Visualization Of Endolymphatic Hydrops Research Articles

Interpretation of consensus on MRI of endolymphatic hydrops in patients with suspected hydropic ear disease and domestic research progress

Endolymphatic hydrops（EH） is considered the histological hallmark of Meniere's disease. Visualization of EH has been achieved by special sequences of inner ear magnetic resonance imaging（MRI） with gadolinium-based contrast-agent via intravenous or intratympanic administration. Although it has been applied for more than ten years since 2007, a unified view on this technique has not yet been achieved. In 2022, Yang Jun and Duan Maoli et al led the organization to write the international expert consensus on MRI of EH. This article interprets the main contents and reports related progress.

Consensus on MR Imaging of Endolymphatic Hydrops in Patients With Suspected Hydropic Ear Disease (Meniere).

Endolymphatic hydrops (EH) is considered the histological hallmark of Meniere's disease. Visualization of EH has been achieved by special sequences of inner ear magnetic resonance imaging (MRI) with a gadolinium-based contrast agent via intravenous or intratympanic administration. Although it has been applied for more than 10 years since 2007, a unified view on this technique has not yet been achieved. This paper presents an expert consensus on MRI of endolymphatic hydrops in the following aspects: indications and contra-indications for patient selection, methods of contrast-agent administration (intravenous or intratympanic), MRI sequence selection, the specific scanning parameter settings, and standard image evaluation methods and their advantages and disadvantages. For each part of this consensus, a comment is attached to elucidate the reasons for the recommendation.

Dexamethasone does not affect endolymphatic hydrops (EH) in patients with Meniere's disease within 24 h, and intratympanic administration of gadolinium plus dexamethasone simplifies high-quality imaging of EH using a novel protocol of 7 min

BackgroundIntratympanic administration of gadolinium chelate allows for a better visualization of endolymphatic hydrops (EH) using MRI than intravenous injection and was recently further improved to facilitate high-quality imaging of EH in 7 min. The aim of the present study was to simplify the intratympanic administration protocol by mixing gadolinium chelate with therapeutic dexamethasone and to evaluate the effects of this mixture on the visualization of EH in MRI. Materials and methodsIn an in vitro study, the potential impact of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) on the stability of dexamethasone was evaluated by analyzing dynamic changes in dexamethasone with high-performance liquid chromatography (HPLC) after mixing with Gd-DTPA. Ten patients with definite Meniere's disease (MD) were recruited to study the potential interference of dexamethasone on MRI visualization of EH, and 49 patients with MD were recruited to evaluate the effect of intratympanic injection of Gd-DTPA mixed with dexamethasone on MRI of EH using a 3T MR machine and a novel heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery reconstructed using a magnitude plus zero-filled interpolation (hT2FLAIR-MZFI) sequence. ResultsThe retention times and peak area of dexamethasone in HPLC were not modified by the addition of Gd-DTPA. EH grading in the cochlea and vestibule was not influenced in any ear by intratympanic injection of dexamethasone. Excellent inner ear images were obtained from all patients, and EHs with various grades were displayed. There were significant correlations between diagnosis and cochlear EH (p < 0.01, Spearman's Rho), between diagnosis and vestibular EH (p < 0.01, Spearman's Rho), and between cochlear and vestibular EH (p < 0.01, Spearman's Rho). The distribution of Gd-DTPA plus dexamethasone negatively correlated with the grade of vestibular EH. Injury of the endolymph-perilymph barrier was detected in one cochlea and three vestibules of 59 inner ears with MD. ConclusionsIntratympanic administration of Gd-DTPA plus dexamethasone yielded high-quality MRI images of EH in patients with MD using a novel 7-min protocol and simplified the clinical application. Intratympanic administration of Gd-DTPA plus dexamethasone might be used to test its therapeutic effect in future work. Level of evidence3.

Visualization of Endolymphatic Hydrops in Patients With Unilateral Idiopathic Sudden Sensorineural Hearing Loss With Four Types According to Chinese Criterion.

