The utility of diffusion-weighted imaging for cholesteatoma evaluation

Imaging of skull base pathologies: Role of advanced magnetic resonance imaging techniques

Imaging plays a vital role in evaluation of skull base pathologies as this region is not directly accessible for clinical evaluation. Computerized tomography (CT) and magnetic resonance imaging (MRI) have played complementary roles in the diagnosis of the various neoplastic and non-neoplastic lesions of the skull base. However, CT and conventional MRI may at times be insufficient to correctly pinpoint the accurate diagnosis. Advanced MRI techniques, though difficult to apply in the skull base region, in conjunction with CT and conventional MRI can however help in improving the diagnostic accuracy. This article aims to highlight the importance of advanced MRI techniques like diffusion-weighted imaging, susceptibility-weighted imaging, perfusion-weighted imaging, and MR spectroscopy in differentiation of various lesions involving the skull base.

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

BACKGROUND

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Quantitative evaluation of diffusion-weighted imaging techniques for the purposes of radiotherapy planning in the prostate

OBJECTIVE

Diffusion-weighted imaging (DWI) is an important technique for the localization of prostate cancer, and its response assessment during treatment with radiotherapy (RT). However, it has known limitations in terms of distortions and artefacts using standard acquisition techniques. This study evaluates two alternative methods that offer the promise of improved image quality and the potential for more reliable and consistent diffusion data.

METHODS

Three DWI techniques were investigated; single-shot echoplanar imaging (EPI), EPI combined with reduced volume excitation (ZOOMit; Siemens Healthcare, Erlangen, Germany) and read-out segmentation with navigator-echo correction (RESOLVE; Siemens Healthcare). Daily measurements of apparent diffusion coefficient (ADC) value were made in a quality assurance phantom to assess the repeatability of each sequence. In order to evaluate the geometric integrity of these sequences, ten normal volunteers were scanned, and the prostate was contoured to compare its similarity with T2 weighted images.

RESULTS

Phantom ADC values were significantly higher using the standard EPI sequence than those of the other two sequences. Differences were also observed between sequences in terms of repeatability, with RESOLVE and EPI performing better than ZOOMit. Overall, the RESOLVE sequence provided the best agreement for the in vivo data with smaller differences in volume and higher contour similarity than T2 weighted imaging.

CONCLUSION

Important differences have been observed between each of the three techniques investigated with RESOLVE performing the best overall. We have adopted this sequence for routine RT simulation of prostate patients at Liverpool Cancer Therapy Centre.

ADVANCES IN KNOWLEDGE

This work will be of interest to the increasing number of centres wanting to incorporate quantitative DWI in a clinical setting.

Updates and knowledge gaps in cholesteatoma research

The existence of acquired cholesteatoma has been recognized for more than three centuries; however, the nature of the disorder has yet to be determined. Without timely detection and intervention, cholesteatomas can become dangerously large and invade intratemporal structures, resulting in numerous intra- and extracranial complications. Due to its aggressive growth, invasive nature, and the potentially fatal consequences of intracranial complications, acquired cholesteatoma remains a cause of morbidity and death for those who lack access to advanced medical care. Currently, no viable nonsurgical therapies are available. Developing an effective management strategy for this disorder will require a comprehensive understanding of past progress and recent advances. This paper presents a brief review of background issues related to acquired middle ear cholesteatoma and deals with practical considerations regarding the history and etymology of the disorder. We also consider issues related to the classification, epidemiology, histopathology, clinical presentation, and complications of acquired cholesteatoma and examine current diagnosis and management strategies in detail.

Diagnostic capacity of non-echo planar diffusion-weighted MRI in the detection of primary and recurrent cholesteatoma

INTRODUCTION AND AIMS

the aim of this study was to determine the certainty of non-echo-planar imaging diffusion-weighted magnetic resonance imaging (non-EPI DW MRI) in the diagnosis of primary and recurrent cholesteatoma in patients with clinical suspicion of cholesteatoma, assessing the sensitivity and specificity of the test in both groups.

METHODS

Seventy-five patients with clinical suspicion of cholesteatoma were included in our study. Forty-eight cases had primary suspicion of cholesteatoma and 27 cases had recurrent suspicion of cholesteatoma. All patients received non-EPI DW MRI tests before surgery, and radiological and surgical findings were compared.

RESULTS

Sensitivity, specificity and the positive and negative predictive value for primary diagnosis of cholesteatoma group were 91.2%, 50%, 81.6% and 70%, respectively. For the recurrent cholesteatoma group these results were 100%, 66.7%, 90.9% and 100%, respectively.

