Visualization of a high protein concentration in the cochlea of a patient with a large endolymphatic duct and sac, using three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging

Association of audiovestibular findings with fluid-attenuated inversion recovery magnetic resonance imaging in patients with vestibular schwannoma

BACKGROUND

Vestibular schwannoma (VS) is a benign tumor of the vestibular nerve. Flair-attenuated inversion recovery (FLAIR) of magnetic resonance imaging (MRI) images are sensitive in detecting high protein contents of fluids.

OBJECTIVES

To investigate the association between signal intensity (SI) on FLAIR images and audiovestibular findings in patients with VS.

METHODS

Medical records of twenty-five patients with VS were retrospectively analyzed.

RESULTS

Larger tumors were associated with increased FLAIR SI of the cochlea, vestibule, and semicircular canal (SCC) on the affected side compared to those of the unaffected side. Pure-tone audiometry (PTA), and speech audiometry were associated with the SI of the affected cochlea. There was no significant correlation between the SI of the vestibule and vestibular evoked myogenic potential, SI of the SCC, and caloric test or video head impulse test results.

CONCLUSION

Our study suggests that tumor size was significantly associated with high SI on FLAIR imaging, and audiological findings were associated with the SI of the affected cochlea. Further studies with larger cohorts are required to confirm the association between vestibular function and FLAIR imaging in VS.

3 Tesla MR imaging of the large endolymphatic duct and sac anomaly with audiological correlation

PURPOSE

Large endolymphatic duct and sac (LEDS) is one of the most common imaging abnormalities in congenital sensorineural hearing loss and is frequently seen with coexistent cochlear anomalies, especially incomplete partition type II. However, MRI findings of accompanying cochlear and especially modiolar dysplasias may be subtle. The purpose of this study is to evaluate the imaging findings of LEDS with high-resolution imaging at 3 T and correlate with the audiological data.

METHODS

3 T temporal bone MRIs of 54 ears in 30 LEDS patients were retrospectively evaluated. The cochlear dysmorphism and modiolar deficiency were assessed qualitatively and quantitatively. The severity of LEDS anomaly, the signal changes within the LEDS and cochlea were also noted. The imaging findings were correlated to the audiological data.

RESULTS

The cochlea was abnormal in 77.8% of the ears with an isolated modiolar deficiency in 11.1%. Cochlea and modiolus were completely normal in 11.1% of the ears. In 63% of the ears X-distance was increased. T2 hypointensity within LEDS and cochlea were detected in 42.6%, and 7.4% of the ears, respectively. The median diameters of LEDS were higher in ears with severe to profound HL than ears with normal to moderate HL (p < 0.05). The X-distance, presence of T2 hypointensity within LEDS, and diameters of modiolus did not show statistical correlation with the audiographic data.

CONCLUSION

High-resolution 3 T imaging of patients with LEDS anomaly revealed a spectrum of cochlear anomalies, but up to 11.1% of the ears had no underlying anomaly despite severe (endolymphatic duct/sac) dilatation and/or profound HL.

Significance of high signal intensity in the endolymphatic duct on magnetic resonance imaging in ears with otological disorders

BACKGROUND

High signal intensity in the endolymphatic duct (ED) is occasionally observed on magnetic resonance imaging (MRI) in ears that have otological disorders.

OBJECTIVE

The signal intensity (SI) in the ED on post-contrast MRI was investigated in subjects with various otological disorders, and the meaning of high SI in the ED was evaluated.

MATERIAL AND METHODS

392 patients with otological disorders and 21 controls without otological symptoms underwent 3 T MRI. The SIs of the ED and the cerebellum were measured, the SI ratio (SIR) was calculated, and ears with SIR ≥4 were identified.

RESULTS

A high SIR was identified in the ED of 3.7% of ears affected by definite Meniere's disease (dMD), 100% of ears affected by large vestibular aqueduct syndrome (LVAS), and 7.1% of ears with no otological symptoms. On the whole, a significant relationship was found between the existence of vestibular or cochlear EH and the SIR in the ED.

CONCLUSION

The MRI finding of high SI in the ED may indicate the mechanism of inner ear disturbances in ears with otological disorders, especially in those with LVAS, and it may suggest an underlying disorder in some ears in which otological symptoms are not apparent.