Objective: The aim of this study is to evaluate the possible value of endolymphatic hydrops (EH) in patients with unilateral idiopathic sudden sensorineural hearing loss (UISSNHL) with four types according to audiometry.Methods: Seventy-two patients (40 men and 32 women; age range, 28–78 years; mean age: 50.0 ± 12.9 years) with UISSNHL were admitted retrospectively into this study. Based on the pure tone audiometry before treatment, the hearing loss of all these patients were categorized into four types: low-frequency group (LF-G), high-frequency group (HF-G), flat group (F-G), and total deafness group (TD-G). The average time from symptom onset to the first examination was 6.9 ± 4.4 days (1–20 days). 3D-FLAIR MRI was performed 24 h after intratympanic injection of gadolinium (Gd) within 1 week after the UISSNHL onset. The incidence of EH in the affected ears based on four types of hearing loss were analyzed using the Chi-square test, and the possible relationship with vertigo and prognosis were also assessed.Results: Eleven of 21 patients (52.4%) in LF-G had the highest EH-positive rate, followed by 18.2% in HF-G, 11.8% in F-G, and 17.4% in TD-G. The significant difference was found in the four groups (P = 0.018). The EH rate of LF-G was statistically significantly higher than that of F-G and TD-G (P = 0.009, P =0.014), respectively. After being valued by the volume-referencing grading system (VR scores), the EH level was represented by the sum scores of EH. In LF-G, no statistically significant difference was found in the prognosis of ISSNHL patients between with the EH group and the no EH group (P = 0.586). The symptom “vertigo” did not correlate with EH and prognosis.Conclusions: EH was observed in UISSNHL patients by 3D-FLAIR MRI. EH may be responsible for the pathology of LF-G but not related to prognosis. It might be meaningless to assess EH in other hearing loss types, which might be more related to the blood-labyrinth dysfunction.

Endolymphatic Hydrops, Evaluated Using 3T MRI in Patients with Clinically Confirmed Meniere Disease

Ménière’s disease (MD) is characterized by intermittent episodes of vertigo with fluctuating sensorineural hearing loss, tinnitus, and aural fullness. Despite numerous studies, the etiology of this disorder remains poorly understood and thus diagnostic criteria are mainly clinical. Development and progress in magnetic resonance imaging (MRI) techniques, in 2007, has enabled visualization of endolymphatic hydrops, which was the milestone achievement. We present two cases of patients with clinically confirmed MD with a set of audiological, otoneurological examinations and MRI performed. Structures of the inner ear were visualized using contrast-enhanced MR imaging after a 4-hour delayed intravenous gadolinium administration. The cochlea and vestibule were evaluated separately and classified using Barath grading scale. Endolymphatic hydrops in the clinically affected ears was confirmed using MRI. Due to disabling and intractable MD, a decision about vestibular neurectomy was made.

Systematic review of magnetic resonance imaging for diagnosis of Meniere disease.

The diagnostic criteria for Meniere Disease (MD) are clinical and include two categories: definite MD and probable MD, based on clinical examination and without the necessity of advanced vestibular or audiological testing. The condition is a heterogeneous disorder and it is associated with endolymphatic hydrops (EH), an accumulation of endolymph in the inner ear that causes damage to the ganglion cells. Patients with suspected EH can be examined by Magnetic Resonance Imaging (MRI), offering new insights into these inner ear disorders. Results of imaging studies using the hydrops protocols show conflicting results in MD patients. These discrepancies can be dependent either on the MRI sequence parameters or on the method of hydrops grading or the inclusion criteria to select patients. The visualization of EH can be classified based on a semi-quantitative ratio between endolymph and perilymph liquids, or on the distinction between the saccule and the utricle structures. In addition, MRI can also be used to evaluate whether cochleovestibular nerves can present with imaging signs of axonal loss.In this systematic review, we have selected case-controlled studies to better characterize the potential added value in the diagnosis and management of patients with MD. Using different techniques, studies have identified the saccule as the most specifically involved structure in MD, and saccular hydrops seems to be associated with low to medium-tone sensorineural hearing loss degree. However, early symptoms still appear too subtle for identification using MRI and the reproducibility of the hydrops protocols with various MRI scan manufacturers is debatable, thus limiting expansion of these techniques into clinical practice for the diagnosis of MD at this time.Further research is needed. The future inclusion of semicircular canal hydrops location in the imaging signs and the application of MRI in patients with atypical presentations hold promise.

