed fractures), auditory ossicle lesions and contusions of the labyrinth will be discussed in connection with injuries of the temporal bone. Tumors and tumor-like lesions and the clinical symptoms of otosclerosis and malformations will also be discussed. Finally the postoperative use of imaging methods will be presented. Special importance is given to the position of imaging techniques in the diagnostic chain and their evidential value. This is supplemented by special morphological imaging characteristics and aspects of differential diagnostics.

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.

Neuroradiology of cholesteatomas

The relevant aspects of cholesteatomas are reviewed with the emphasis on their diagnosis by using cross-sectional imaging. The indications and limitations of CT and MR imaging and the use of novel MR imaging techniques in the diagnosis of cholesteatomas are described. HRCT of the temporal bone has an excellent spatial resolution, thus even small soft-tissue lesions can be accurately delineated (high sensitivity). However, CT has poor specificity (ie, soft-tissue structures cannot be differentiated). MR imaging with the conventional sequences (T1WI, T2WI, postcontrast T1WI) provides additional information for distinguishing different pathologic entities and for accurately diagnosing primary (nonsurgical) and residual/recurrent (surgical) cholesteatomas. Higher diagnostic specificity is achieved by introducing DW-EPI, delayed postcontrast imaging, DW-non-EPI, and DWI-PROPELLER techniques. Studies using DW-non-EPI and DWI-PROPELLER sequences show promising results related to improved diagnostic sensitivity and specificity for even small (<5 mm) cholesteatomas, thus allowing avoidance of second-look surgery in the future.

Preliminary outcomes of cholesteatoma screening in children using non-echo-planar diffusion-weighted magnetic resonance imaging

OBJECTIVE

Diffusion-weighted (DW) MRI imaging is evolving into an alternative to second look surgery in detection of cholesteatoma recurrence. Insights into the DW MRI appearances of postoperative or inflammatory mucosal changes have recently described using non-echo-planar, turbo spin-echo (TSE) DW MRI which reliably distinguishes between postoperative changes and cholesteatoma. We investigated the use of TSE DW MRI in our pediatric population in order to validate a rapid and cost-effective MRI sequence that can be used to screen for cholesteatoma.

METHODS

Prospective comparative study with adult and pediatric patients at a tertiary referral centre. Patients in the study underwent TSE DW MRI prior to second look or revision surgery for cholesteatoma. A Siemens 1.5 T scanner was employed, using the HASTE sequence (EPI DW MRI) as well as standard echo-planar DWI, T1 and T2 sequences. The MRI findings were then correlated with the intraoperative findings at surgery 9-15 months after primary surgery, or of revision surgery in the cases that were referred from other centres. Detection and localisation of cholesteatoma on TSE DW MRI were compared with the findings at second surgery, long considered the gold standard for detection of residual or recurrent disease. Scanning time between the TSE sequence and the standard planar DW MR were also compared.

RESULTS

In a cohort of 92 patients, 21 pediatric patients were identified. 15 patients have had their 15 second look or revision procedures and DW MRI prior to their surgery. TSE DW MRI detected cholesteatoma and reliably identified the location of the cholesteatoma in 2 patients whom all had disease confirmed at surgery. The 13 cases with negative preoperative DW MRI for cholesteatoma were all confirmed to be disease free at surgery. Scanning time of the TSE sequence takes 100 s as opposed to 20 min using standard echo-planar DW MRI techniques without the requirement of a contrast agent and without the need for a general anaesthetic for any of the children.

CONCLUSION

TSE (HASTE) DW MRI is emerging as a cost effective, noninvasive alternative to second look surgery for detection and screening for cholesteatoma in pediatric patients.

Apparent diffusion coefficient values of middle ear cholesteatoma differ from abscess and cholesteatoma admixed infection

A retrospective study was conducted on a cohort of 15 patients who underwent surgery because cholesteatoma or abscess was suspected. All patients had MR imaging prior to surgery with diffusion-weighted images (DWI) from which the apparent diffusion coefficient (ADC) value was calculated. Using this technique, we were able to determine 3 distinct ADC value ranges corresponding to the 3 groups of lesions found at surgery (pure cholesteatoma, cholesteatoma with infection, and abscess or infection). This needs to be confirmed by further studies with a wider range of patients.

Diffusion-weighted MR imaging in postoperative follow-up: reliability for detection of recurrent cholesteatoma

INTRODUCTION

Cholesteatoma is a progressively growing process that destroy the neighboring bony structures and treatment is surgical removal. Follow-up is important in the postoperative period, since further surgery is necessary if recurrence is present, but not if granulation tissue is detected. This study evaluates if diffusion-weighted MR imaging alone can be a reliable alternative to CT, without use of contrast agent for follow-up of postoperative patients in detecting recurrent cholesteatoma.