CONCLUSION

Non-echo-planar imaging diffusion-weighted magnetic resonance imaging is a high sensitivity imaging test for detecting cholesteatoma, for both primary diagnosis and for recurrent cases.

Magnetic resonance imaging acquisition techniques for radiotherapy planning

Magnetic resonance imaging (MRI) has a number of benefits for the planning of radiotherapy (RT), but its uptake into clinical practice has often been restricted to specialist research sites. There is often a lack of detailed MRI knowledge within the RT community and an apprehension of geometric distortions, both of which prevent its best utilization and merit the introduction of a standardized approach and common guidelines. This review sets out to address some of the issues involved in acquiring MRI scans for RT planning in the context of a number of clinical sites of interest and concludes with recommendations for its best practice in terms of imaging protocol and quality assurance. The article is of particular interest to the growing number of cancer therapy centers that are embarking on MRI simulation on either existing systems or their own dedicated scanners.

Diffusion weighted MR imaging of primary and recurrent middle ear cholesteatoma: an assessment by readers with different expertise

Introduction and Purpose. Diffusion weighted imaging (DWI) has been proven to be valuable in the diagnosis of middle ear cholesteatoma. The aims of our study were to evaluate the advantage of multi-shot turbo spin echo (MSh TSE) DWI compared to single-shot echo-planar (SSh EPI) DWI for the diagnosis of cholesteatoma. Material and Methods. Thirty-two patients with clinical suspicion of unilateral cholesteatoma underwent preoperative MRI (1.5T) with SSh EPI and MSh TSE. Images were separately analyzed by 4 readers with different expertise to confirm the presence of cholesteatoma. Sensitivity, specificity, diagnostic accuracy, and positive (PPV) and negative predictive values (NPV) were assessed for each observer and interrater agreement was assessed using kappa statistics. Diagnosis was obtained at surgery. Results. Overall MSh TSE showed higher diagnostic accuracy and lower negative predictive value (NPV) compared to conventional SSh EPI. Interreader agreement between the observers revealed the superiority of MSh TSE compared to SSh EPI. Interrater agreement among all the four observers was higher by using MSh TSE compared to SSh EPI. Conclusion. Our findings suggest that MSh TSE DWI has higher sensitivity for detection of cholesteatoma and lower probability of misdiagnosis. MSh TSE DWI is useful in guiding less experienced observers to the diagnosis.

Long-term surgical and functional outcomes of the intact canal wall technique for middle ear cholesteatoma in the paediatric population

In this paper, we report the postoperative outcomes in canal wall up procedures with second stage surgery in 40 children undergoing intervention for cholesteatoma of the middle ear. The residuals, recurrences and the hearing results were analysed. All 40 patients had a follow-up of at least five years. Of the 39 patients who underwent two staged surgery, 18 (46.1%) had a residual lesion that was identified and excised during the second surgery. Over a five year follow-up period, there were five (12.5%) patients with recurrences, all belonging to the group in whom a residual cholesteatoma was identified during the second staged surgery. The rate of residual cholesteatoma tends to decrease as age increases. The type of cholesteatoma, acquired or congenital middle ear, were not statistically related to the incidence of residual cholesteatoma. Hearing analysis showed that hearing recovery was excellent with canal wall up procedures and remained stable over five years.

Use of non-echo-planar diffusion-weighted MR imaging for the detection of cholesteatomas in high-risk tympanic retraction pockets

BACKGROUND AND PURPOSE

Non-echo-planar DWI MR imaging (including the HASTE sequence) has been shown to be highly sensitive and specific for large cholesteatomas. The purpose of this study was to determine the diagnostic accuracy of HASTE DWI for the detection of incipient cholesteatoma in high-risk retraction pockets.

MATERIALS AND METHODS

This was a prospective study of 16 patients who underwent MR imaging with HASTE DWI before surgery. Surgeons were not informed of the results, and intraoperative findings were compared against the radiologic diagnosis. Sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

Among the 16 retraction pockets, 10 cholesteatomas were diagnosed intraoperatively (62.5%). HASTE showed 90% sensitivity, 100% specificity, 100% positive predictive value, and 85.7% negative predictive value in this group of patients. We found only 1 false-negative finding in an infected cholesteatoma.

CONCLUSIONS

We demonstrate a high correlation between HASTE and surgical findings, suggesting that this technique could be useful for the early detection of primary acquired cholesteatomas arising from retraction pockets and could help to avoid unnecessary surgery.

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.