大阪大学における General Electric 製 3テスラ MRI 装置を用いた内耳造影撮影

Visualization of endolymphatic hydrops (EH) by magnetic resonance imaging (MRI) is becoming increasingly important and popular for the diagnosis of various inner ear diseases, such as Meniere's disease. However, most studies have been performed using Siemens scanners. At Osaka University, we have been using General Electric (GE) scanners at 3 Tesla for imaging EH since 2007. Both the scanning protocols of 24h after intratympanic administration of gadolinium (Gd) and 4h after intravenous injection of Gd are used. In contrast to the Siemens system, in which MRI sequences specific for EH imaging are available, we use the conventional two-dimensional fluid-attenuated inversion-recovery (2D-FLAIR) and three-dimensional fast imaging sequences employing steady state acquisition (FIESTA, also known as “cisternography”) to acquire axial images of the inner ear of 2-mm and 0.5-mm thickness, respectively. Written informed consent is obtained from the patients before the imagings. The examinations are performed in compliance with the Declaration of Helsinki and are approved by the institutional ethics committee. In total, 76 patients have undergone MRI under various clinical situations, such as before and after sac surgery, and before intratympanic administration of gentamycin to treat Meniere's disease. The presence of hydrops is clearly detected by T2-FLAIR images in most patients with clinical EH. Unlike the MRI sequences obtained using the Siemens system, it is currently difficult to distinguish the area of the inner ear with no enhancement (either perilymph with no contrast or endolymph) from bony areas surrounding the inner ear in our T2-FLAIR images obtained using the GE system. Comparison between T2-FLAIR and FIESTA sections at the same level is recommended. Three-dimensional volumetric co-registration of FIESTA images to T2-FLAIR images is also helpful when the patient's head movements during the MRI scanning are not negligible.

Visualization of endolymphatic hydrops after intratympanic injection of Gd-DTPA: a comparison of high resolution three dimensional-real inversion recovery and three dimensional fluid-attenuated inversion recovery with a variable flip angle sequence

Objective To compare the value of high resolution 3D-real inversion recovery(3D-real IR) and 3D fluid-attenuated inversion recovery with a variable flip angle (3D-Flair-VFL) sequence in the visualization of endolymphatic hydrops. Methods 52 ears in 40 patients with Meniere's disease or delayed endolymphatic hydrops were enrolled and performed by axial 3D-real IR and 3D-Flair MRI scans 24 hours after intratympanic injection of eight-fold diluted Gd-DTPA. Signal to noise ratio (SNR) and contrast-to-noise ratio (CNR) of the two sequences were calculated and compared by t test. Whether there were endolymphatic hydrops in the basal turn, middle turn, apical turn of the cochlear and vestibule was further evaluated. Results Both the SNR and CNR of 3D-real IR images were statistically higher than 3D-Flair images (SNR: 28.06±12.71 vs. 17.64±6.38, P<0.05; CNR: 33.79±13.52 vs. 15.40±6.04, P<0.05). Endolymphatic hydrops of the basal turn, second turn, apical turn of the cochlear and vestibule detected by 3D-Flair-VFL images were 33, 37, 10 and 41 cases, respectively, while by 3D-Flair-VFL images were 46, 46, 46 and 49 cases, respectively. There were significant differences between the two sequences in evaluating basal turn, second turn, apical turn of the cochlear except vestibule (P<0.05). Conclusion 3D-real IR images are clearer than 3D-Flair-VFL images and can display endolymphatic hydrops more precisely. Key words: Magnetic resonance imaging; Ear, inner; Meniere disease

Magnetic Resonance Imaging Evaluation of Endolymphatic Hydrops in Cases With Otosclerosis.

