Inner Ear Enhancement With Delayed 3D-FLAIR MRI Imaging in Vestibular Schwannoma

Four-hour-delayed 3D-FLAIR MRIs in patients with acute unilateral peripheral vestibulopathy

OBJECTIVE

Conventionally, MRI aids in differentiating acute unilateral peripheral vestibulopathy/vestibular neuritis (AUPV/VN) from mimickers. Meanwhile, the diagnostic utility of MRIs dedicated to the inner ear remains to be elucidated for diagnosing AUPV/VN.

METHODS

We prospectively recruited 53 patients with AUPV/VN (mean age ± SD = 60 ± 15 years, 29 men). Initial MRIs were performed with a standard protocol, and an additional axial 3D-fluid-attenuated inversion recovery (3D-FLAIR) sequence was obtained 4 h after intravenous injection of gadoterate meglumine. Abnormal enhancement was defined as a signal intensity that exceeded the mean + 2SD value on the healthy side. The findings of neurotologic evaluation and MRIs were compared.

RESULTS

Overall, the inter-rater agreement for gadolinium enhancement was 0.886 (Cohen's kappa coefficient). Enhancement was observed in 26 patients (49%), most frequently in the vestibule (n = 20), followed by the anterior (n = 12), horizontal (HC, n = 8), posterior canal (n = 5), and superior (n = 3) and inferior (n = 1) vestibular nerves. In multivariable logistic regression analysis, the enhancement was associated with decreased HC gain in video head-impulse tests (p = 0.036), increased interaural difference in ocular vestibular-evoked myogenic potentials (p = 0.001), and a longer onset-to-MRI time span (p = 0.024). The sensitivity and specificity were 92.3% and 81.5%, respectively, with an area under the curve of 0.90 for predicting gadolinium enhancement.

INTERPRETATION

Robust gadolinium enhancement was observed on 4-hour-delayed 3D-FLAIR images in nearly half of the patients with AUPV/VN, with a good correlation with the results of neurotologic evaluation. The positivity may be determined by the extent of vestibular deficit, timing of imaging acquisition, and possibly by the underlying etiology causing AUPV/VN. MRIs may aid in delineating the involved structures in AUPV/VN.

Peritumoral Signal on Postcontrast FLAIR Images: Description and Proposed Biomechanism in Vestibular Schwannomas

BACKGROUND AND PURPOSE

Anecdotally, postcontrast FLAIR images of vestibular schwannomas can show peritumoral hyperintense signal, hypothesized to represent gadolinium extravasation. This study assessed the incidence of this phenomenon in a cohort of patients with treatment-naïve sporadic vestibular schwannomas.

MATERIALS AND METHODS

A retrospective review of 20 patients with presumed vestibular schwannoma based on characteristic imaging findings and with dedicated internal auditory canal imaging, including postcontrast T1W1 and postcontrast FLAIR, was performed. Tumor size and location were recorded, as was the presence or absence of a fundal fluid cleft. Images were reviewed for the presence of peritumoral hyperintense signal on FLAIR images (a "halo") and for both subjectively and objectively elevated signal in the ipsilateral cochlea and fundus.

RESULTS

Patients were randomly selected from an institutional vestibular schwannoma registry. Eleven (55.0%) were women. A peritumoral halo was present in 90% of patients, averaging 1.0 (SD, 0.2) mm in thickness. The maximum mean FLAIR signal in the ipsilateral fundus (205.9 [SD, 110.2]) was significantly greater than on the contralateral side (121.6 [SD, 27.8]) (P = .02). Maximum mean ipsilateral intracochlear signal (167.8 [SD, 104.5]) was also significantly greater than on the contralateral side (113.4 [SD, 40.1]) (P = .04).

CONCLUSIONS

A peritumoral halo on postcontrast FLAIR images was present in 90% of our cohort with randomly selected, treatment-naïve sporadic vestibular schwannomas. Although its mechanism is unknown, this signal is hypothesized to represent gadolinium extravasation, given an ipsilateral increased signal in the adjacent internal auditory canal fundus and cochlea.

Presbycusis and Hearing Preservation in Observed Vestibular Schwannomas

OBJECTIVE

We reviewed a cohort of patients with untreated sporadic vestibular schwannoma (VS) and examined the relationship between high-frequency hearing loss (HFHL) in the non-VS ear and long-term hearing outcomes in the VS-affected ear. We hypothesized that the progression of HFHL is associated with accelerated hearing decline in sporadic VS.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary center.