MATERIALS AND METHODS

26 consecutive patients with mastoidectomy reporting for routine follow-up CT after mastoidectomy were included in the study, if there was loss of middle ear aeration on CT examination. MR images were evaluated for loss of aeration and signal intensity changes on diffusion-weighted sequences. Surgical results were compared with imaging findings.

RESULTS

Interpretation of MR images were parallel with the loss of aeration detected on CT for all 26 patients. Of the 26 patients examined, 14 were not evaluated as recurrent cholesteatoma and verified with surgery (NPV: 100%). Twelve patients were diagnosed as recurrent cholesteatoma and 11 were surgically diagnosed as recurrent cholesteatoma (PPV: 91.7%). Four of these 11 patients had loss of aeration size greater than the high signal intensity area on DWI, which were surgically confirmed as granulation tissue or fibrosis accompanying recurrent cholesteatoma.

CONCLUSION

Diffusion-weighted MR for suspected recurrent cholesteatoma is a valuable tool to cut costs and prevent unnecessary second-look surgeries. It has the potential to become the MR sequence of choice to differentiate recurrent cholesteatoma from other causes of loss of aeration in patients with mastoidectomy.

Postoperative non-echo-planar diffusion-weighted magnetic resonance imaging changes after cholesteatoma surgery: implications for cholesteatoma screening

OBJECTIVES

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is emerging as an alternative to second-look surgery in ruling out residual or recurrent disease after cholesteatoma eradication. However, the DW MRI appearances of postoperative or inflammatory mucosal changes have not been well investigated, thus rendering the interpretation of postoperative DW MRI difficult in the presence of mucosal reactions. We investigated the turbo-spin echo (TSE) DW MRI changes of the middle ear and mastoid mucosa after cholesteatoma surgery and compared these with the TSE DW MRI features of cholesteatoma with an aim to identify a rapid and cost-effective purely DW MRI sequence that can be used to screen for cholesteatoma.

STUDY DESIGN

A prospective comparative study.

SETTING

A tertiary referral center in Western Australia.

PATIENTS

Patients undergoing revision or second-look cholesteatoma surgery.

INTERVENTION

Patients underwent 3 to 6 monthly half-Fourier-acquisition single-shot turbo-spin-echo TSE DW MRI before their second surgery. The MRI findings were then correlated with the intraoperative findings at second-look surgery 6 to 17 months after primary surgery or of revision surgery in the cases that were referred from other centers.

MAIN OUTCOME MEASURE

Detection of cholesteatoma and noncholesteatoma mucosal changes on TSE DW MRI, compared with the gold standard of findings at second surgery.

RESULTS

Twenty-two patients underwent 23 second-look or revision procedures. All patients had DW MRI before their "second-look" or revision surgery. TSE DW MRI detected cholesteatomas in 7 patients whom all had disease confirmed at second-look or revision surgery. In 16 cases shown to be negative on DW MRI for cholesteatoma, all were confirmed to be disease-free on second-look surgery. Cholesteatomas were shown to produce a TSE DW MRI signal clearly distinct from the spectrum of imaging findings encountered in postoperative mucosal changes.

CONCLUSION

TSE DW MRI holds great promise in screening for cholesteatoma as an alternative to exploratory second-look surgery.

3T MR imaging of postoperative recurrent middle ear cholesteatomas: value of periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted MR imaging

BACKGROUND AND PURPOSE

MR diagnostic of postoperative recurrent cholesteatomas is difficult. Our purpose was to compare multishot fast spin-echo periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted MR imaging (DWI) with array spatial sensitivity encoding technique (ASSET) single-shot echo-planar DWI and late postgadolinium T1-weighted MR imaging for the detection of postoperative recurrent middle ear cholesteatomas with a 3T imaging unit.

MATERIALS AND METHODS

Thirty-five patients with suggested postoperative recurrent middle ear cholesteatoma underwent 3T MR imaging with PROPELLER DWI, ASSET echo-planar DWI, and late postgadolinium T1-weighted MR imaging. Three radiologists (2 seniors, 1 fellow) analyzed unlabeled images for visualization of recurrence. Interobserver and intraobserver agreement was assessed by using the Cohen kappa statistic test. Sensitivity, specificity, and predictive value were assessed for the 3 observers.

RESULTS

Nineteen recurrent cholesteatomas were diagnosed. PROPELLER interobserver agreement was very good (1, 0.89, 0.89) among the 3 observers. Intraobserver agreement between PROPELLER and T1-weighted imaging was very good to moderate (0.88, 0.57, 0.58). PROPELLER DWI provided less interobserver variability than other sequences, and the best sensitivity, specificity, and predictive value.