Endolymphatic hydrops (EH) has been reported in cases with otosclerosis, and preoperative EH could be a risk factor for inner ear disturbances after stapes surgery. Visualization of EH has recently become possible using magnetic resonance imaging (MRI) with contrast agents. This study investigated the presence of EH on MRI in ears with clinical otosclerosis. Retrospective case series. University hospital. 27 ears of 15 cases diagnosed with otosclerosis. Ears were evaluated by 3-T MRI performed 4 hours after intravenous injection of gadolinium. The degree of EH in the vestibule and cochlea was classified into three grades (none, mild, and significant). Imaging data were compared with clinical findings for all ears. Imaging and clinical findings. Varying degrees of cochlear EH and vestibular EH were observed in 20 and 15 ears, respectively. Episodes of acute sensorineural hearing loss with rotatory vertigo occurred in four ears that showed severe EH in the cochleae and vestibules. Severe EH, however, was also observed in ears without such symptoms. The presence of EH in ears with otosclerosis was clearly visualized in the present patient series. Such MRI evaluation could provide useful information for managing symptoms related to EH.

Ocular vestibular evoked myogenic potential frequency tuning in certain Menière's disease

Ocular vestibular evoked myogenic potentials (oVEMP) represent extraocular muscle activity in response to vestibular stimulation. To specify the value of oVEMP in the diagnostics of Menière's disease, the amplitude ratio between 500 and 1000 Hz stimuli was investigated.Thirty-nine patients with certain Menière's disease, i.e. definite Menière's disease with visualization of endolymphatic hydrops by magnetic resonance imaging and 19 age-matched healthy controls were enrolled in this study. oVEMP were recorded using 500 and 1000 Hz air-conducted tone bursts. For Menière's ears, the 500/1000 Hz amplitude ratio (mean ratio = 1.20) was significantly smaller when compared to unaffected ears of Menière's patients (mean ratio = 1.80; p = 0.008) or healthy controls (mean ratio = 1.81; p = 0.011). The amplitude ratio was neither correlated with the degree of endolymphatic hydrops nor with the duration of disease. While an older age was associated with a diminished amplitude ratio in healthy controls, there was no correlation between the amplitude ratio and age in Menière's ears. Hence, the calculation of the oVEMP 500/1000 Hz amplitude ratio may be a valuable diagnostic tool for Menière's disease.

Visualization of endolymphatic hydrops with MR imaging in patients with Ménière’s disease and related pathologies: current status of its methods and clinical significance

Ménière's disease is an inner ear disorder characterized by vertigo attacks, fluctuating low-frequency hearing loss, ear fullness, and tinnitus. Endolymphatic hydrops has long been thought to be the pathological basis for Ménière's disease. Some patients have inner ear symptoms that do not match the diagnostic guidelines for Ménière's disease, and these are also thought to be related to endolymphatic hydrops. The diagnosis of endolymphatic hydrops is usually made based on clinical symptoms with some assistance from otological functional tests. Recently, the objective diagnosis of endolymphatic hydrops by MR imaging has become possible and many research results have been reported regarding the imaging methods, evaluation methods, the correlation between imaging results and functional otological tests and the correlation between imaging findings and clinical symptoms. In this article we summarize the development of current imaging methods, evaluation techniques and clinical reports based on a review of the literature. We also attempt to characterize the current significance and future directions of MR imaging of endolymphatic hydrops.

Diluted Gadoteridol Causes Mild Ototoxicity in Cochlear Outer Hair Cells

Objectives: Recently, visualization of endolymphatic hydrops has been achieved through intratympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, the effects of gadoteridol (ProHance®) on inner ear cells are not yet understood. Here, we investigated the physiological and morphological responses of guinea pig cochlear cells to gadoteridol. Methods: Distortion product otoacoustic emission (DPOAE) levels were measured before and 1, 2, and 4 weeks after intratympanic injection of a 1/8 or 1/16 dilution of gadoteridol in guinea pigs. Moreover, morphological changes of isolated cochlear outer hair cells (OHCs) were observed after application of gadoteridol and GdCl3. Results: At the highest frequency (F2 = 12000 Hz), DPOAE level was significantly ( P &lt; 0.05) lower in the 1/8 diluted gadoteridol group than in the control group. Cell shape changes were observed in 24% (6/25) and 3% (1/33) OHCs after application of 1/8 and 1/16 diluted gadoteridol, respectively. The occurrence of morphological damage was significantly lower after application of saline compared to 1/8 diluted gadoteridol ( P &lt; 0.05). Moreover, morphological damage was significantly lower after application of 1/16 diluted gadoteridol compared to 1/8 diluted gadoteridol ( P &lt; 0.05). Morphological damages were shown at high rate (8/10 cells, 80%) after application of GdCl3. Conclusions: Administration of diluted solutions of gadoteridol might cause considerably less toxic effects on cochlear OHCs.