PATIENTS

We studied 102 patients with sporadic VS diagnosed from 1999 to 2015 with ≥5 years of observation (median, 6.92; interquartile range, 5.85-9.29). Sixty-six patients had AAO-HNS class A/B hearing at presentation and were included in analysis.

INTERVENTIONS

Audiometry, serial magnetic resonance imaging for observation of VS.

MAIN OUTCOME MEASURES

Four-frequency pure tone average (PTA) and word recognition scores (WRS) in the VS-affected ear. Decline in high-frequency PTA (average of thresholds at 4000, 6000, and 8,000 Hz) was defined as ≥10 dB during the study period. Decline in WRS was defined as ≥10%.

RESULTS

Compared with those without, patients with progressive HFHL in the non-VS ear were more likely to experience a decline in WRS in the VS ear (80% vs. 54%, p = 0.031). However, the same group showed no difference (52% vs. 41%, p = 0.40) in decline in PTA of the VS ear.

CONCLUSIONS

Patients with observed VS who experience progressive HFHL in the non-VS ear are more likely to experience significant declines in speech understanding in the VS-affected ear over time. Patients with a history of presbycusis may have an increased risk of losing serviceable hearing because of sporadic VS.

Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss

OBJECTIVE

To compare the findings of magnetic resonance imaging (MRI) with advanced protocols in patients with various types of acute sensorineural hearing loss (ASNHL).

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Two hundred eighty-seven patients with ASNHL.

INTERVENTIONS

All patients underwent MRI scanning, including heavily T2-weighted three-dimensional fluid-attenuated inversion recovery before and 4 hours after the intravenous administration of gadolinium contrast medium (delayed 3D-FLAIR). A hybrid of the reversed image of the positive endolymph signal and the native image of the perilymph signal image was constructed to visualize the endolymphatic space.

RESULTS

The detection rates of abnormal MRI findings vary significantly among different types of ASNHL. A hyperintense signal on delayed 3D-FLAIR was observed in all patients with intralabyrinthine schwannoma or vestibular schwannoma and 20.5% of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) but was rarely observed in definite Ménière's disease (MD, 2.6%). In contrast, endolymphatic hydrops (EH) was frequently observed in patients with definite MD (79.5%) but was observed much less frequently in patients with ISSNHL (11.0%). In patients with cochlear MD and ALHL, detection rates of cochlear EH were similar to those with definite MD, whereas detection rates of vestibular EH were significantly lower than in patients with definite MD.

CONCLUSIONS

The significantly different detection rates of abnormal MRI findings among various types of ASNHL shed light on the distinct pathophysiology of each disorder. A diagnosis based on MRI findings with advanced protocols may help select treatment strategies and provide prognostic information for patients.

Automated Whole Cochlear T2 Signal Demonstrates Weak Correlation with Hearing Loss in Observed Vestibular Schwannoma

INTRODUCTION

We sought to evaluate the correlation between whole cochlear T2 signal changes obtained with a novel automated segmentation method and hearing levels, both at diagnosis and over time, in patients with observed vestibular schwannoma.

METHODS

This retrospective correlation study within an academic medical center neurotology practice evaluated 127 patients with vestibular schwannoma observed over time, each with ≥2 MRI scans (367 total) and ≥2 audiograms (472 total). 86 patients had T2-weighted sequences with sufficient resolution for cochlear signal analysis, yielding 348 unique timepoint intervals. The main outcome measure was correlation of the ipsilateral-to-contralateral ratio of whole cochlear T2 signal with hearing outcomes as measured by pure tone average (PTA) and word recognition score (WRS).

RESULTS

Whole cochlear T2 signal ratios did not show a correlation with hearing levels at diagnosis. Change in signal ratio over time showed weak correlation with changes in PTA, but not WRS, over time. Cochlear signal ratio did not precede changes in hearing but did follow changes in both PTA and WRS.

CONCLUSION

Whole cochlear T2 signal ratios were weakly correlated with changes in hearing in patients with observed vestibular schwannoma. The technology of automated segmentation and signal processing holds promise for future evaluation of clinical entities causing cochlear signal changes.

Increased Labyrinthine T1 Postgadolinium Signal Intensity Is Associated with the Degree of Ipsilateral Sensorineural Hearing Loss in Patients with Sporadic Vestibular Schwannoma

BACKGROUND AND PURPOSE

Vestibular schwannomas are benign, generally slow-growing tumors, commonly presenting with hearing loss. Alterations in the labyrinthine signal are seen in patients with vestibular schwannoma; however, the association between imaging abnormalities and hearing function remains poorly defined. The purpose of this study was to determine whether labyrinthine signal intensity is associated with hearing in patients with sporadic vestibular schwannoma.