Sensorineural hearing loss in patients with vestibular schwannoma correlates with the presence of utricular hydrops as diagnosed on heavily T2-weighted MRI

PURPOSE

The purpose of this study was to assess whether the volume of the vestibular endolymphatic space correlates with the degree of hearing loss using heavily T2-weighted fast imaging employing steady-state acquisition with cycle phase (FIESTA-C) MRI.

MATERIALS AND METHODS

A total of 23 patients with vestibular schwannoma, as diagnosed on typical image findings, who underwent FIESTA-C MRI were included. There were 13 women and 10 men with a mean age of 63.5±9.3 (SD) years (range: 49-88years). Two radiologists independently evaluated the volume of the utricle and saccule. Correlation between tumor volume, vestibular endolymphatic space volume and degree of hearing loss - as evaluated with the levels of pure-tone average and speech recognition threshold - were searched for.

RESULTS

The mean saccular, utricular and tumor volumes were 3.17±1.1 (SD) mm³ (range: 1.45-5.7mm³), 14.55±5 (SD) mm³; (range: 6.6-23.9mm³) and 17.4±5.5 (SD) mm³; (range: 8.3-25.4mm³), respectively. There was a moderate correlation between the volume of the utricle and the degree of hearing loss as evaluated with the levels of pure-tone average (rho=0.5; P=0.015) and speech recognition threshold (rho=0.58; P=0.004). There were no significant correlations between saccular and tumor volumes and the degree of hearing loss.

CONCLUSION

The volume of the utricle in patients with obstructive vestibular schwannoma moderately correlates with the degree of hearing loss.

Composition of the Endolymphatic Sac Luminal Fluid in a Patient with Mondini Dysplasia

Objectives

We determined the chemical composition of the human endolymphatic sac luminal fluid in a patient with Mondini dysplasia.

Methods

Four milliliters of endolymphatic sac luminal fluid was sampled in a 41-year-old patient who presented with bilateral Mondini dysplasia and underwent auditory brain stem implantation. Ion and protein concentrations, as well as the osmolarity of the fluid, were analyzed by means of biochemical automated procedures.

Results

The sodium, potassium, and protein concentrations and the osmolarity of the sample were 87 mmol/L, 24 mmol/L, 33.5 g/L, and 258 mOsm/L, respectively.

Conclusions

The composition of the endolymphatic sac luminal fluid found in our patient was similar to that determined in guinea pigs under physiological conditions, and very different from the usual composition of the cochleovestibular endolymph. Contamination of the cochleovestibular endolymphatic compartment by this sodium-rich, potassium-poor, and hypo-osmotic fluid might impair cochleovestibular function by altering the chemical composition of the cochleovestibular endolymph.

Post traumatic deafness: a pictorial review of CT and MRI findings

Hearing loss is a common functional disorder after trauma, and radiologists should be aware of the ossicular, labyrinthine or brain lesions that may be responsible. After a trauma, use of a systematic approach to explore the main functional components of auditory pathways is essential. Conductive hearing loss is caused by the disruption of the conductive chain, which may be due to ossicular luxation or fracture. This pictorial review firstly describes the normal 2-D and 3-D anatomy of the ossicular chain, including the incudo-malleolar and incudo-stapedial joints. The role of 3-D CT in the post-traumatic evaluation of injury to the temporal bone is then evaluated. In the case of sensorineural hearing loss, CT can detect pneumolabyrinth and signs of perilymphatic fistulae but fails to detect subtle lesions within the inner ear, such as labyrinthine haemorrhage or localized brain axonal damage along central auditory pathways. The role that MRI with 3-D-FLAIR acquisition plays in the detection of inner ear haemorrhage and post-traumatic lesions of the brain parenchyma that may lead to auditory agnosia is also discussed.

KEY POINTS

• The most common middle ear injuries are incudo-malleolar and incudo-stapedial joint luxation. • In patients with SNHL, CT can detect pneumolabyrinth or perilymphatic fistula • 3-D-FLAIR MRI appears the best sequence to highlight labyrinthine haemorrhage • Axonal damage and brain hematoma may lead to deafness.