Imaging Evaluation of Endolymphatic Hydrops in Cases with Otosclerosis

Objectives: Human temporal studies have shown that endolymphatic hydrops (EH) is accompanied by otosclerosis, which is a risk factor for complications after stapes surgery. Recently, visualization of EH has become possible using magnetic resonance imaging (MRI) with contrast agents. The presence of EH in cases with otosclerosis was investigated by MRI to prevent complications following stapes surgery. Methods: Sixteen ears from nine cases diagnosed as having otosclerosis were evaluated by 3-Tesla MRI examinations taken 4 h after intravenous gadolinium injection. More than half of the ears showed mixed hearing loss and were suspected to have cochlear otosclerosis. Imaging data were compared with clinical findings in all ears and postoperative symptoms in ears undergoing surgery. Results: Varying degrees of EH were observed in 14 of the 16 ears. Episodes of acute sensorineural hearing loss or vertigo occurred in 4 ears with severe EH in the cochlea and 3 ears with severe EH in the vestibules. Overall, 12 of 14 ears with EH did not undergo stapes surgery. Ears without EH showed no postoperative complications, but one ear with mild EH in the vestibule showed severe vertigo following the surgery. Conclusions: The presence of EH in cases with otosclerosis was clearly visualized, and the degree of EH was correlated with the clinical findings in most patients. Such preoperative MRI evaluation could provide useful information to prevent complications following stapes surgery.

Visualization of endolymphatic hydrops in 3D-FLAIR MRI after intratympanic Gd-DTPA administration in Meniere's disease patients

To study the feasibility of endolymphatic visualization and the diagnosis of Meniere's disease by applying intratympanic gadolinium administration through the tympanic membrance and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI). To study the relationship between the endolymphatic hydrops visualized by MRI and audio-vestibular functional tests, such as pure tone audiometry (PTA), electrocochleography (EcoG), caloric test and vestibular evoked myogenic potential (VEMP). With a three Tesla magnetic resonance imaging (MRI) unit, 3D-FLAIR imaging was performed 24 hours after intratympanic gadolinium through the tympanic membrance in 32 patients with clinically diagnosed unilateral Meniere's Disease. We visualized the enhanced imaging of perilymphatic space in bilateral cochlea, vestibular and (or) canal, scoring scala tympani and scala vestibule of bilateral cochlear basal turn respectively and measuring the developing area of bilateral vestibule and the signal intensity ratio (SIR) between the vestibule and the brain stem subjectively. PTA, EcoG, caloric test and VEMP were performed. The relationship between the endolymphatic hydrops visualized by MRI and audio-vestibular functional tests were studied. The gadolinium appeared in almost all parts of the perilymph in cochlea, vestibular and (or) canals in all 32 patients' inner ears, so the endolymphatic space was clearly shown on 3D-FLAIR imaging. The scala vestibuli score value between the affected side and the healthy side were statistically significant (Z = 4.309, P < 0.05) . The developing vestibular area between the affected side and the healthy side [(6.04 ± 2.89) mm(2), (8.28 ± 3.04)mm(2)] were statistically significant (t = 3.322, P < 0.05) . Abnormal vestibular evoked myogenic potentials were significantly correlated with the developing vestibular area of the affected side (F = 11.96, P < 0.05) . Abnormal electrocochleography were significantly correlated with scala vestibuli score value of cochlear basal turn in the affected side (Z = 3.17, P < 0.05) . No significant correlation was found between the scala vestibuli score value or the developing vestibular area and caloric test or PTA findings. 3D-FLAIR MRI with intratympanic gadolinium injection through the tympanic membrance can discriminate the border between the perilymph and the endolymph and show endolymphatic hydrops. This method may provide radiographic reference for the diagnosis of Meniere's disease. The results of VEMP and electrocochleography might have appropriate correlation with degree of vestibular and cochlear hydrops.