MATERIALS AND METHODS

This was an institutional review board-approved retrospective review of patients from a prospectively maintained vestibular schwannoma registry imaged in 2003-2017. Signal-intensity ratios of the ipsilateral labyrinth were obtained using T1, T2-FLAIR, and postgadolinium T1 sequences. Signal-intensity ratios were compared with tumor volume and audiometric hearing threshold data including pure tone average, word recognition score, and American Academy of Otolaryngology-Head and Neck Surgery hearing class.

RESULTS

One hundred ninety-five patients were analyzed. Ipsilateral labyrinthine signal intensity including postgadolinium T1 images was positively correlated with tumor volume (correlation coefficient = 0.17, P  = .02). Among signal-intensity ratios, postgadolinium T1 was significantly positively associated with pure tone average (correlation coefficient = 0.28, P  < .001) and negatively associated with the word recognition score (correlation coefficient = -0.21, P  = .003). Overall, this result correlated with impaired American Academy of Otolaryngology-Head and Neck Surgery hearing class (P  = .04). Multivariable analysis suggested persistent associations independent of tumor volume with pure tone average (correlation coefficient = 0.25, P  < .001) and the word recognition score (correlation coefficient = -0.17, P  = .02) but not hearing class (P  = .14). No consistent significant associations were noted between noncontrast T1 and T2-FLAIR signal intensities and audiometric testing.

CONCLUSIONS

Increased ipsilateral labyrinthine postgadolinium signal intensity is associated with hearing loss in patients with vestibular schwannoma.

Case report: Concurrent intravestibular schwannoma mimicking Ménière's disease and cochlear hydrops detected via delayed three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging

Objective

To present a case of intralabyrinthine schwannoma (ILS) presenting as Ménière's disease diagnosed via 4-h delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI) and treated successfully using the translabyrinthine approach.

Patient

A patient who was diagnosed with intravestibular ILS.

Interventions

The patient underwent comprehensive preoperative neurological examinations and MRI. The tumor was resected using the translabyrinthine approach and was pathologically confirmed as schwannoma based on the surgical specimen.

Main outcome measures

Preoperative audiogram and vestibular test findings and MRI images.

Results

Preoperatively, pure-tone audiogram showed progressive sensorineural hearing loss only on the affected side. The video head impulse test and vestibular evoked myogenic potential test showed vestibular dysfunction on the affected ear. Immediate gadolinium-enhanced T1-weighted MRI revealed an enhanced region in the vestibule. Meanwhile, magnetic resonance cisternography showed a filling defect. Delayed 3D-FLAIR MRI revealed a signal void in the scala media of the cochlea indicative of cochlear hydrops, and a strong signal in the perilymph at the basal cochlea suggestive of impaired blood–labyrinthine barrier.

Conclusion

Delayed 3D-FLAIR MRI is useful in diagnosing concurrent ILSs and endolymphatic hydrops.

Clinical Value of 3D-FLAIR MRI in Idiopathic Sudden Sensorineural Hearing Loss

BACKGROUND

Three-dimensional fluid-attenuated inversion recovery sequence magnetic resonance imaging (3D-FLAIR MRI) has been used in the diagnosis of inner ear diseases. However, the relevance of 3D-FLAIR MRI appearances with multiple features and prognosis of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) remains unclear.

METHODS

This study was a retrospective trial. We recruited 1300 patients with unilateral ISSNHL hospitalized from May 2017 to January 2019. They were divided into four groups according to their 3D-FLAIR MRI appearances: normal (n = 739), inner ear hemorrhage (n = 218), increased protein content (n = 288), and blood-labyrinth barrier damage (n = 55). The correlation between 3D-FLAIR MRI appearances and the degree or type of deafness of the participants was analyzed.

RESULTS

There was a statistical difference in the deafness side (p < 0.001) and vestibular dysfunction (p < 0.001) among the four groups. There was a statistical difference in the duration of treatment (p < 0.001) and the incidence of dizziness or vertigo (p < 0.001) for patients among these groups. The degree of deafness in the patients in the inner ear hemorrhage group was significantly more severe than that of the patients in the other three groups (p < 0.001).

CONCLUSION

3D-FLAIR MRI appearances were correlated with the prognosis of patients with ISSNHL.