Clinical significance of an increased cochlear 3D fluid-attenuated inversion recovery signal intensity on an MR imaging examination in patients with acoustic neuroma

BACKGROUND AND PURPOSE

The increased cochlear signal on FLAIR images in patients with acoustic neuroma is explained by an increased concentration of protein in the perilymphatic space. However, there is still debate whether there is a correlation between the increased cochlear FLAIR signal and the degree of hearing disturbance in patients with acoustic neuroma. Our aim was to investigate the clinical significance of an increased cochlear 3D FLAIR signal in patients with acoustic neuroma according to acoustic neuroma extent in a large patient cohort.

MATERIALS AND METHODS

This retrospective study enrolled 102 patients with acoustic neuroma, who were divided into 2 groups based on tumor location; 22 tumors were confined to the internal auditory canal and 80 extended to the cerebellopontine angle cistern. Pure tone audiometry results and hearing symptoms were obtained from medical records. The relative signal intensity of the entire cochlea to the corresponding brain stem was calculated by placing regions of interest on 3D FLAIR images. Statistical analysis was performed to compare the cochlear relative signal intensity between the internal auditory canal acoustic neuroma and the cerebellopontine angle acoustic neuroma. The correlation between the cochlear relative signal intensity and the presence of hearing symptoms or the pure tone audiometry results was investigated.

RESULTS

The internal auditory canal acoustic neuroma cochlea had a significantly lower relative signal intensity than the cerebellopontine angle acoustic neuroma cochlea (0.42±0.15 versus 0.60±0.17, P<.001). The relative signal intensity correlated with the audiometric findings in patients with internal auditory canal acoustic neuroma (r=0.471, P=.027) but not in patients with cerebellopontine angle acoustic neuroma (P=.427). Neither internal auditory canal acoustic neuroma nor cerebellopontine angle acoustic neuroma showed significant relative signal intensity differences, regardless of the presence of hearing symptoms (P>.5).

CONCLUSIONS

The cochlear signal on FLAIR images may be an additional parameter to use when monitoring the degree of functional impairment during follow-up of patients with small acoustic neuromas confined to the internal auditory canals.

Enlarged vestibular aqueduct in congenital non-syndromic sensorineural hearing loss in egypt

To estimate the frequency of isolated enlarged vestibular aqueduct (EVA) in patients with non-syndromic sensorineural hearing loss (SNHL) in an Egyptian population sample and to correlate its size with the degree of hearing loss. The study group comprised 16 patients (32 ears) suffering from non-syndromic SNHL since childhood. After a complete basic audiological evaluation, all patients were submitted to non contrast CT scan of the petrous bone in both axial & coronal planes. Vestibular aqueduct (VA) was measured at two points (midpoint & operculum) on right & left sides. The study group was divided according to VA size into three groups: group A, B and C. Group A included 6 ears (4 patients) with EVA, group B included 11 ears (7 patients) with borderline EVA and group C included 15 ears (9 patients) with normal VA size. There were no statistically significant differences between the three groups as regards laterality, degree of hearing loss and audiometric configuration. There was no correlation between VA midpoint & operculum and different variables (age and average pure tone thresholds). However, a significant correlation between VA midpoint & operculum was found. EVA was diagnosed in 6 out of 32 ears (18.75%) in the study sample. EVA size was not related to the degree of hearing loss or configuration. Despite the insignificant findings, moderate and high frequency sloping SNHL were considered the most common findings seen in patients with EVA.

Comparison of contrast effect on the cochlear perilymph after intratympanic and intravenous gadolinium injection

BACKGROUND AND PURPOSE

3D-FLAIR imaging 24 hours after intratympanic gadolinium injection (IT-method) or 4 hours after IV injection (IV-method) has been used to visualize the endolymphatic hydrops in Ménière disease. The purpose of this study was to compare the degree of perilymph enhancement with the 2 methods and the perilymph contrast-effect difference with the IV-method in both sides in patients with unilateral Ménière disease.

MATERIALS AND METHODS

Sixty-one patients with Ménière disease or sudden SNHL were included in this study. Thirty-nine patients who underwent the unilateral IT-method (Gd-DTPA was diluted 8-fold with saline) and 22 patients who underwent the IV-method (a double-dose of Gd-HP-DO3A; 0.4 mL/kg body weight [ie, 0.2 mmol/kg body weight]) at 3T were analyzed retrospectively. Regions of interest of the cochlear perilymph and the medulla oblongata were determined on each image, and the signal-intensity ratio between the 2 (CM ratio) was subsequently evaluated. The differences in the CM ratio between the 2 methods (Student t test) and the IV-method CM ratio between the affected and unaffected sides in patients with unilateral Ménière disease (paired t test) were evaluated.