Diluted gadoteridol (ProHance®) causes mild ototoxicity in cochlear outer hair cells

Conclusion: Administration of diluted solutions of gadoteridol might cause considerably less toxic effects on cochlear outer hair cells (OHCs). Objectives: Visualization of endolymphatic hydrops is done by intratympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. Here, we investigated the physiological and morphological responses of guinea pig cochlear cells to gadoteridol. Methods: Distortion product otoacoustic emission (DPOAE) levels were measured before and 1, 2, and 4 weeks after intratympanic injection of 1/8 or 1/16 dilution of gadoteridol in guinea pigs. Morphological changes in isolated cochlear OHCs were observed after application of gadoteridol and GdCl3. Results: At the highest frequency (F2 = 12 000 Hz), DPOAE level was significantly (p < 0.05) lower in the 1/8 diluted gadoteridol group than in the control group. Cell shape changes were observed in 24% (6/25) and 3% (1/33) of OHCs after application of 1/8 and 1/16 diluted gadoteridol, respectively. The occurrence of morphological damage was significantly lower after application of saline compared with 1/8 diluted gadoteridol. Morphological damage was significantly lower after application of 1/16 diluted gadoteridol compared with 1/8 diluted gadoteridol (p < 0.05). Morphological damage was observed at a high rate (8/10 cells, 80%) after application of GdCl3.

Visualization of Endolymphatic Hydrops in M^|^eacute;ni^|^egrave;re's Disease after Intravenous Administration of Single-dose Gadodiamide at 1.5T

Visualization of Endolymphatic Hydrops in M^|^eacute;ni^|^egrave;re's Disease after Intravenous Administration of Single-dose Gadodiamide at 1.5T

Visualization of endolymphatic hydrops and correlation with audio-vestibular functional testing in patients with definite Meniere's disease

Visulization of endolymphatic hydrops has been reported using magnetic resonance imaging (MRI) in patients with Meniere's disease. However, the relationship between the endolymphatic hydrops visualized by MRI and audio-vestibular functional tests have not been sufficiently investigated, such as pure tone audiometry (PTA), electrocochleography (EcoG), and vestibular evoked myogenic potential (VEMP). Here we attempted to visualize endolymphatic hydrops in patients with Meniere's disease using 3Tesla (3T)-MRI following intratympanic gadolinium-diethylene-triamnie petaaetic acidbis (Gd-DTPA) injection and correlated the presence of hydrops with auditory testing. Following intratympanic Gd-DTPA contrast injections in 26 patients diagnosed as having definite Meniere's disease, 3D-fluid-attenuated inversion recovery (3D-FLAIR) sequence imagings were performed. The PTA, EcoG, and VEMP testing was done bilaterally. Patients had typical results of auditory testing for Meniere's disease. The 3D-FLAIR MRI clearly demonstrated endolymphatic hydrops with signal voids in the cochlea (81%) and saccule (69%) in the definite Meniere's disease group. Auditory tests verified that the visualized cochlear hydrops (basal turn) was correlated with a high tone hearing threshold in PTA and an abnormal EcoG. Though the absence of VEMP did not correlate with vestibular hydrops on MRI, large vestibular hydrops were detected by imaging. This study demonstrates that endolymphatic hydrops could be visualized by 3D-FLAIR MRI in Meniere's disease patients. Cochlea hydrops and vestibular (saccular) hydrops are readily visualized using these techniques. Hydrops, as visualized on MRI, may be a reliable means to diagnosis Meniere's disease; this is supported by appropriate correlations with auditory vestibular functional testing.