CONCLUSIONS

On a 3T imaging unit, multishot fast spin-echo PROPELLER DWI allows an easier detection of postoperative recurrent middle ear cholesteatoma than T1-weighted imaging by reducing artifacts and by its better contrast. DWI with PROPELLER is diagnostically robust and accurate.

[Significance of computed tomography evaluation before revision stapes surgery]

BACKGROUND

Stapedectomy and, more recently, stapedotomy have been widely accepted as the primary surgical techniques to improve conductive hearing in patients suffering from otosclerosis. Unsuccessful outcomes are infrequent, but revision surgery may become necessary. We have analyzed the value of computed tomography (CT) scanning following unsuccessful stapes surgery.

PATIENTS AND METHODS

In a total of 37 CT scans, the depth of insertion, angle between prosthesis and footplate, location of prosthesis within the oval niche, visibility of the prosthesis, dehiscence of the superior semicircular canal, and extent of otospongiotic foci were evaluated and compared with the audiometric results.

RESULTS

There was no significant correlation between CT parameters and audiologic results, except for patients with cochlear otosclerosis or lateral dislocation of the piston. One previously unknown dehiscence of the superior semicircular canal was diagnosed. Otospongiotic foci were seen in 13 ears (35%).

CONCLUSION

Displacements of the stapes piston and rare causes for an insufficient result, such as a dehiscence of the superior semicircular canal, can be diagnosed accurately by CT. However, correlation between the audiologic results and the findings on CT scans was possible in only a few cases. Nevertheless, CT scans provide additional information for surgical planning in revision stapes surgery and may become increasingly important to reduce unanticipated intraoperative risks; they may even guide the surgeon not to perform unnecessary revision surgeries.

Comparison of echo-planar diffusion-weighted imaging and delayed postcontrast T1-weighted MR imaging for the detection of residual cholesteatoma

BACKGROUND AND PURPOSE

Echo-planar diffusion-weighted imaging (DWI) and delayed postcontrast T1-weighted MR imaging (DPI) have been proposed in previous studies to detect residual middle ear cholesteatomas, with varying results. We assessed and compared these 2 techniques in patients with canal wall-up tympanoplasty.

MATERIALS AND METHODS

This was a prospective cohort study. Patients who underwent surgery for middle ear cholesteatoma had CT scanning 9 months after the surgery. If opacity was observed (64%) on CT scans, DWI and DPI were performed before second-look surgery. CT, MR imaging, and surgical data were available for 31 patients. Charts were reviewed independently by 3 blinded examiners. Interobserver agreement for MR imaging was calculated (Cohen kappa). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for these techniques: 1) alone or in association, and 2) according to the residual cholesteatoma size measured during surgery.

RESULTS

Interobserver agreement was better for DWI (kappa = 0.81) than for DPI (kappa = 0.51). Sensitivity, specificity, PPV, and NPV values were 60%, 72.73%, 80%, and 50%, respectively, with DWI; and 90%, 54.55%, 78.26%, and 75%, respectively, with DPI. With cholesteatomas >5 mm, the sensitivity and specificity of DWI reached 100% and 88%, respectively, with values for DPI reaching 100% and 80%, respectively. The association of both techniques only allowed improvements in the specificity for lesions >5 mm.

CONCLUSIONS

Both techniques gave acceptable results for residual cholesteatoma detection. DWI is more specific but less sensitive than DPI. Their concurrent use may benefit patients by avoiding undue surgery.

CT versus MR: still a tough decision

CT and MRI are the two most widely used imaging modalities for evaluating head and neck pathology. There is continued controversy in the literature about which modality is superior for imaging different areas of the head and neck. This article summarizes the literature supporting the use of CT, MRI, or both for specific clinical scenarios in otolaryngology. Familiarity with the benefits and potential pitfalls of each modality allows referring physicians and radiologists to tailor imaging regimens to the needs of individual patients.

[Cholesterol granuloma]

AIM OF THE STUDY

We report 2 cases (52 and 29-year-old men) of CG in the petrous apex we treated in 2004-2006. We also review the literature and discus the mechanism of development of CG and the treatment of this lesion.