RESULTS

The IT-method CM ratio (2.98 ± 1.15, n = 39) was higher than the IV-method CM ratio (1.61 ± 0.60, n = 44; P < .001). In patients with unilateral Ménière disease who underwent the IV-method (n = 9), the CM ratio of the affected side (1.86 ± 0.74) was higher than that of the unaffected side (1.29 ± 0.31, P < .05).

CONCLUSIONS

In general, the IT-method provides higher perilymph enhancement than the IV-method. In the patients with unilateral Ménière disease who underwent the IV-method, the affected side had a higher contrast effect.

Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging in sudden sensorineural hearing loss: correlations with audiologic and vestibular testing

OBJECTIVE

Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) has recently been applied to the inner ear, but the relationship between 3D-FLAIR findings and audiovestibular function has been unclear in patients with sudden sensorineural hearing loss (SSNHL). We therefore used 3D-FLAIR MRI to investigate vestibular lesions in patients with SSNHL and determined the correlation between these radiologic findings and results of audiovestibular function tests.

STUDY DESIGN

Prospective study.

METHODS

We enrolled 35 patients who presented with SSNHL from 2008 to 2009. Before treatment, all patients underwent audiovestibular evaluation including pure tone audiometry, electronystagmography, subjective visual vertical, subjective visual horizontal, vestibular evoked myogenic potential, and caloric tests. Pathologic conditions of the inner ears were evaluated by 3D-FLAIR at 3 Tesla, with and without gadolinium enhancement.

RESULTS

Of the 35 patients with SSNHL, 12 (34.3%) showed high signals in the affected inner ear on precontrast 3D-FLAIR MRI. Rates of abnormal results on all vestibular function tests were significantly higher for patients with vestibular lesions than those without vestibular lesions on FLAIR (p < 0.05). Vestibular lesions significantly correlated with the presence of vertigo (relative risk, 3.857; 95% confidence interval, 2.039-7.297) and occurrence of vestibular dysfunction (p < 0.05). There was a significant negative correlation between hearing recovery and positive findings on FLAIR (relative risk, -0.475; 95% confidence interval, -0.698 to -0.175; p = 0.004).

CONCLUSION

High signals in the affected inner ear on 3D-FLAIR MRI closely correlate with vestibular dysfunction and poor hearing recovery in patients with SSNHL, especially when the vestibular apparatus is involved.

MR diagnosis of facial neuritis: diagnostic performance of contrast-enhanced 3D-FLAIR technique compared with contrast-enhanced 3D-T1-fast-field echo with fat suppression

BACKGROUND AND PURPOSE

Current MRI with the CE T1-weighted sequence plays a limited role in the evaluation of facial neuritis due to prominent normal facial nerve enhancement. Our purpose was to retrospectively investigate the usefulness of the CE 3D-FLAIR sequence compared with the CE 3D-T1-FFE sequence in facial neuritis patients.

MATERIALS AND METHODS

We assessed 36 consecutive patients who underwent temporal bone MR imaging at 3T for idiopathic facial palsy. Two readers independently reviewed CE 3D-T1-FFE and CE 3D-FLAIR images to determine the degree of enhancement in each of 5 segments of the facial nerve. We compared AUCs using the Z-test, compared diagnostic performance of 2 MR techniques with the McNemar test, and evaluated interobserver agreement. The Pearson χ(2) test was used for each segment of the facial nerve.

RESULTS

The AUC of CE 3D-FLAIR (reader 1, 0.754; reader 2, 0.746) was greater than that of CE 3D-T1-FFE (reader 1, 0.624; reader 2, 0.640; P < .001). The diagnostic sensitivities, specificities, and accuracies were 97.2%, 86.1%, and 91.7%, respectively, for CE 3D-FLAIR, and 100%, 56.9%, and 78.5%, respectively, for CE 3D-T1-FFE. The specificity and accuracy of CE 3D-FLAIR were greater than those of CE 3D-T1-FFE (specificity, P = .029; accuracy, P = .008). The interobserver agreements for CE 3D-FLAIR (κ-value, 0.831) and CE 3D-T1-FFE (κ-value, 0.694) were excellent. Enhancement of the canalicular and anterior genu segments on CE 3D-FLAIR were significantly correlated with the occurrence of facial neuritis (P < .001 for canalicular; P = .032 and 0.020 for anterior genu by reader 1 and reader 2, respectively).