Automatic Segmentation of Intracochlear Anatomy in MR Images Using a Weighted Active Shape Model

There is evidence that cochlear MR signal intensity may be useful in prognosticating the risk of hearing loss after middle cranial fossa (MCF) resection of acoustic neuroma (AN), but the manual segmentation of this structure is difficult and prone to error. This hampers both large-scale retrospective studies and routine clinical use of this information. To address this issue, we present a fully automatic method that permits the segmentation of the intra-cochlear anatomy in MR images, which uses a weighted active shape model we have developed and validated to segment the intra-cochlear anatomy in CT images. We take advantage of a dataset for which both CT and MR images are available to validate our method on 132 ears in 66 high-resolution T2-weighted MR images. Using the CT segmentation as ground truth, we achieve a mean Dice (DSC) value of 0.81 and 0.79 for the scala tympani (ST) and the scala vestibuli (SV), which are the two main intracochlear structures.Clinical Relevance- The proposed method is accurate and fully automated for MR image segmentation. It can be used to support large retrospective studies that explore relations between MR signal in preoperative images and outcomes. It can also facilitate the routine and clinical use of this information.

Four-Hour Delayed Gadolinium-Enhanced 3D-FLAIR MR Imaging Highlights Intralabyrinthine Micro-Schwannomas

OBJECTIVE

To demonstrate the clinical significance of 4-hour delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery (delayed 3D-FLAIR) in patients with intralabyrinthine schwannoma (ILS).

PATIENTS

Three patients who were clinically diagnosed with ILS.

INTERVENTIONS

All patients underwent audiological examinations and magnetic resonance imaging (MRI) scans. The MR-protocol included axial MR cisternography, immediate gadolinium-enhanced T1-weighted sequence, and heavily T2-weighted 3D-FLAIR prior to and 4 hours after the intravenous administration of gadolinium contrast medium.

MAIN OUTCOME MEASURES

All MR images were visually inspected.

RESULTS

In all three patients with ILS, delayed 3D-FLAIR MRI demonstrated a strong signal of cochlear fluid surrounding the tumor, which highlighted a tumor region that lacked signals.

CONCLUSIONS

Delayed 3D-FLAIR MRI may serve as a novel diagnostic tool for the early detection of intralabyrinthine micro-schwannoma. The findings also shed light on the pathophysiology of ILS.

MRI With Gadolinium as a Measure of Blood-Labyrinth Barrier Integrity in Patients With Inner Ear Symptoms: A Scoping Review

Objective: Capillaries within the inner ear form a semi-permeable barrier called the blood-labyrinth barrier that is less permeable than capillary barriers elsewhere within the human body. Dysfunction of the blood-labyrinth barrier has been proposed as a mechanism for several audio-vestibular disorders. There has been interest in using magnetic resonance imaging (MRI) with intravenous gadolinium-based contrast agents (GBCA) as a marker for the integrity of the blood labyrinth barrier in research and clinical settings. This scoping review evaluates the evidence for using intravenous gadolinium-enhanced MRI to assess the permeability of the blood-labyrinth barrier in healthy and diseased ears.

Methods: A systematic search was conducted of three databases: PubMed, EMBASE, CINAHL PLUS. Studies were included that used GBCA to study the inner ear and permeability of the blood-labyrinth barrier. Data was collected on MRI protocols used and inner ear enhancement patterns of healthy and diseased ears in both human and animal studies.

Results: The search yielded 14 studies in animals and 53 studies in humans. In healthy animal and human inner ears, contrast-enhanced MRI demonstrated gradual increase in inner ear signal intensity over time that was limited to the perilymph. Signal intensity peaked at 100 min in rodents and 4 h in humans. Compared to controls, patients with idiopathic sudden sensorineural hearing loss and otosclerosis had increased signal intensity both before and shortly after GBCA injection. In patients with Ménière's disease and vestibular schwannoma, studies reported increased signal at 4 h, compared to controls. Quality assessment of included studies determined that all the studies lacked sample size justification and many lacked adequate control groups or blinded assessors of MRI.

Conclusions: The included studies provided convincing evidence that gadolinium crosses the blood-labyrinth barrier in healthy ears and more rapidly in some diseased ears. The timing of increased signal differs by disease. There was a lack of evidence that these findings indicate general permeability of the blood-labyrinth barrier. Future studies with consistent and rigorous methods are needed to investigate the relationship between gadolinium uptake and assessments of inner ear function and to better determine whether signal enhancement indicates permeability for molecules other than gadolinium.