MATERIAL AND METHODS

Cholesterol granuloma (CG) is a chronic inflammatory process with associated foreign body reaction to hemorrhage-related cholesterol crystals. Although CG is found in various organs the temporal bone is the most common site of detection. Numerous ethiopathological hypotheses have been proposed but most authorities support the concept of air cell tract blockage in well pneumatized petrous apex. Obstruction of the air cells leads to rupture of blood vessels and hemorrhage. Red blood cell degradation into cholesterol crystals produces a foreign body giant-cell reaction with progressive accumulation of typical brownish glistening fluid. Clinically, this lesion can produce sensorineural hearing loss, tinnitus, hemifacial spasm, facial numbness and trigeminal neuralgia. Cholesteatoma is the main lesion to distinguish from CG. On MRI studies, CG appears with a high signal on both T1- and T2-weighted sequences, cholesteatoma appear bright only on T2-weighted ones. Goal of the surgery is to create a drainage and ventilation of the affected area to prevent recurrence. Several alternative approaches to the petrous apex have been described.

RESULTS

12-18 months follow up shows no clinical signs of recurrence.

[Value of diffusion-weighted MR imaging in the detection of middle ear cholesteatoma]

OBJECTIVE

This study, was conducted to determine the clinical value of diffusion-weighted MR imaging (DWI) in detecting the presence of cholesteatoma.

SUBJECT AND METHODS

Fifty-six patients (21 female and 35 male patients; mean age, 43 years) who underwent middle ear surgery were referred to the radiology department for a preoperative DWI study.

RESULTS

DWI depicted 41 out of 48 cholesteatomas involving the middle ear cavity (sensitivity, 85.4%). Seven patients with middle ear cholesteatoma who showed negative DWI findings (false-negative cases) had limited keratin accumulation due to simple atelectasis or meticulous evacuation of keratin debris before the MRI study. No falsepositive cases were found in this study (specificity, 100%). The positive predictive value and negative predictive value were 100% and 53.3%, respectively. The minimum size of middle ear cholesteatoma detected by the current MRI system was 5mm.

CONCLUSION

Diffusion-weighted MR imaging was useful for the detection of middle ear cholesteatoma.

Cholesterol granuloma surrounding the endolymphatic sac

We report a unique case of cholesterol granuloma (CG) surrounding the endolymphatic sac (ES). A 49-year-old man presented with the left side of sensorineural hearing loss, tinnitus, and vertigo. Magnetic resonance and computed tomography imaging revealed a CG surrounding the left ES. The patient initially underwent left transmastoid surgical resection of the tumor. At the time of surgery, brown fluid was aspirated from the tumor, but no other tumors were found. Histopathological examination revealed that the tumor contained cholesterol crystals, confirming the diagnosis of CG. At his 12-month postoperative follow-up, there was no evidence of recurrence. We discuss the radiology, pathology, and surgical removal of CGs surrounding ES.

High-Resolution Computed Tomography of Temporal Bone

The purpose of this 4-part series is to illustrate the nuances of temporal bone anatomy using a high-resolution (200 micro isotropic) prototype volume computed tomography (CT) scanner. The normal anatomy in axial and coronal sections is depicted in the first and second parts. In this, the fourth part, and the third part, the structures that are removed and/or altered in 9 different surgical procedures are color coded and inscribed in the same coronal (article IV) and axial (article III) sections. The text stresses clinically important imaging features, including the normal postoperative appearance, and common complications after these operations. The superior resolution of the volume CT images is vital to the comprehensive and accurate representation of these operations. Minuscule intricate structures that are currently only localized in the mind's eye because of the resolution limit of conventional CT are clearly seen on these scans. This enhanced visualization, together with the information presented in the text, should assist in interpreting temporal bone scans, communicating with surgeons, and teaching this complex anatomy.

High-resolution computed tomography of temporal bone: Part III: Axial postoperative anatomy

The purpose of this 4-part series is to illustrate the nuances of temporal bone anatomy using a high-resolution (200-mu isotropic) prototype volume computed tomography (CT) scanner. The normal anatomy in axial and coronal sections is depicted in the first and second parts. In this and the subsequent part, the structures that are removed and/or altered in 9 different surgical procedures are color coded and inscribed in the same axial (article III) and coronal (article IV) sections. The text stresses clinically important imaging features, including the normal postoperative appearance, and common complications after these operations. The superior resolution of the volume CT images is vital to the comprehensive and accurate representation of these operations. Minuscule intricate structures that are currently only localized in the mind's eye because of the resolution limit of conventional CT are clearly seen on these scans. This enhanced visualization, together with the information presented in the text, should assist in interpreting temporal bone scans, communicating with surgeons, and teaching this complex anatomy.