CONCLUSIONS

CE 3D-FLAIR can improve the specificity and overall accuracy of MR imaging in patients with idiopathic facial palsy.

Physiopathology of the cochlear microcirculation

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature.

Hemorrhage in the endolymphatic sac: a cause of hearing fluctuation in enlarged vestibular aqueduct

OBJECTIVE

Most of the patients with enlarged vestibular aqueduct (EVA) experience sudden hearing deterioration, but the exact mechanism is unclear. We analyzed magnetic resonance (MR) images and the cellular components of endolymph obtained from the endolymphatic sac in patients with EVA, in order to demonstrate the cause of sudden hearing loss.

METHODS

A total of 25 patients (50 ears) with EVA, who had severe to profound hearing loss, were included in this retrospective clinical study. MR examinations were performed by a 3.0-T MR system using an 8-channel sensitivity-encoding head coil. We analyzed endolymphatic fluid harvested from the endolymphatic sac during cochlear implantations in four patients.

RESULTS

The area of low signal intensity in the endolymphatic sac was observed on T2-weighted MR images for 15 of 50 ears. This area was observed more frequently in patients who experienced recent sudden hearing loss (10/12, 83%) than those with stable hearing (5/38, 13%)(Fisher's exact test, p<0.001). In addition, this area showed high signal intensity on fluid attenuated inversion recovery images. Cytologic analysis of the aspirated endolymph from the endolymphatic sac in the patients with this area revealed many erythrocytes.

CONCLUSION

Our data suggests that hemorrhage in the endolymphatic sac could be a cause of sudden hearing deterioration in patients with EVA.

Albumin-like protein is the major protein constituent of luminal fluid in the human endolymphatic sac

The endolymphatic sac (ES) is an inner ear organ that is connected to the cochleo-vestibular system through the endolymphatic duct. The luminal fluid of the ES contains a much higher concentration of proteins than any other compartment of the inner ear. This high protein concentration likely contributes to inner ear fluid volume regulation by creating an osmotic gradient between the ES lumen and the interstitial fluid. We characterized the protein profile of the ES luminal fluid of patients (n = 11) with enlarged vestibular aqueducts (EVA) by proteomics. In addition, we investigated differences in the protein profiles between patients with recent hearing deterioration and patients without hearing deterioration. The mean total protein concentration of the luminal fluid was 554.7±94.6 mg/dl. A total of 58 out of 517 spots detected by 2-DE were analyzed by MALDI-TOF MS. The protein profile of the luminal fluid was different from the profile of plasma. Proteins identified from 29 of the spots were also present in the MARC-filtered human plasma; however, the proteins identified from the other 25 spots were not detected in the MARC-filtered human plasma. The most abundant protein in the luminal fluid was albumin-like proteins, but most of them were not detected in MARC-filtered human plasma. The concentration of albumin-like proteins was higher in samples from patients without recent hearing deterioration than in patients with recent hearing deterioration. Consequently, the protein of ES luminal fluid is likely to be originated from both the plasma and the inner ear and considering that inner ear fluid volumes increase abnormally in patients with EVA following recent hearing deterioration, it is tempting to speculate that albumin-like proteins may be involved in the regulation of inner ear fluid volume through creation of an osmotic gradient during pathological conditions such as endolymphatic hydrops.

Signal alteration of the cochlear perilymph on 3 different sequences after intratympanic Gd-DTPA administration at 3 tesla: comparison of 3D-FLAIR, 3D-T1-weighted imaging, and 3D-CISS

PURPOSE

Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging after intratympanic gadolinium injection is useful for pathophysiologic and morphologic analysis of the inner ear. However, statistical analysis of differences in inner ear signal intensity among 3D-FLAIR and other sequences has not been reported. We evaluated the signal intensity of cochlear fluid on each of 3D-FLAIR, 3D-T(1)-weighted imaging (T(1)WI), and 3D-constructive interference in the steady state (CISS) to clarify the differences in contrast effect among these 3 sequences using intratympanic gadolinium injection.