"Dazed and diffused": making sense of diffusion abnormalities in neurologic pathologies

To review diffusion abnormalities seen in diffusion-weighted MRI in neurological pathologies. We examine the clinical significance of the abnormalities in a broad spectrum of neurological diseases and highlight our current understanding of their causes. Diffusion abnormalities seen on diffusion-weighted MRI can play an important role in the diagnosis and follow-up of a broad spectrum of neurological diseases. A thorough understanding of the appearance and significance of these abnormalities is critical in patient management.

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.

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.

MRI findings of a middle ear cholesteatoma in a dog

This article describes the MRI features of a middle ear cholesteatoma in an 8 yr old flat-coated retriever. Physical examination revealed pain on opening the jaw, and otoscopic examination showed tympanic membrane rupture associated with hyperplastic tissue at the entrance of the middle ear. Standard MRI sequences allowed for the identification of a severely expanded bulla containing material that was isointense to brain tissue on T1-weighted images and of mixed intensity on T2-weighted and fluid-attenuated inversion recovery sequences. No postcontrast enhancement of the content was present, but the lining of the bulla was partially enhanced. The images allowed evaluation of the surgical margins and the secondary changes due to the expansion of the mass. Surgery was performed and histopathology confirmed the presumptive diagnosis of cholesteatoma. In the present case, MRI appeared to serve as a good alternative to computed tomography for the diagnosis of cholesteatoma.

Diffusion-weighted MR imaging in the head and neck

Extracranial applications of diffusion-weighted (DW) magnetic resonance (MR) imaging are gaining increasing importance, including in head and neck radiology. The main indications for performing DW imaging in this relatively small but challenging region of the body are tissue characterization, nodal staging, therapy monitoring, and early detection of treatment failure by differentiating recurrence from posttherapeutic changes. Lower apparent diffusion coefficients (ADCs) have been reported in the head and neck region of adults and children for most malignant lesions, as compared with ADCs of benign lesions. For nodal staging, DW imaging has shown promise in helping detect lymph node metastases, even in small (subcentimeter) nodes with lower ADCs, as compared with normal or reactive nodes. Follow-up of early response to treatment is reflected in an ADC increase in the primary tumor and nodal metastases; whereas nonresponding lesions tend to reveal only a slight increase or even a decrease in ADC during follow-up. Optimization and standardization of DW imaging technical parameters, comparison of DW images with morphologic images, and increasing experience, however, are prerequisites for successful application of this challenging technique in the evaluation of various head and neck pathologic conditions.

Diagnostic accuracy of non-echo-planar diffusion-weighted MRI versus other MRI sequences in cholesteatoma

INTRODUCTION

Non-echo-planar imaging (EPI) MRI has been recently introduced to improve the detection of small-sized cholesteatoma and decrease different artefacts occurring in the EPI-diffusion-weighted (DW) technique. This technique is also time saving in comparison to delayed post-contrast imaging. We prospectively assessed the diagnostic accuracy of MRI including delayed post-contrast standard MRI, EPI and non-EPI-DW sequences in the detection of middle ear cholesteatoma.

METHODS

We evaluated 35 patients suspected of having cholesteatoma who underwent MRI including delayed post-contrast MRI, EPI and non-EPI-DW sequences prior to their planned surgery, and the MR findings were compared with surgical findings. Two experienced radiologists reported the images. Sensitivity, specificity and predictive values of MRI were estimated.

RESULTS

We detected 26 cases of cholesteatoma at surgery. Sensitivity and specificity of delayed post-contrast MRI, EPI DW and non-EPI DW were 73.1 and 77.8%, 61.5 and 88.9%, and 96.2 and 100%, respectively, as interpreted by the first radiologist. Sensitivity and specificity of delayed post-contrast MRI, EPI-DW sequence and non-EPI-DW sequence were 84.6 and 88.9%, 50 and 88.9%, and 92.3 and 100%, respectively, as interpreted by the second radiologist.

CONCLUSION

The non-EPI MRI technique is a more accurate method in detecting middle ear cholesteatoma in comparison to other conventional sequences.

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.

Diagnostic and surgical challenge: middle ear dermoid cyst in 12 month old with branchio-oto-renal syndrome and multiple middle-ear congenital anomalies

Described is the first case report, to our knowledge, of a middle-ear dermoid in a child with branchio-oto-renal (BOR) syndrome. Radiographic, pathologic, and intraoperative figures are shown. This was a diagnostic and surgical challenge as the presentation was similar to a congenital cholesteatoma and the child had numerous significant temporal bone abnormalities. After the intraoperative findings suggested a non-destructive process, the treatment strategy was altered. This case reiterates the need for a cautious, flexible operative approach in a syndromic child. Included is a relevant review of the literature and a detailed clinical analysis.

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.