Imagerie des échecs et complications post-opératoires de la chirurgie de l’otospongiose

Otosclerosis (OS) is a dysplasia of the otic capsule located in most cases on the anterior margin of the oval window or fissula ante fenestrum. Progressive conductive hearing loss is the major clinical symptom, due to stapedovestibular ankylosis. Stapes surgery is the only effective treatment of OS, with excellent functional results in more than 90% of cases. However, failures and complications of the surgery may be observed. In theses cases, the etiologic work-up includes imaging evaluation (CT and MRI). Imaging findings are extremely useful in the therapeutic decision. Surgical failure represents 80% of the causes for surgical revision. The main causes of failure are: displacement of the prosthesis, fibrosis of the oval window, erosion of the long process of the incus, incudo-mallear dislocation, obliterative otosclerosis. CT is essential for diagnosis. MR imaging is rarely indicated in the work-up of surgical failures. Labyrinthine complications account for less than 20% of surgical revisions. Etiologies of labyrinthine complications are: intravestibular penetration of the prosthesis, perilymphatic fistula, intra-vestibular granuloma, labyrinthitis and intravestibular bleeding. CT and MRI are complementary for the work up of these complications.

Diffusion-weighted MR imaging sequence in the detection of postoperative recurrent cholesteatoma

PURPOSE

To prospectively evaluate a fast spin-echo (SE) diffusion-weighted sequence for magnetic resonance (MR) imaging of recurrent cholesteatoma in patients who have undergone middle ear surgery.

MATERIALS AND METHODS

The study was approved by the institutional review board, and informed consent was obtained from all patients. Twenty-four patients (10 female and 14 male patients; mean age, 44 years) who had undergone resection of cholesteatoma were referred for MR imaging. MR imaging was performed with a 1.5-T unit by using unenhanced diffusion-weighted fast SE imaging at b factors of 0 and 800 sec/mm(2), unenhanced T2-weighted fast SE imaging, unenhanced T1-weighted SE imaging, and delayed contrast material-enhanced T1-weighted imaging. Two radiologists evaluated the diffusion-weighted fast SE images for the presence of a high-signal-intensity cholesteatoma. Results from MR imaging were compared with reports from second- or third-look surgery. Interobserver agreement was assessed with the kappa statistic.

RESULTS

A recurrent cholesteatoma was correctly identified in 13 of 14 patients with diffusion-weighted fast SE images obtained with a b factor of 800 sec/mm(2), for a positive predictive value of 93%. In patients without recurrent cholesteatoma, all diffusion-weighted fast SE MR images obtained with a b factor of 800 sec/mm(2) were correctly interpreted as showing no high signal intensity. Thus, the negative predictive value was 100%. Sensitivity and specificity were 100% (13 of 13 patients) and 91% (10 of 11 patients), respectively. Interobserver agreement was excellent (kappa = 0.92). The smallest recurrent cholesteatoma was 5 mm in diameter, and this was correctly detected with the diffusion-weighted fast SE sequence.

CONCLUSION

Diffusion-weighted fast SE imaging enables the depiction of recurrent cholesteatoma in patients who have undergone middle ear surgery.

Detection of postoperative relapsing/residual cholesteatomas with diffusion-weighted echo-planar magnetic resonance imaging

PURPOSE

To assess the capability of echo-planar diffusion-weighted magnetic resonance imaging (MRI) (EPI-DWI) in diagnosing relapsing/residual cholesteatomas after canal wall-up mastoidectomy.

MATERIALS AND METHODS

In a blinded study design, we investigated with MRI, including standard spin-echo sequences, 18 patients evaluated with clinical examination and computed tomography (CT) suspected for relapsing/residual cholesteatoma 7 to 19 months after a canal wall-up mastoidectomy. Images were evaluated by two radiologists blinded to patients' identities, CT findings, and clinical data set, who decided in a consensus agreement whether there was a pathologic signal increase in the petrous bone in a single-shot EPI-DWI sequence. All the patients underwent a second tympanoplasty or revision surgery of the mastoidectomy cavity within 15 days after magnetic resonance investigation.Sensitivity, specificity, and predictive values were evaluated separately for standard sequences and EPI-DWI.

RESULTS

In EPI-DWI, five of six patients with cholesteatoma showed a bright signal, whereas those patients with a noncholesteatomatous tissue showed no anomalies. The only misdiagnosed cholesteatoma was a pearl 2 mm in diameter. Sensitivity, specificity, and positive predictive values, and negative predictive values of EPI-DWI in diagnosing relapsing/residual cholesteatomas were 86, 100, 100, and 92%, respectively.

CONCLUSION

EPI-DWI may be a useful tool in differentiating between cholesteatomatous and noncholesteatomatous tissues after closed cavity mastoidectomy. Further investigations are, however, required to establish the practical utility of EPI-DWI on larger series as a screening modality in the follow-up after closed cavity mastoidectomies.