METHODS

Twenty-one patients underwent 3D-FLAIR, 3D-T(1)WI, and 3D-CISS imaging at 3 tesla 24 hours after intratympanic injection of gadolinium. We determined regions of interest of the cochleae (C) and medulla oblongata (M) on each image, evaluated the signal intensity ratio between C and M (CM ratio), and determined the ratio of cochlear signal intensity of the injected side to that of the non-injected side (contrast value).

RESULTS

The CM ratio of the injected side (3.00+/-1.31, range, 0.53 to 4.88, on 3D-FLAIR; 0.83+/-0.30, range, 0.36 to 1.58 on 3D-T(1)WI) was significantly higher than that of the non-injected side (0.52+/-0.14, range, 0.30 to 0.76 on 3D-FLAIR; 0.49+/-0.11, range, 0.30 to 0.71 on 3D-T(1)WI) on 3D-FLAIR and 3D-T(1)WI (P<0.001), although no significant difference was observed on 3D-CISS (10.03+/-2.19, range, 5.19 to 14.98, on the injected side; 9.52+/-1.63 range, 7.48 to 13.48, on the non-injected side) (P=0.11). The mean contrast value on 3D-FLAIR (5.93+/-2.57, range, 1.22 to 11.05) was significantly higher than that on 3D-T(1)WI (1.73+/-0.60, range, 0.98 to 3.09) (P<0.001).

CONCLUSION

The 3D-FLAIR sequence is the most sensitive for observing alteration in inner ear fluid signal after intratympanic gadolinium injection. Our results warrant use of 3D-FLAIR as a sensitive imaging technique to clarify the pathological and morphological mechanisms of disorders of the inner ear.

Estimation of gadolinium-induced T1-shortening with measurement of simple signal intensity ratio between the cochlea and brain parenchyma on 3D-FLAIR: correlation with T1 measurement by TI scout sequence

PURPOSE

T(1)-shortening of labyrinthine fluid on 3-dimensional fluid-attenuated inversion recovery (3D-FLAIR) has been reported in many inner ear disorders. Although semi-quantitative assessment by simple signal intensity ratio between cochlear fluid and brain tissue has been tried, its feasibility using a multi-channel phased-array head coil with an inherently inhomogenous sensitivity distribution has not been fully evaluated. We evaluated the feasibility of measuring simple signal intensity ratio by correlating rapid T(1) measurements using an inversion time (TI) scout sequence.

MATERIALS AND METHODS

We evaluated 10 patients with Meniere's disease and 4 patients with sudden deafness. Nine of the patients with Meniere's disease received a unilateral intratympanic injection of Gd-DTPA; the tenth patient received bilateral injections. The 4 patients with sudden deafness received a double-dose intravenous injection. Magnetic resonance (MR) images were obtained 24 hours after intratympanic injections and 4 hours after intravenous injections at 3 tesla using a 32-channel head coil. We measured the ratio (CM ratio) between the signal intensity of the perilymph in the cochlea (C) and that of the medulla oblongata (M) and correlated it with the null-point inversion time (TI(null)) obtained with the TI scout sequence. The TI scout consisted of 85 images obtained with TI values between 132.5 and 3087.5 ms at increments of 37.5 ms.

RESULTS

The correlation coefficient between TI(null) and the natural logarithm of the CM ratio was -0.88 (P<0.01). There was significant negative linear correlation.

CONCLUSIONS

Measurement of the simple signal intensity ratio between the cochlea and the medulla can be used for semi-quantitative analysis of 3D-FLAIR. The results of this study may facilitate clinical research of inner-ear disease using 3D-FLAIR.

Increased signal intensity of the cochlea on pre- and post-contrast enhanced 3D-FLAIR in patients with vestibular schwannoma

INTRODUCTION

In the vestibular schwannoma patients, the pathophysiologic mechanism of inner ear involvement is still unclear. We investigated the status of the cochleae in patients with vestibular schwannoma by evaluating the signal intensity of cochlear fluid on pre- and post-contrast enhanced thin section three-dimensional fluid-attenuated inversion recovery (3D-FLAIR).