Visualization of Endolymphatic Hydrops in Ménière's Disease after Single-dose Intravenous Gadolinium-based Contrast Medium: Timing of Optimal Enhancement

Visualization of endolymphatic hydrops (EH) in patients with Ménière's disease (MD) is now possible by heavily T(2)-weighted 3-dimensional fluid-attenuated inversion recovery (hT(2)W-3D-FLAIR) obtained 4 hours after intravenous (IV) administration of single dose gadolinium-based contrast medium (GBCM). Although maximum enhancement has been reported 4 hours after contrast administration in healthy volunteers, the timing of optimal enhancement in patients with MD is not reported. We investigated if that optimal timing is earlier or later than 4 hours. We evaluated 10 consecutive patients with suspected MD whom we randomly divided into 2 groups. We obtained hT(2)W-3D-FLAIR before GBCM administration and 10 min, 3.5 hours, and 4 hours after GBCM administration in Group A and before and 10 min, 4 hours, and 4.5 hours after GBCM administration in Group B. We compared signal intensity ratio (SIR) values of the perilymph and pons between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B and evaluated grades of EH at 3.5 and 4 hours in Group A and at 4 and 4.5 hours in Group B. SIR values did not differ significantly between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B. However, SIR values at 4 hours were significantly higher in Group A than Group B. Grades of EH agreed between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B. The optimal timing of contrast enhancement in patients with suspected MD remains unclear, but evaluation of EH may be possible from 3.5 to 4.5 hours after contrast administration.

Contrast enhancement of the inner ear in magnetic resonance images taken at 10 minutes or 4 hours after intravenous gadolinium injection

Conclusion. Contrast enhancement of the inner ear by three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI) taken 4 h after intravenous gadolinium (Gd) injection was better than when taken at 10 min. Using heavily T2-weighted 3D-FLAIR MRI, visualization of endolymphatic hydrops (EH) was possible in the vestibule and the cochlea after a standard intravenous dose of Gd. Objectives. To define a suitable time point for imaging Gd uptake in the inner ear acquired with heavily T2-weighted 3D-FLAIR MRI after standard intravenous Gd administration. Methods: Using a 3 Tesla MRI unit, heavily T2-weighted 3D-FLAIR MRI images were taken twice at approximately 10 min (conventional timing) and 4 h after intravenous gadodiamide (0.1 mmol/kg) injection in 10 patients with inner ear diseases including Ménière's disease. Results: The 4 h delay increased Gd enhancement of the 3D-FLAIR MRI images of the perilymphatic space in both symptomatic and asymptomatic ears. The increase in Gd enhancement was greater in symptomatic than in asymptomatic ears. Using this heavily T2-weighted 3D-FLAIR technique, EH was observed in both the cochlea and vestibule in images taken 4 h after the intravenous Gd injection.

A perspective from magnetic resonance imaging findings of the inner ear: Relationships among cerebrospinal, ocular and inner ear fluids

Visualization of endolymphatic hydrops has been performed using magnetic resonance imaging (MRI) after intratympanic or intravenous gadolinium (Gd) injection. Our recent findings indicate that just as the prevalence of asymptomatic glaucoma is greater than that of symptomatic glaucoma, there are also many cases of asymptomatic endolymphatic hydrops. It is assumed that the asymptomatic endolymphatic hydrops that precedes Ménière's disease is found more frequently using MRI than with other techniques. Gd in the inner ear moves into the cerebrospinal fluid (CSF) via the internal auditory meatus. Gd enhancement is also recognized in the ocular fluid after the intravenous Gd administration. In this paper, the relationships between CSF, ocular fluid and inner ear fluid are reviewed. The central nervous system, eye and inner ear contain specialized extracellular fluids that are essential for maintaining their function: CSF, ocular fluid consisting of vitreous humor and aqueous humor, and inner ear fluid consisting of perilymph and endolymph. Abnormal accumulation of or pressure elevation in these fluids is associated with hydrocephalus, glaucoma and Ménière's disease, respectively. The dura mater and the arachnoid membrane of the optic nerve canal and inner ear meatus are very close to the eye and the inner ear, respectively. It has been reported that low CSF pressure is associated with glaucoma and endolymphatic hydrops. In glaucoma and Ménière's disease, nerve damage to ganglion cells rather than damage of the sensory cells is directly associated with progression of the disease. Retinal ganglion cells in glaucoma and spiral ganglion cells in Ménière's disease are targets of the abnormal accumulation of, or increased pressure in, the extracellular fluid, just as neurons are damaged in hydrocephalus. Studies on hydrocephalus, glaucoma and Ménière's disease as a group may deepen our understanding of each disease.