METHODS

Twenty-eight patients were retrospectively analyzed. Post-contrast images were obtained in 18 patients, and 20 patients had the records of their pure-tone audiometry. Regions of interest of both cochleae (C) and of the medulla oblongata (M) were determined on 3D-FLAIR images by referring to 3D heavily T2-weighted images on a workstation. The signal intensity ratio between C and M on the 3D-FLAIR images (CM ratio) was then evaluated. In addition, correlation between the CM ratio and the hearing level was also evaluated.

RESULTS

The CM ratio of the affected side was significantly higher than that of the unaffected side (rho < 0.001). In the affected side, post-contrast signal elevation was observed (rho < 0.005). In 13 patients (26 cochleae) who underwent both gadolinium injection and the pure-tone audiometry, the post-contrast CM ratio correlated with hearing level (rho < 0.05).

CONCLUSION

The results of the present study suggest that alteration of cochlear fluid composition and increased permeability of the blood-labyrinthine barrier exist in the affected side in patients with vestibular schwannoma. Furthermore, although weak, positive correlation between post-contrast cochlear signal intensity on 3D-FLAIR and hearing level warrants further study to clarify the relationship between 3D-FLAIR findings and prognosis of hearing preservation surgery.

Signal intensity change of the labyrinth in patients with surgically confirmed or radiologically diagnosed vestibular schwannoma on isotropic 3D fluid-attenuated inversion recovery MR imaging at 3 T

OBJECTIVE

The purpose of this study was to evaluate the signal intensity (SI) change of the labyrinth in patients with vestibular schwannoma on isotropic 3D fluid-attenuated inversion recovery (FLAIR) imaging at 3 T.

METHODS

Thirty-four patients with surgically confirmed or radiologically diagnosed vestibular schwannoma were included in this study. Retrospectively, we visually and quantitatively compared the SIs of the cochlea and vestibule on the affected side with those on the unaffected side. We also investigated whether there was correlation between the SI ratios (SIRs) of the labyrinth and the audiometric findings.

RESULTS

On 3D FLAIR images, the SI of the cochlea and vestibule on the affected side was significantly increased in 97% (33/34) and 91% (31/34), respectively. While the SI of the cochlea was diffusely increased, that of the vestibule was only partially increased. Quantitative study also revealed statistically significantly higher SIRs of the cochlea (0.99 +/- 0.29) and vestibule (0.73 +/- 0.31) on the affected side, compared with the cochlea (0.47 +/- 0.20) and vestibule (0.19 +/- 0.10) on the unaffected side. There was no significant correlation of the SIRs of the labyrinth with the degree of hearing loss.

CONCLUSION

In patients with vestibular schwannoma, isotropic 3D FLAIR imaging is a useful method for the evaluation of the SI changes of the labyrinth.

Imaging endolymphatic hydrops at 3 tesla using 3D-FLAIR with intratympanic Gd-DTPA administration

PURPOSE

Visualization of endolymphatic hydrops by 3-dimensional fluid-attenuated inversion recovery-FLAIR using conventional turbo-spin-echo (3D-FLAIR-CONV) after intratympanic injection of Gd-DTPA has been reported in patients with Ménière's disease. Compared to 3D-FLAIR-CONV used in previous studies, the addition of a variable flip-angle technique (3D-FLAIR-VFL) enables very long echo trains and, therefore, shorter scan times. We evaluated whether 3D-FLAIR-VFL could replace 3D-FLAIR-CONV in detecting endolymphatic hydrops after intratympanic Gd-DTPA administration.

METHODS

Eleven patients were included in this study. Twenty-four hours after Gd-DTPA injection, we performed 3D-FLAIR-CONV and 3D-FLAIR-VFL imaging at 3T. We compared the contrast-to-noise ratio (CNR) between cochlear fluid and the cerebellum between the 2 FLAIR sequences. We subjectively scored the size of the endolymphatic space in the cochlea and vestibule for each patient and correlated the scores with the clinical diagnoses.

RESULTS

The CNR of 3D-FLAIR-CONV was significantly higher than that of 3D-FLAIR-VFL. Scores for the size of endolymphatic space in the vestibule were identical between the 2 sequences; however, those in the cochlea disagreed in 3 cases. 3D-FLAIR-CONV correlated better with the clinical diagnoses.

CONCLUSIONS

Currently, we may not be able to replace 3D-FLAIR-CONV with 3D-FLAIR-VFL, at least not with the scanning parameters used in the present study.

Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging findings and prognosis in sudden sensorineural hearing loss

OBJECTIVES/HYPOTHESIS

Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) has recently been developed to detect high concentrations of protein or hemorrhage. We have previously reported that 50% of patients with sudden sensorineural hearing loss (SNHL) show high signals in the affected inner ear on 3D-FLAIR MRI. However, the relationship between 3D-FLAIR findings and hearing prognosis is unclear. Our objective was to evaluate the relationship between the results of 3D-FLAIR MRI at 3 Tesla and prognosis in sudden SNHL.

STUDY DESIGN AND METHODS

We used 3D-FLAIR at 3 Tesla with and without gadolinium enhancement to evaluate the pathologic conditions in the inner ears of 48 patients with sudden SNHL.

RESULTS

Thirty-one of 48 patients with sudden SNHL showed high signals in the affected inner ear on precontrast 3D-FLAIR. Hearing improvement in patients with high signals in the affected inner ear on precontrast 3D-FLAIR (25 +/- 19 dB) was significantly worse than that in patients with no signal (45 +/- 27 dB; P < .05). Our analysis suggests that high signals in the affected inner ear on precontrast 3D-FLAIR MRI is a new prognostic factor for sudden SNHL.

CONCLUSIONS

3D-FLAIR findings show that high signals in the cochlea on precontrast 3D-FLAIR are related to a poor hearing prognosis. These signals may reflect minor hemorrhage or an increased concentration of protein in the inner ear, which has passed through blood vessels with increased permeability or has originated in disrupted cells in the inner ear.

Síndrome do aqueduto vestibular alargado: uma causa de disacusia neurossensorial

TEMA: a síndrome do aqueduto vestibular alargado (SAVA) é caracterizada pelo alargamento do aqueduto vestibular associada a disacusia. O grau da perda auditiva é variável, podendo ser flutuante, progressiva ou súbita. Sintomas vestibulares podem estar presentes. O diagnóstico é realizado por exames de imagem. OBJETIVO: relatar um caso de SAVA. MÉTODO: lactente, gênero feminino, realizou tomografia computadorizada de ouvidos e exames de audição. RESULTADO: constatou-se alargamento do aqueduto vestibular maior que 1,5mm de diâmetro e perda auditiva neurossensorial à direita. CONCLUSÃO: com a avaliação auditiva precoce é possível o diagnóstico da disacusia, mesmo em crianças com disacusias unilaterais. Embora a literatura consultada mostre que o diagnóstico da SAVA ocorra tardiamente, no presente caso, o diagnóstico etiológico foi possibilitado pela tomografia computadorizada.

Increased cochlear fluid-attenuated inversion recovery signal in patients with vestibular schwannoma

BACKGROUND AND PURPOSE

Elevated protein levels have been reported in perilymph of patients with vestibular schwannoma. Fluid-attenuated inversion recovery (FLAIR) imaging is sensitive to high protein contents in fluids. The purpose of this study was to investigate if in patients with unilateral vestibular schwannoma, cochlear FLAIR signal intensity on the affected side is increased compared with the unaffected side and control subjects.

MATERIALS AND METHODS

Fifteen patients with unilateral vestibular schwannoma and 25 age-matched control subjects (without a history of hearing loss) were retrospectively evaluated. All patients and controls had routine 5-mm FLAIR and T1- and T2-weighted imaging of the brain. The signal intensity of both cochleae was evaluated by placing a small region of interest on FLAIR images. The signal intensity of the brain stem was also determined by placing a second region of interest. A ratio of cochlear signal intensity to brain stem signal intensity (CIBI ratio) was determined. A t test was used to compare the CIBI ratios.

RESULTS

In patients, the mean CIBI ratio of the affected side was 0.89 +/- 0.18, and that of the unaffected side was 0.57 +/- 0.12. In control subjects, it was 0.51 +/- 0.07. The CIBI ratio of the affected side was significantly higher compared with the unaffected side (P < .001) and compared with control subjects (P < .001).

CONCLUSION

Patients with vestibular schwannoma have increased cochlear FLAIR signal intensity on the affected side compared with the unaffected side and healthy subjects.